biolong.weebly.combiolong.weebly.com/.../a_pii_lesson18_studentresource_123115.docx · Web viewThese fats are liquid at room temperature, and liquid in your body. Unsaturated fats

AOHS Foundations of Anatomy and Physiology II

Lesson 18 The Digestive System

Student Resources

Resource Description

Student Resource 18.1

Notes: Physiology of the Digestive System


Reading: Physiology of the Digestive System


Reading: Nutrients


Notes: Nutrient Metabolism


Reading: Nutrient Metabolism


Reading: Digestive System Conditions


Reading: Nutrition in the News


Guide: Digestive System Song


Glossary: The Digestive System (separate Word file)

Copyright © 2014‒2016 NAF. All rights reserved.

AOHS Foundations of Anatomy and Physiology IILesson 18 The Digestive System




Notes: Physiology of the Digestive SystemStudent Name:_______________________________________________________ Date:___________

Directions: Label the parts of the digestive system and fill in the chart as you watch the presentation on the physiology of the digestive system.

1. Describe the four steps in the digestive process.

a)

b)

c)

d)

2. Explain why materials that stay inside your GI tract can be considered to be outside of your body.



3. Complete the chart.

Step in digestive process

Organs involved(one per line)

What each organ does

Step 1: Ingestion

Step 2: Digestion

Step 3: Absorption

Step 4: Defecation



Step in digestive process

Organs involved(one per line)

What each organ does

4. Explain how peristalsis allows you to be able to swallow food while you’re upside down.

5. Explain why the very acidic digestive juices in your stomach don’t destroy the cells of your stomach lining.

6. Label the parts of the digestive system on the diagram below:



7. What are at least five functions of the liver?

8. Explain how your body fits a surface the size of a tennis court into your small intestine.

9. What causes flatulence?




Reading: Physiology of the Digestive System





Look at the skin on your hand. Remember, all those cells you can see were made a week ago and have moved to the surface. A lot of what they’re made of came from food that you ate around that time. The digestive system breaks down your food into smaller molecules, and it uses those smaller pieces to build new molecules in forms that your body can use.

The main role of your digestive system is to extract nutrients from the food you eat so they can be distributed to the body’s cells and used for energy and growth. That’s one reason why what you eat can really make a difference to how well your body functions.



The digestive system is a complex and elegant food processor. Don’t let its name fool you—it does a lot more than just digest food. For starters, you have to ingest the food, or get the food into your body, which you do using your mouth and esophagus. Then food needs to be digested, or broken down into molecules like amino acids, simple sugars, and vitamins that your body can use or store. Digestion happens mostly in the stomach and small intestine. After that, those usable molecules need to get into your bloodstream, or be absorbed, which happens in the small intestine. And finally, once your body has gotten all it can from your food, it needs to get rid of what it can’t use, along with other body wastes and a whole lot of bacteria, which happens in your large intestine.



Most of the organs in your digestive system are part of your gastrointestinal, or GI tract (which is also sometimes referred to as the alimentary canal). The inner region of your GI tract (i.e., within the alimentary canal) is technically considered to be the outside of your body. It’s one long tube that is open to the environment on each end. The substances that stay in your GI tract go in at one end and come out the other, without ever entering the body’s tissues.

Along the length of the GI tract, each segment plays a role in extracting nutrients from the food you’ve eaten, or helping you get rid of substances you don’t absorb. Two organs, the liver and the pancreas, provide important substances that contribute to our digestion. These two organs also contribute to many other body functions. Therefore, they’re considered accessory organs to the digestive system.



As soon as you take a bite of something, such as an apple, you’re setting the whole process of digestion in motion. You ingest food with your mouth, where your teeth chomp it into smaller bits that you can swallow, and your tongue mixes it with saliva. Even before you’ve taken that bite, your salivary glands have begun to release saliva. Saliva contains some important digestive enzymes, and as soon as you begin to eat, your saliva starts breaking down starches.



Once you’ve chewed a bite of food, the mass that’s ready to be swallowed is called a bolus. When you swallow the bolus, it goes through your pharynx to your esophagus on its way to your stomach. Remember, the pharynx also leads to your lungs. When you swallow, the epiglottis closes over your larynx so that food, water, or even saliva doesn’t go into your lungs. Occasionally, if you eat or drink too fast or are distracted, what’s going down your throat will move faster than your epiglottis, and you’ll get something “down the wrong pipe.” Thankfully, this doesn’t happen very often.

Your esophagus is a muscular tube about 10 inches long that goes through the diaphragm and ends at the stomach. Its main purpose is to propel what you swallow toward your stomach using rhythmic muscular contractions called peristalsis.



The esophagus is just one of several organs in the digestive system that use peristalsis to keep your food and food waste moving through you. Peristalsis is a coordinated wave of muscle contraction and relaxation that moves in one direction. It only occurs in involuntary muscles, usually in muscles that form a tube. When peristalsis is happening, a ring of muscle will contract above the bolus of food (assuming you are upright), pushing the food toward the stomach. The muscle in front of the bolus remains relaxed, allowing the contraction to push the bolus through. The muscle contraction will move through the muscle in that same direction, pushing the bolus along ahead of it. Peristalsis also happens in the stomach, gallbladder, small and large intestines, rectum, and some organs of the urinary system.



While most of the organs in the GI tract have a special arrangement of muscles that produce peristalsis, the stomach has an additional layer that allows it to really mash food around and may even break it into smaller pieces. When your stomach starts to fill up, stretch receptors in the stomach walls send the message that it’s time to start the action. Your stomach doesn’t have to be full, though, for this mashing and churning to begin. Sometimes just the sight or smell of something delicious can get your stomach going. And if you’re hungry, your stomach might start up on its own, sending the message that it’s waiting for some food to arrive.



Cells in the stomach produce two different substances that work together to begin the chemical process of digestion. Some stomach cells produce enzymes that start breaking down proteins. Enzymes are special proteins that make chemical reactions in the body happen faster. But these enzymes require an acidic environment in which to work, which is why the stomach contains hydrochloric acid. The stomach also makes a protective kind of mucus that lines the stomach and keeps the acid from digesting your stomach cells.

Broken-down food mixed with digestive enzymes becomes a creamy paste called chyme. It takes the stomach between two and six hours to create chyme.

No nutrients are actually absorbed in the stomach. Two substances, aspirin and alcohol, pass right through the stomach into the bloodstream. That’s why it’s important for a person to have food in their stomach when he or she is drinking alcohol; the food will slow down the absorption of alcohol into the blood.



The small intestine is the longest organ in the body. If you could stretch it out, it would be at least three times as long as you are tall. All of this muscle is wound up in a precise way and takes up a big chunk of the space in your abdomen. As digestion takes place, small amounts of chyme are pushed slowly along the length of the small intestine. When you have a “stomach ache,” it’s often in your intestines, caused by gas that’s trapped and needs to make it around one of the corners of the folds. The gas is produced by the millions of bacteria that live in your small intestine (and in your large intestine, too). They eat some of what’s in your food and even help you digest it. A byproduct of their digestion is gas, often odorless methane or nitrogen.

The small intestine is always slightly contracted and usually busy doing something. In a living adult, it can be anywhere between 10 and 30 feet long. Once a person dies, his or her small intestine no longer stays contracted, and it can be 5 to 10 feet longer.



The liver produces a yellowish green substance called bile, which contains bile salts. Bile salts break down large globules made of many fat molecules stuck together into smaller pieces. Once the liver has made bile, it sends the bile to the gallbladder, where it’s stored until it is needed. When the gallbladder gets the signal, it uses peristalsis to empty bile into the duodenum through a small duct. Because the gallbladder does not make bile, its removal generally has limited impact on digestion. The person still makes bile—it just gets delivered directly to the small intestine. Bile has a foul taste and the word bilious describes a person who has a foul or unpleasant disposition.



The liver is the second largest organ in the body (the skin being the largest), and is something of a jack-of-all-trades. Its digestive function is only one of many vital things it does for the body. The liver is also a filter; it removes toxins left behind by drugs or substances such as alcohol and recycles the iron from old red blood cells. It stores glucose that the body calls on when blood sugar is low, and it is also a parking place for many vitamins and minerals. The liver secretes proteins that circulate in the blood plasma, such as complement and clotting proteins, as well as multiple hormones.

The liver is also the only internal organ capable of regenerating if a large portion of it has been damaged (the skin easily regenerates if its wounds are small but can’t if they are too large). A person can regenerate an entire liver if he or she has up to 25% of a healthy liver left. That means a living person can donate part of his or her liver to another person for a transplant. On average, the donor’s liver will have regenerated within six weeks.



You already know that the pancreas plays an important role in the body’s ability to bring sugar into cells. The pancreas is also very important in the digestion of our food. The organ, tucked into a curve of the duodenum and beneath the stomach, produces a fluid called pancreatic juice, which contains a variety of enzymes. Individual enzymes digest specific types of molecules. Together, this group of enzymes is able to do some digestion on every category of food molecule.

When the pancreatic juice leaves the pancreas, it flows into a duct that meets up with the duct from the gallbladder. The two ducts fuse to become one duct that empties the fluids from both organs into the duodenum.



When we eat, our bodies take in lots of fats and proteins that were helpful to the plant or animal they came from but that the human body can’t use. We also take in nucleic acids. These are made of molecules of DNA and RNA. RNA is very similar to DNA. These big molecules need to be remade to be useful to us. The proteins in a peanut, for example, are meant to help a peanut plant grow. But they’re made of the same amino acids that our important proteins are made of, like the ones in our cell membranes or the antigens on our blood cells. So your body breaks down the peanut proteins into amino acids and uses those amino acid molecules to make the proteins you need. For the same reason, your body breaks down carbohydrates into simple sugars like glucose, DNA and RNA into their nucleic acids, and fats into their basic components of fatty acids and glycerol. The body then reuses the building-block molecules to make proteins, fats, DNA, and RNA that we need.



The small intestine is where the digestion and absorption action really takes place, and it’s where nutrients enter your bloodstream. The inner epithelial layer of the small intestine has thousands of tiny projections in it, called villi. These villi greatly increase the surface area of the small intestine. In addition, the cells that make up these villi have microscopic, finger-like projections on them, called microvilli. These projections increase the surface area even further. All told, if you could flatten all these folds and projections, your small intestine could cover a tennis court!

Inside the folds of the villi are dense capillary beds. Nutrients move into the cells of the villi and from there into the bloodstream through the capillaries.



As chyme makes its way through the small intestine, most of its nutrients are absorbed. When it reaches the end, peristalsis pushes the material that’s left into the large intestine, also called the colon. Once material enters the large intestine, it’s called feces. The large intestine is much wider and shorter than the small intestine. It makes a sort of ring around the outside of the small intestine. The main role of the large intestine is to absorb water that’s left in the feces and pass it into the rectum, along with undigested food, unabsorbed bile, and bacteria.

The appendix is a worm-shaped extension hanging off an area near the start of the large intestine. For many years, doctors have presumed that the appendix has no function. But now that researchers are becoming more aware of the number and role of bacteria in the intestines, some are looking into whether the appendix has a hand in maintaining or stabilizing the bacterial populations in the gut.



The walls of the colon produce lots of mucus that allows the feces to exit smoothly. There is more to feces than just the remainders of the food you’ve eaten. Another large component of feces is bacteria. There are many bacteria living in both the small and large intestines. Bacteria in the large intestine produce some important products. For example, some produce vitamin K, which is important in blood clotting. Some of the bacteria in the large intestine make their meals from parts of food that we don’t digest, such as fiber. Often, these bacteria give off sulfur dioxide as a product. It escapes from the colon, along with gasses produced by bacteria in the small intestine, as flatulence.



Several times a day, the colon goes through long, slow peristaltic contractions that push the feces from the intestine into the rectum. Fiber, which is the indigestible parts of plant foods that we eat, can make these contractions stronger and can soften feces, making it easier to move along. Therefore, it’s a good idea to make sure you get enough fiber in your diet. As the feces reaches the end of the rectum and the beginning of the anus, it sets off a reflex. This reflex sends a signal to the brain that there is feces ready to make an exit. The brain then makes a decision about whether the moment is right or not. If the decision is to hold off, the rectum will stop sending the signal for a bit. If the colon goes through peristaltic contractions again, that will set off the defecation reflex once more.



The anus has two sphincters, or rings of muscle, that contract or expand to be closed or open. The inner sphincter is made of involuntary muscle. The defecation reflex signal from the rectum causes this sphincter to relax. The outer sphincter is made of voluntary muscle. Under ordinary circumstances, the brain makes the decision whether to open this sphincter. When it does, peristalsis in the muscles of the rectum push the feces through the anus and out of the body.



When babies are born, their digestive systems, like many other systems, aren’t fully developed yet. Of course, babies don’t have any teeth, so they can’t chew solid food. But they don’t need any teeth yet, because they can’t digest solid food either. It takes their intestines and other internal organs about six months of development before they begin to produce enzymes.

Our digestive system is changing all the time, in response to many factors. What we eat, how much exercise we get, how stressed or tired we are can all affect our digestive system. As people grow older, they sometimes lose muscle tone in their digestive organs. That means food moves more slowly through them. Older people sometimes eat less because their stomachs may stay full longer. And feces may stay in the large intestine longer, causing constipation. The body removes more water from the feces, which can make more difficult to move it out of the large intestine.



It’s been known for some time that there are lots of bacteria in your gut. But only recently has research started to reveal that these microbes may play a significant role in the health of your digestive system and in other systems as well.

Researchers are learning more each day about how the microbes in your intestines affect what you digest and absorb. Many new studies are leading to the idea that we can affect the collection of microbes that are in our guts by the foods we eat. Having more species seems to have a positive effect on health and weight—yet another health benefit to eating a wide variety of foods.

Some foods and dietary supplements containing probiotics are starting to appear on market shelves. Some of these, like yogurt, have been around for centuries. Others are newer. Scientists are just at the beginning of understanding the bacteria in our digestive systems, and so there is still a lot to learn about how—or whether—probiotics make a difference in overall health.




Reading: NutrientsStudent Name:_______________________________________________________ Date:___________

Directions: Carefully go through the reading below and answer the questions.

Imagine that you’re busy studying for finals, and you also have to work every night at your job busing tables at a restaurant. You’re going to need to be as energized and efficient as possible to do both jobs well. If you think coffee is the best way to get yourself through times like this, think again. Making sure you get all the nutrients you need is a much better approach. Nutrients keep your memory and attention as perky as they can be, and power your brain and body through all you have to do. Without the nutrients you need, no amount of caffeine will save the day.

Nutrients are molecules your body needs to carry out its essential functions but that it can’t make on its own. Therefore, you have to get your nutrients by eating them. Some people also take nutritional supplements, pills or powders that contain a large amount of a specific nutrient. These may be helpful, but the way our bodies absorb and use nutrients is complex, and many studies show that our bodies incorporate nutrients best when we get them by eating whole foods like grains, fruits, and vegetables.

There are two types of nutrients:

Macronutrients are molecules that provide us with energy. They make up the calories in our diet. These nutrients are called macro, which means “large,” because we need large amounts of them.

Micronutrients are called micro because they are molecules we need in very small amounts. Even though we don’t need to take in tons of these nutrients, they are essential to our being able to produce hormones, enzymes, and other substances we need to keep our bodies going.

MacronutrientsMacronutrients are divided into three categories. Each group is different chemically and is used and broken down in the body differently.

Carbohydrates

Your body needs more carbohydrates (carbs) than it needs of any other nutrient. Carbs are the main source of energy for everything your body does. All your tissues can use carbohydrates for energy, and carbs are the only molecule our brains can use.

Carbohydrates take many forms, but chemically, they’re all made of sugar molecules. A spoonful of sugar is all carbs, and so is a plate of pasta and the inside of a baked potato. The pasta and potato are starches, which are made of long chains of sugar molecules. As you’ve seen, taking in a lot of sugar all at once can create a spike in blood sugar that stresses the pancreas. The same thing happens when you take in high-carbohydrate foods that don’t contain much fiber or other nutrients.



The way to avoid the sugar spike and still get the carbs you need is to eat foods that have other nutrients in them as well. Milk products, for example, like cheese and yogurt, have protein and fat as well as carbs. Those other nutrients share the space with the carbs in the small intestine, which means that your body doesn’t absorb so much sugar into the blood all at once.

Fresh fruits and vegetables contain another important kind of carbohydrate, called fiber, which is made of plant material called cellulose. Fiber also helps prevent sugar spikes, because it’s a type of carbohydrate that the body doesn’t digest. Although fiber doesn’t provide any energy, it’s important for moving waste through the large intestine, and a high-fiber diet can decrease the risk for heart disease, obesity, and colon cancer. You’ll find many high-fiber foods on the lists of foods that are good for preventing diabetes.

One gram of carbohydrate has 4 calories. That means for every 100 grams of carbs you eat (about 3 ounces), you take in 400 calories. The US Department of Agriculture, which publishes nutritional guidelines, suggests that about 40% of our calories should come from carbohydrates.

1. Why would high-fiber foods be good for people with or at risk of diabetes?

2. Explain why the carbs in orange juice produce a sugar spike but carbs in an orange don’t.

Fats

Fats have gained a reputation for being the enemy of health, but your body needs fat to function healthily and not all fats are created equal. While it’s true that fats pack a bigger caloric wallop—1 gram of fat yields 9 calories—when it comes to fat, the question is more about quality than quantity.

Fat is a necessary component of our diet, and everyone should get from 15%‒30% of his or her calories from fat. The word fat is mainly used to describe triglycerides, which are the storage form of energy found in animals and plants. But it might also be used to describe other lipids (molecules that are not soluble in water), such as cholesterol and phospholipids that have critical, nonenergy roles in the body.

Lipids not only provide you with a dense form of energy (lots of calories per gram) but they’re also responsible for helping your body absorb vitamins A, D, E, and K, as well as helping transport these vitamins around your body. These vitamins aren’t soluble in water, but they will dissolve in fat, which is necessary for your body to make use of them.

Phospholipids are necessary components of cell membranes. Cholesterol is another lipid found in cell membranes and is also the basis of many hormones. Unfortunately, many of us have too much cholesterol in our diet, increasing our risk of heart attacks and other conditions. You also need fats for your cell membranes. Note that fats are also called “lipids,” and your cell membranes contain a phospholipid bilayer. Cholesterol is one important lipid your body uses to make cell membranes and many types of hormones.

The best kinds of fats to eat are naturally produced unsaturated fats. This means the carbon chains in



the fat molecules aren’t saturated with hydrogen atoms. These fats are liquid at room temperature, and liquid in your body. Unsaturated fats can reduce a person’s blood cholesterol and help keep his or her blood sugar under control. Seed oils, nuts, olive oil, olives, fish, and fatty vegetables like avocados are

good sources of unsaturated fats.

Another kind of fat is saturated. Its carbon chains are saturated with hydrogen atoms—there aren’t any double bonds, as with the unsaturated fat. Saturated fat is solid at room temperature and occurs naturally in meats and dairy products, such as butter. Saturated fats can raise your cholesterol levels because the body packages these fats together with cholesterol into a molecule called low-density lipoprotein, or LDL. (You will learn about the other kind of cholesterol you may have heard of, HDL, later in this lesson.) In blood vessels with atherosclerosis, LDL contributes to plaque formation by unloading cholesterol into the wall of the blood vessel. Many doctors encourage patients, especially those with high blood pressure, to keep their LDL levels low to try to avoid plague buildup.

If you look at the nutrition facts label on packaged food, you’ll see a number for dietary fat, and then you’ll often see two other specific types of fat listed: saturated fat and trans fat. These two types of fat are singled out because they have problems associated with them other than the potential for weight gain. Both of these fats can raise your cholesterol levels because they tend to increase your LDL.

You might also have heard of trans fats. Trans fats are unsaturated fats that have been hydrogenated. This means that hydrogen atoms have been added to the carbon backbone that makes up the fat. A good example of trans fats is vegetable shortening. To make vegetable shortening, hydrogen atoms are added to naturally occurring vegetable oils, making the fat solid at room temperature. Trans fats don’t exist naturally, and they aren’t considered healthy. They’re used mostly in packaged baked goods like cakes and cookies to preserve them and keep them from spoiling. Trans fats are often listed as “hydrogenated” or “partially hydrogenated” oil in a list of ingredients. Trans fats can raise LDL levels in the same way that saturated fats can. Although it’s hard to completely avoid saturated fats, since they occur naturally in meat and dairy products, it’s not hard to keep trans fats out of your diet.



3. Why could high cholesterol levels be considered a health risk?

4. What foods do you eat that contain trans fat?

Proteins

If you’ve cruised the energy bar aisle in the store, you’ve probably noticed that many of the energy bars advertise that they’re “high in protein.” Athletes praise protein as a means of building stronger muscles, but protein’s glories go far beyond that. Many of the enzymes and hormones that make chemical reactions happen in your body are made of protein. Hemoglobin is an example of one of the many proteins in your cell membranes that carry vital substances from one place to another in your body. Antigen proteins are the mechanism used by the immune system. And, when other sources of energy are used up, your body can turn to protein for that, too.

Proteins are long chains of molecules called amino acids. There are 21 different kinds of amino acids. Your body can make 12 of them, but 9 of them are essential, which means you have to get them from something you eat. When you eat a protein, your body breaks the long chain down into its amino acids and then uses those as building blocks to make new proteins.

If a source of protein contains all of the essential amino acids (the nine that your body can’t make), it’s considered a complete protein source. Most meats and dairy products are complete sources of protein. There are other foods that have a lot of some essential amino acids but not so many of others. These are called incomplete proteins. A good way to get all the protein you need without eating meat is to eat complementary protein sources. An example would be rice and beans: rice (especially brown rice) has a lot of some essential amino acids but not others. Beans, however, are high in the amino acids that rice lacks. Together, the two provide a complete set of essential building blocks.

Nutritionists suggest that you get from 15%‒30% of your calories from protein. Most people get all the protein they need, and, even for athletes, protein supplements aren’t necessary. In fact, most Americans eat more protein than their body requires. That’s not a problem, though many much-loved sources of protein—hamburger, cheddar cheese, ice cream—are also high in saturated fats. Choosing lean cuts of meat and low-fat milk, cheese, and yogurt can help cut the fat and, therefore, the calories.

Like carbohydrates, proteins provide 4 calories per gram. But your body uses protein for energy only as a last resort. Since protein has so many other uses, you body prefers to make other proteins out of it and uses mostly carbs and fats to generate energy instead.



5. Why do you think having enough protein is especially important for growing babies and children?

6. Why would you expect meat to be high in protein?

Water

Yes, plain old water is considered a nutrient and is absolutely vital to your remaining alive. Your body is about 65% water by weight, but it can’t make water on its own. You can survive for weeks without any of the other nutrients, but you’ll only make it a few days without water. That necessity makes water the most essential of nutrients.

Your body uses water in nearly all of its functions. Almost every cell in your body is bathed in a fluid that is mostly water. The mucus that lines your respiratory and digestive tracts is mostly water. Fluid surrounding your brain and spine cushion and protect them. Your body uses water to control blood pressure and body temperature. Your blood plasma is mostly water, and it’s that solution that carries out much of the vital transport of body products, wastes, and toxins.

You’re losing water all the time. Some of it escapes simply by the fact that you’re breathing it out. In fact, the average person loses about a liter of water a day just from breathing, and another liter and a half from urinating. When you exercise or when it’s hot out, you sweat out additional water. When you lose too much water—a condition called dehydration—you get a headache and feel fatigued or nauseous. Eventually, if you’re severely dehydrated, you may find it hard to swallow and to control your muscles.

It’s important that you replace the water you lose each day. You get about 20% of your water from the food you eat. The other 80% you need to drink. The Institute of Medicine recommends that teenagers drink about 2.5 liters of water a day. So, imagine a 2-liter soda bottle; you want to drink about 1¼ of those a day. But—and this is important—you should drink 2.5 liters of water and not 2.5 liters of soda. Soda often has caffeine and sodium, both of which can throw off your water balance. Juice and milk are also good sources of water, but both contain quite a few calories.

7. Why can your body survive so much longer without food than without water?



MicronutrientsVitamins and minerals are the two forms of micronutrients your body needs.

Vitamins

There’s more to the vitamin alphabet than the letter C: in fact, there are 13 different vitamins you need to stay healthy. Each vitamin carries out its own duties, and no vitamin can substitute for any other.

Vitamins are small, organic molecules that play a part in making many of your body’s necessary chemical reactions happen. This table gives you a brief idea of what each vitamin does for you. Most of them play many roles, and some of the B vitamins take part in over 100 chemical reactions.

The 13 Vitamins

Vitamin Role Good sources Soluble in:

A Keeps bones and skin healthy, helps produce white blood cells, antioxidant

Cheese, eggs, sweet potato, carrots, squash

Fat

Thiamine (vitamin B1)

Extracts energy from carbohydrates

Found in most foods Water

Riboflavin (vitamin B2)

Makes new red blood cells, body growth, important in metabolism

Milk products, leafy greens, whole grains

Water

Niacin (vitamin B3)

Maintains healthy skin and nerves, important in metabolism

Meat, poultry, fish, mushrooms, asparagus

Water

Vitamin B6 Forms red blood cells, production of serotonin, aids brain function

Found in most foods Water

Vitamin B12 Helps break down fats and proteins, keeps neurons healthy

Meat, poultry, eggs, milk products Water



The 13 Vitamins

Vitamin Role Good sources Soluble in:

Biotin Helps form glucose from other sugars and break down some fats, keeps hair and skin healthy

Found in many foods Water

Pantothenic acid

Important for metabolism, and helps produce hormones and cholesterol

Found in many foods Water

Folate (folic acid)

Assists in making new DNA and important in creating new cells

Leafy greens, legumes Water

C Antioxidant, helps your body absorb iron, supports your immune system

Citrus fruits, peppers, tomatoes, vegetables in the cabbage family

Water

D Helps your body absorb calcium

Eggs, fish, fortified milk. Made by the body when exposed to sunshine.

Fat

E Antioxidant, helps the body produce red blood cells

Leafy greens, plant oils, whole grains, eggs, nuts, seeds

Fat

K Plays a role in blood clotting Leafy green vegetables. Bacteria in the intestine can also produce it.

Fat

We categorize vitamins into two groups: fat soluble and water soluble, based on their chemical properties. Fat-soluble vitamins dissolve in fat, and your body is able to store them in fatty tissues. Water-soluble vitamins dissolve in your body fluids; you lose some each day and must replace them through the food you eat. Most healthy people who eat a balanced diet get all the vitamins they need. Although it may seem healthy to take extra vitamins to be sure you’ve got your bases covered, it’s not necessarily harmless. Excesses of many vitamins can have side effects. You should be especially careful if you take supplements of fat-soluble vitamins; because your body hangs on to these vitamins, it’s easy to overdose on them. But even too much of many water-soluble vitamins can cause problems. Many recent studies have also questioned whether vitamin supplements are as effective as once believed. The best approach is to make sure to eat a variety of healthy foods, including fruits, vegetables, nuts, and small amounts of meat or dairy every day.

8. Why do you need to replace water-soluble vitamins each day?



Minerals

Minerals are inorganic substances, often ions of a particular element, that are as vital as vitamins are to your body’s functions. In some cases, vitamins and minerals work together to make important reactions happen in your body, but in many cases, minerals play a role just on their own. Sodium and potassium are examples of minerals that have a function on their own. As you know, your cells maintain certain concentrations of sodium and potassium inside and outside of the cell, and these concentrations provide the right conditions for chemical reactions. Calcium lends strength to your bones. Your body needs these minerals in greater quantities than it needs a group of minerals called trace elements. Trace elements are required in tiny quantities, but their roles are absolutely necessary, and you can’t live without them. Iron, for example, is a trace element, and without it, your blood wouldn’t have a way to carry oxygen. Other trace elements are fluoride, copper, selenium, iodine, and zinc.

In most cases, minerals are absorbed by the body better if they’re consumed in your food rather than as supplements. As with vitamins, having too much of a certain mineral can be problematic. High levels of sodium have been associated with high blood pressure and heart disease. For the most part, though, the greater concern is about not having enough minerals. Sodium is easy to get; there are large quantities of it in almost all processed foods. Trace elements and minerals like calcium and magnesium are less plentiful in packaged foods. Many people take supplements of these minerals, hoping that they will help maintain bone density and other aspects of health. But a more reliable way of getting the minerals you need is to eat a variety of fresh foods and dairy products.

9. How are vitamins and minerals different?

10. Are there any vitamins or minerals that you think you might not get enough of?




Notes: Nutrient MetabolismStudent Name:_______________________________________________________ Date:___________

Directions: Answer the questions and fill in the chart as you watch the presentation on nutrient metabolism.

1. What are the two types of metabolic reactions, and how are they different?

2. Explain:

Why is breaking down a starch into sugars a catabolic reaction?

Why is putting together amino acids to build more actin and myosin for muscle cells an anabolic reaction?

3. Fill in the chart.

Nutrient What it’s ultimately broken down into Roles it plays



4. Why is cholesterol important?

5. What different roles do LDL and HDL play?

6. What happens if there’s more sugar in your bloodstream than you can use at that time?

7. Why don’t you burn fat right away when you start exercising?

8. What are at least five things the body uses proteins for?

9. Why do we need fewer calories as we age?




Reading: Nutrient Metabolism





Once you’ve got those macronutrients inside you, your body takes them through a series of chemical reactions. Every second of your life, your body is breaking down glucose to get energy, building new cells, constructing proteins and enzymes, and doing hundreds of other chemical tasks. These reactions are called metabolic reactions because, collectively, they make up your metabolism. You can think of your metabolism as all the chemical reactions your body needs to keep itself in a state of being alive at a given moment. Your body performs many, many different kinds of metabolic reactions, and different substances go through different sets of reactions, creating many different products, such as new cells, hormones, and energy to fuel your muscles. There are two main groups of metabolic reactions. Catabolic reactions break down molecules you’ve taken into your body. Anabolic reactions build new substances from the products of catabolic reactions. The new products created by anabolic reactions are all derived from what you’ve put into your body. So, you truly are what you eat!



The two types of metabolic reactions produce different kinds of products. Catabolic reactions break down larger molecules into smaller ones. Fats, carbohydrates, and proteins all go through catabolic reactions, each being broken down into smaller parts that can be used to build new products. Or these smaller parts can go through more catabolic reactions to release energy to fuel processes in the body.

In contrast, anabolic reactions make larger molecules from smaller ones and use energy to do so. Most of the reactions that restock substances in your body that are depleted or in need of repair require the input of energy. And your body is constantly in need of restocking and of making new things, which is why it needs food every day. Using energy, anabolic reactions create the molecules that become parts of cells, hormones, new proteins, and many other materials. Anabolic reactions can also build molecules such as fats that store energy.



As you probably remember, the main molecules your body uses for energy and to build substances and structures it needs are carbohydrates, fats, and proteins. Each of these molecules has a different purpose in the body.

Carbohydrates are your body’s main source of energy that you can use quickly. Whether you eat candy, bread, beans, or rice, your body uses the carbohydrates for energy.

Fats can also provide energy if there aren’t enough carbs, but more often fats are just stored as fat tissue and used to make other important products that your body needs. Fat tissue can protect your internal organs, and components of fats are necessary for making structures in cell membranes. Cholesterol, a fat-like molecule, is also the basis for several hormones that are produced by cells in one part of the body and that travel to another part of the body.

Proteins provide the building blocks for new proteins and enzymes that make many of your cellular functions possible. They are also important parts of cell membranes and of tissues such as ligaments and tendons.



All of the cells in your body use glucose as a fuel source. Glucose is taken into cells and then goes through a series of catabolic reactions, usually using oxygen, to release energy. Along with energy, these reactions produce carbon dioxide and water.

Remember that the reason you need to breathe out is to get rid of carbon dioxide created as a waste product of cell functions. This is where that carbon dioxide comes from; it’s a product given off when your cells catabolize glucose.

Once glucose has been broken down, the carbon dioxide moves into your blood vessels as part of cellular respiration and circulates to your lungs, where you breathe it out. Meanwhile, the energy released by breaking down the glucose is used to power many cell processes and functions, like moving some molecules across membranes, building new molecules, and contracting muscles.



Your body has several clever survival mechanisms. One is to make sure that when you get a good meal, your body can store what it isn’t able to use right away so it will have energy for later, in case another good meal doesn’t come along when you’re hungry. First, your body makes glucose from the carbs you eat, and that glucose fuels your cells’ functions. If you eat more glucose than your body needs, it links many singular glucose molecules together in large, branched polymers called glycogen. You store glycogen in your liver and skeletal muscles. When the glucose levels in your blood run low, your liver will remove the glucose molecules from the glycogen and release them back into the bloodstream. Your body can generally store about a half day’s worth of glucose as glycogen.



If your glycogen stores are already generous and your blood sugar is high, your body will turn some of the circulating glucose into fat. Fat is another way for the body to store excess food that it doesn’t need right now so that it can be called upon in the future. This was very useful when humans were surviving off the land and hunting, without grocery stores and drive-through windows. These days, though, our food supply is much more reliable and we don’t need to rely on fat stored by our body to get us through the times between harvests and hunts. As a result, storing fat often leads to being overweight, which in turn leads to a whole host of health problems. Men tend to collect fat cells in the belly; in women, the fat cells tend to be more evenly distributed.

The signals your body looks for to turn glucose into fat are one reason why blood sugar spikes can lead to weight gain. When you eat foods that are mostly carbohydrates, such as white bread, white rice, candy, and soda, the resulting blood sugar spike encourages your body to make fat from the glucose. If the food you take in has other nutrients in it that will keep your blood sugar more steady, your body will use more of the glucose to keep you running and make less of it into fat.



Unlike glucose, which goes from the intestine to the cells to be metabolized, fats begin their metabolic reactions in the small intestine. They’re broken down into fatty acids and glycerol. Fatty acids are shipped off to the liver where they are packaged into larger molecules that transport them to the other tissues of the body. Many of these fatty acids will reform as fats in fat tissue. But some of the fatty acids will also be used to make the phospholipids found in our cell membranes.

If you’re exerting yourself and you don’t have enough carbs circulating in your blood, your body will tap into the fat stored around your body and start breaking it down to release energy. This is the role of fat that most of us strive to make more use of. Just like glucose, fat is catabolized into carbon dioxide, water, and energy. But if there’s no glucose coming in (if, say, a person hasn’t been eating any carbs) or if a person has diabetes and can’t use glucose for energy, the body may overmetabolize fats (and proteins), producing a byproduct called ketoacids. One of these acids can convert to acetone—the stuff that takes nail polish off your fingernails—which gives the breath a fruity smell.



Fat (triglycerides) is the main lipid that we take in as part of our diet. But we can also ingest other lipids (lipids are molecules that don’t dissolve in water), a main one being cholesterol. While cholesterol in your arteries is a bad thing, cholesterol in cell membranes is a very good thing. Cholesterol is a special kind of fat molecule that has some important roles in the body. It’s embedded in cell membranes and helps give them structure. It also works to block small, water-soluble molecules from getting through the cell membrane, so it’s important for maintaining what’s inside and outside of the cell.

Cholesterol is also the basis of all the hormones your body makes that are called steroid hormones. Their name comes from the fact that, chemically, cholesterol belongs to a group of molecules called sterols. Your sex hormones (androgens in men and estrogens in women) are steroid hormones, as well as other hormones stored in your adrenal glands. Your body also uses cholesterol to make vitamin D and some of the substances in bile that help you digest fats in your intestine.

Many people equate “steroids” with the anabolic steroids sometimes abused by certain athletes. Not all steroids produce muscle-building effects, but the ones that mimic testosterone can. Unfortunately, their abuse is associated with a number of serious side effects, such as heart attack, strokes, mood changes, and acne.



Because cholesterol, fats, and fatty acids are lipids, they don’t dissolve in our watery blood. After they’re absorbed from our digestive tract, these molecules are shipped to the liver, which packages them into larger molecules called lipoproteins. This mixes them with other molecules in a way that they can now travel through the bloodstream.

There are two main lipoproteins in the body. One is called LDL, or low-density lipoprotein, which is sometimes referred to as “bad cholesterol.” LDL contains about 50% cholesterol and is used to transport cholesterol to the tissue of our body. Because it is common to have so much cholesterol in our diet, a high number of LDL molecules can be made, and they will deposit some of the cholesterol in the walls of the blood vessels, which can lead to a heart attack or stroke. The other common type of cholesterol is HDL, or high-density lipoprotein. It’s made up of 20% cholesterol and its job is to soak up excess LDL in your blood and cart it off to the liver, which extracts the cholesterol and uses it to make bile or recycles it in other ways. HDL is sometimes called “good cholesterol” because having a higher level of it seems to protect people from heart disease.

Researchers are still trying to get a full picture of how your body maintains its cholesterol levels. They know the levels are affected by three things: how much your body makes, how well your body gets rid of it, and what you eat. Some people have genes that make them produce excess cholesterol. The amount of cholesterol in your body seems to be related more to the mix of fats and carbs you take in than to the actual amount of cholesterol you eat.



In your small intestine, proteins are broken down into their building blocks, called amino acids. There are 21 different amino acids used in humans to make proteins. The body can manufacture many of them, but a few of them are essential, which, remember, means that they have to be obtained from food. The amino acids enter your blood and first pass through the liver, which takes the amino acids it needs. The rest circulate in the blood, where they’re taken into cells.

Proteins play important roles that fats and carbs can’t play, so the body avoids breaking them down for energy unless it has run out of other sources. Proteins are the basis of so many important cellular products and are so important in making chemical reactions happen that cells are rather protective of their amino acid resources. As blood flows by cells, they may appear to hoard amino acids, grabbing whatever comes along. But, in fact, they’re filling out their collections. A cell can’t begin producing the proteins it needs until it has some of each of the 21 amino acids. The cell can save the overstock amino acid molecules it doesn’t use and use them for the next thing it needs to build.

Cells make protein products for themselves, such as parts of cell membranes or organelles, or they might produce protein-based hormones that travel to another part of the body. Proteins are very common in structures in the body and make up the matrix molecules that give connective tissues their strength.



Each person’s body has its own needs in terms of energy and metabolic products. The amount of energy your body requires each day is called your metabolic rate. There are two types of measurements of metabolic rate. Your basal metabolic rate is the amount of energy you need just to carry out the functions of being alive—breathing, awareness, digestion, heartbeats, and so on. Your thyroid is the major driver that sets your basal metabolic rate. The hormone thyroxine tells your body what pace it should establish for functions like those mentioned. About 40% of the energy generated in the chemical reactions of metabolism becomes heat that maintains your body temperature.



Our energy needs change over the course of our life. Sometimes it seems like babies don’t do anything except eat and sleep. But they need lots of calories because their bodies are growing quickly. Growth starts to slow down as people become teenagers, and it’s during those years that energy needs start to become different for males and females. By young adulthood, men need 400 more calories per day than women just to maintain basal functions. As we grow older, our bodies slow down. By the time we reach 50 or so, our metabolism has begun to slow down. This is the main reason that older people often have less of an appetite than they did when they were younger.



Of course we need calories above and beyond our basal requirements in order to fuel those other activities. Your total energy expenditure, or TEE, measures how much energy your body uses to complete all your tasks as well as to power basic functions. TEE is greatly influenced by how active you are. It’s beyond whether you went for a run one day. If you exercise consistently, your body adapts to a need for fuel. It uses fuel faster for several hours after you’ve been exercising, and at a rate above basal rate most of the time. If you don’t increase the amount of food you take in, you’ll begin to lose weight. And you don’t have to be a marathon runner to take advantage of this. Even modest exercise, like brisk walking for a half hour a day or making a point to always take the stairs and parking a distance from your destination can make a difference. Adding activity into your life is an easy, safe, fast, and free way to manage your weight.




Reading: Digestive System Conditions



Most (though not all) ulcer sufferers experience a sharp pain in the gut that can almost feel like it’s piercing them. For many years it was thought that ulcers were caused by stress. The reasoning went like this: if someone is overworked, anxious, and stressed out, their gut will produce more gastric juice that will start eating away at the stomach lining. Doctors now know that the culprit in the majority of cases is a bacterium called Heliobacter pylori. Heliobacter is spiral shaped and can burrow its way through the protective mucus lining of the stomach or duodenum and make a home for itself in the cells it makes contact with. If untreated, the bacterium can burrow its way to blood vessels and cause bleeding in the stomach or intestines. It can even get far enough through the wall of a digestive organ to allow gastric juice to leak out into the abdominal cavity. Fortunately, treating ulcers with antibiotics is highly effective, and most people’s ulcers are brought under control easily. Ulcers not caused by Heliobacter are brought on by continual use of certain anti-inflammatory drugs that are hard on the stomach. These ulcers are treated with histamine blockers. Researchers are working on a vaccine against Heliobacter pylori and hope to be able to eradicate it.



There are many circumstances that can cause diarrhea, but they all share the same outcome: not enough water is removed from the feces in the large intestine. If you’ve ever had food poisoning, you know that harmful bacteria can make your digestive system get rid of the infected food in a very big hurry, often sending you running to the bathroom more than once. In developed countries, diarrhea is usually only a problem for a day or two. But in the developing world, where harmful bacteria and parasites are more persistent and can cause major diseases, chronic diarrhea can drain the water and electrolytes from a person’s system. Cholera is an infectious bacterial disease that causes life-threatening diarrhea. Dysentery, caused by a different bacterium or by amoebas, results in bloody diarrhea. These diseases are especially dangerous for children, many of whom die from dehydration because they have no access to treatment.

Diarrhea can also result from stress hormones. The same adrenaline that keeps you nervously biting your nails before a big exam or a much anticipated date also kicks your intestines into peristaltic action. So, even if you don’t have much material lying in wait, anxiety can make you feel nature’s call. People with chronic stress may have elevated levels of adrenaline all the time and suffer from chronic diarrhea.



When feces stay in the intestine too long, it loses too much water and can be painful to expel. If you don’t get enough fiber in your diet, food may move through your intestines more slowly, spending more time than usual in your colon and losing more water. Drinking lots of water helps to prevent constipation. Not getting enough exercise can also slow your peristalsis down. Constipation can be a side effect of certain drugs. Constipation is most common among older people, because their digestive systems have slowed down and all the functions take longer than they used to. The most common cause of constipation in younger people is ignoring the call your body sends to you when it’s time to move your bowels.

Some young people overuse laxatives in an effort to lose or control weight. This is an ineffective strategy because by the time food has reached the large intestine, where laxatives do their work, all the nutrients have been absorbed. But laxative abuse isn’t harmless. Using laxatives regularly can damage your colon and leave you dependent on laxatives to move waste from your bowels.



In Crohn’s disease, the body doesn’t recognize the helpful bacteria in the digestive tract and mounts an inflammation response against them. Initially, people with Crohn’s disease have diarrhea and their appetite may decrease. Eventually, the immune response causes ulcers and scarring in the digestive tract. The walls of the intestines get thicker and stiffen up, making it more difficult to absorb nutrients and water as material moves through the system. For this reason, people with Crohn’s disease may have nutrient deficiencies. At the same time, the diseased tissues in the intestine may affect the strength and frequency of peristalsis, meaning that feces may stay in the intestine longer than they should, leading to constipation. Often people with Crohn’s disease experience both diarrhea and constipation regularly, going back and forth between the two. Over time, Crohn’s disease can lead to dangerous openings or obstructions in the colon that can even require surgery.

About 700,000 people in the United States are affected by Crohn’s disease. The condition usually affects the large intestine and final portions of the small intestine, but it can happen anywhere along the digestive tract. As with many autoimmune disorders, doctors don’t have a clear picture of what causes Crohn’s disease. They do know that it tends to run in families and might be affected by your environment. There’s no cure for Crohn’s disease, but with drugs that help control the immune response, many people with Crohn’s can live normal, functional lives.



Five different viruses, given the letter names A thru E, are known to cause hepatitis, and there may be others. Many people who have hepatitis don’t have symptoms that are easy to pinpoint. They may feel generally tired and under the weather. Some people with hepatitis experience bloating or cramps in the abdomen, and occasionally a patient will note changes to his or her sense of taste or smell. All the hepatitis viruses can cause acute illness that can resolve itself in a few weeks. Some of the viruses, though, can also cause chronic hepatitis which can last years or decades and can lead to liver disease and liver cancer.

Hepatitis C has been of particular concern to public health professionals in the United States, because it is passed through activities that may put a person in contact with an infected person’s blood. Two commons ways hepatitis C is passed among younger people is through tattooing and needle drug use. While there are vaccines for some forms of hepatitis, there is no vaccine for hepatitis C and no treatment for it. Most people who contract it don’t show any symptoms until the diseases has caused liver damage. Then they may have more severe symptoms of jaundice (yellowing of the skin and eyes), vomiting, and fever. Some patients with serious cases of hepatitis C require a liver transplant.



Under normal conditions, your liver gets rid of cholesterol by dissolving it in bile, which then leaves your body with your feces. If you have too much cholesterol in your blood, it can be too much for your bile to absorb, and it can crystalize. The same is true for a pigment found in bile that comes from old, broken down red blood cells. When either of these two substances form crystals, they may get stuck in the gallbladder and block the movement of bile. Some gallstones are so small that they don’t cause much of a problem. A person with these kinds of gallstones might not have any symptoms. Larger gallstones that cause a backup of bile can leave a person feeling pain in his or her abdomen or between the shoulder blades. Sometimes a gallstone goes away or gets flushed out after a short period of time. If it doesn’t and the pain continues, the person may have to have his or her gallbladder removed. Luckily, it’s possible to live normally without your gallbladder, so patients who need theirs removed usually recover completely.



The appendix is a tube of tissue, about 3½ inches long, that extends off the large intestine. Material can move in and out of the appendix from the large intestine, and the appendix contains many bacteria, just like the rest of your large intestine. Until recently, doctors thought the appendix didn’t have a function, but some researchers have begun to explore whether the small tube plays a role in maintaining the bacteria in the large intestine.

We do know that we can live without an appendix. About 1 in every 15 Americans lives without it, in fact! That’s how many people in the United States get appendicitis, or an inflammation of their appendix. It is most likely to occur between the ages of 10 and 30, although anyone can get it at any time.

Appendicitis occurs when the appendix becomes blocked. It can be blocked by stool, an infection, or a foreign body. A blocked appendix becomes inflamed. Unless it is promptly removed by surgery, it will eventually burst, spilling infectious materials into the abdominal cavity. If this cavity then becomes infected, the person can die.




Reading: Nutrition in the NewsStudent Name:_______________________________________________________ Date:___________

Directions: Read through the material and answer the questions at the end of the reading.

In December 2013, these two headlines ran just days apart from each other:

“Vitamin D deficiency may damage the brain, study finds.” Fox news, Dec. 4, 2013

“Low vitamin D is a marker — not a cause — of disease, research review suggests.” MinnPost, Dec. 9, 2013

The first headline states that if you don’t get enough vitamin D, you might suffer brain damage. The second headline shifts the thinking a bit, saying that if you have low levels of vitamin D, it might be a disease that caused those low levels rather than the low levels that caused the disease. In the same week, other headlines touted the many benefits of vitamin D, concluded that vitamin D supplements don’t improve health conditions and warned that too much vitamin D can be dangerous.

If you begin to pay attention to news about nutrition, you’ll find that these conflicting headlines aren’t unusual when a particular nutrient is a hot topic among researchers. Both nutrition and the human body are complicated, and there’s still a lot we’re learning about both of them.

There’s seldom a straightforward answer to a question like “Should I take this particular vitamin?” or “Will this supplement help me?,” and there’s almost always a variety of opinions. Often, the most popular opinion about a nutrition question evolves as researchers learn more about our bodies and the nutrients they need. A good example is how doctors have revised their understanding of and advice to patients about cholesterol over the last 100 years.

Changing Thoughts about CholesterolIn the early 1900s, experiments on rabbits with high cholesterol diets showed that they developed plaque deposits on their arteries. Fifty years later, autopsies on human heart attack victims let doctors see that those plaques were made of a lot of cholesterol. Before long, it became established wisdom that a high cholesterol diet hikes your chances of a heart attack. Out with foods high in cholesterol, like eggs, shrimp, and butter. In the 1980s, researchers began to understand that there are different types of cholesterol, and they pose different risks for heart disease. Eggs, it turns out, are full of “good cholesterol,” and were put back into the “okay” list. Butter, laden with “bad cholesterol,” was still on the “not okay” list, and doctors encouraged patients to use margarine instead.

Fast forward a couple more decades, and the tables are turned. The trans fats in margarine, intended to save us from the saturated fats in butter, were deemed far worse for your heart. In the early 2000s, doctors started telling patients to kick the margarine habit, too. Butter became more acceptable, but olive oil is currently the fat in doctors’ favor.

More recently, in 2011, a study done by researchers at Texas A&M University questioned whether bad cholesterol poses as much risk as it’s been demonized for (though even this study agrees that high levels of cholesterol pose some risk). One study is not enough to prove a point, even though the media may report on it as if it does. There are many factors that might have led to an unusual research result. Other researchers will try to learn more about the result of that and other studies.

In late 2013, the American Heart Association changed its guidelines about how doctors should evaluate a patient’s proper cholesterol levels. Not everyone agreed with these new guidelines, and there remains much debate among physicians about them and about the benefits of drugs that lower cholesterol—a debate that, no doubt, won’t end soon.



Have a StrategyTo help you sort out the hype in this media swirl, it’s good to have a strategy when you hear or read a new story about a particular nutrient or supplement. Here are some things to keep in mind:

When you see an article in the popular media, ask yourself if the headline is making a claim that seems realistic. Remember that research results seldom lead to conclusions that something is a cure or that it will help everyone in a certain way. Sometimes research results will shift doctors’ thinking in subtle ways that bloggers or other writers can blow out of proportion.

Be aware of your own tendency to jump to conclusions that might not be reached in the article. If it says that a supplement “may” help people or that the results point in a certain direction, that means there’s still not enough evidence to know whether or not that benefit is real.

When you hear or read information about a nutrient or supplement, ask these questions:

o Who’s putting forth this information, and do they have a bias about it? For example, if the article is appearing on a website that sells a particular supplement and is exclaiming about the wonderful effects of taking the supplement, then the likelihood of a bias is very strong.

o If you’re reading an article, what is the date? Is this the most current thinking about the topic?

o Is the information based on studies of humans or of lab animals?

Learn more about a claim you hear in the media by reading up on it on medical websites like Mayo Clinic or WebMD or other sites or videos produced by doctors or researchers. You can also look for further information on websites for a medical association that’s interested in the topic, or on a website from the National Institutes of Health. You may find that doctors have different opinions about the research results.

If you hear about a nutrient or supplement that you think can help you, make sure you know specifics about your own condition. Problems like knee pain can be caused by many different things. Learn what you can about yourself as well as about the supplement, if you are debating whether or not to try something.

The bottom line is that the details of health and nutrition news are often moving targets, and there’s usually more to know than what you get from a few news stories. There are also some terms you need to be familiar with order to have perspective on research results.

Some Ideas You Should Be Familiar with: Conflict of interest

A conflict of interest arises when one person or organization may be involved in research or the news about that research in a way that could influence the outcome. For example, a website that sells vitamin supplements has an interest in making news about a particular supplement sound more conclusive than it might actually be. Sometimes the research itself might have questions around conflict of interest. The researcher might be biased toward having the research reach a particular conclusion, or the experiments might be funded by a company or organization that would like to see a certain outcome. Conflict of interest doesn’t always mean that something is wrong, but it means that it’s worth knowing more about whether the outcome of the research was influenced in any way.

Placebos and the placebo affect

A placebo is a fake pill that looks like the real thing. When researchers are trying to understand what affect a nutrient or supplement has, they often give a portion of the patients in the experiment placebos rather than the nutrient. This allows researchers to compare whether people taking the real drug had a different outcome than people who were taking a fake drug. Sometimes people taking the placebo improve, a phenomenon called the placebo effect. Lots of research shows that our brains can have a big influence on what happens in our bodies. While the placebo effect may



seem silly or like it’s all in his head, there’s also a real benefit to it. The placebo effect demonstrates that we have considerable control over how we are experiencing a health issue.

Double-blind clinical trials

In the description of research about a nutrition question, you’ll often see the phrase “double-blind clinical trial.” A double-blind trial is one in which neither the doctor nor the patient know whether the patient is being given a placebo or the real thing. Double-blind trials are considered more reliable because no one involved in them is influenced by knowing who is getting the real drug and who’s not.

Here are a few examples of supplements, nutrients, and foods that have been making headlines.

GlucosamineGlucosamine is a substance your body naturally produces and uses to build new cartilage and repair damaged connective tissue. Many people in the United States take glucosamine supplements in the hope that it will ease the joint pain of osteoarthritis. In 2006, researchers published the results of a study of 1,500 people with osteoarthritis in the knee. The study, published in the British Medical Journal, or BMJ, showed that glucosamine didn’t help them, but it didn’t harm them either. Other doctors continued to study people taking glucosamine supplements, and in 2010, BMJ did a survey of 10 different studies that backed up the conclusion that glucosamine isn’t any more effective than a placebo. After the 2010 report, doctors wrote the journal editors, some supporting the conclusion, and others disagreeing with it.

In late 2013, lawsuits were brought against Rite Aid and GNC, saying that both companies were engaged in false advertising for claiming that glucosamine relieves joint pain and helps heal tissues when research shows this isn’t the case. Still, many people comment on web articles that glucosamine has helped their joint pain, and sales of the supplement were still strong in the United States as of December, 2013. Researchers are likely to continue trying to sort out the effects of glucosamine.

Vitamin DThis vitamin, created when your skin is exposed to sunlight, has seen quite a bit of light itself recently. Doctors have become concerned that Americans don’t have enough vitamin D because we’re outside less often than we used to be, and when we are outside, we often use sunscreen. Not getting enough vitamin D can affect your bones: vitamin D helps the body absorb calcium, which then gets put into the bones as a way of maintaining bone density.

For the last couple of decades, researchers have been looking into other helpful things vitamin D might do for us that have nothing to do with our bones. As of December, 2013, there have been many studies pointing to the notion that sufficient vitamin D can help control cholesterol, improve thinking, fend off depression, lower blood pressure, prevent certain types of cancers, and a host of other benefits. For most of these conditions, vitamin D is still an open question, and it can be hard for a news consumer to sort out what the latest thinking is. You may come across information that seems contradictory. For example, an article on the website WebMD says, “There is recent and mounting evidence that links low levels of the vitamin to an increased risk of….cancers of the breast, colon, prostate, ovaries, esophagus, and lymphatic system.” In a slideshow on that same website, they state, “Headlines tout vitamin D as a way to prevent breast and prostate cancer. But researchers don’t yet have enough evidence to say that the benefits are real. And, vitamin D may boost the risk of pancreatic cancer.”

Neither of these articles is dated, so you can’t tell which information is based on the most recent research. And while the two statements don’t exactly agree with each other, they don’t exactly disagree, either. This reflects the state that vitamin D is in with regard to research about it—it’s inconclusive, and there are lots of studies being conducted in an effort to find more certainty and understanding. Even the National Cancer Institute acknowledges the positive points of the research, but it doesn’t think there’s enough evidence yet to advise people one way or another on whether to take vitamin D as a cancer-prevention strategy.



All the information sources do seem to agree on a few things, though. It’s better to get vitamin D from the sun or from your food than from supplements. Too much vitamin D is problematic, because the vitamin is fat soluble and so can build up in the body. Vitamin D is vital to healthy bone development in babies and children. And the average person can usually make enough vitamin D if he or she gets out in the sun in a T-shirt for 10 minutes a couple of times a week.

Nuts In November 2013, Harvard researchers published the results of a 20-year study comparing mortality among people who eat nuts and those who don’t. What they discovered is that nut eaters have a 20% lesser chance of dying from any cause in a given year of their life than someone who never eats nuts.

The headlines following this announcement often read like this: “Harvard study: Eating nuts may make you live longer.” Reading the articles, you learn that, indeed, it’s true, that nut eaters seem to live longer. About halfway through the articles, though, just as you’re reaching for those almonds, you learn that researchers aren’t sure why nuts convey longevity. It could be something about nuts, of course. Or it could be that people who eat a lot of nuts engage in lots of other healthy practices more often than non-nutters. Or that people who eat a lot of nuts eat them on healthy foods like salads. Or that nuts help with weight control by keeping nut eaters more satisfied than potato chip eaters.

One thing the study demonstrates, though, is that there is indeed some connection between nuts and longer lives. You can bet that researchers will be trying to pinpoint that connection over the next few years. In the meantime, while it’s not certain they’ll extend your life, nuts remain a nutritious and tasty alternative to empty-calorie snacks. And thought researchers can’t explain it yet, they’ve also found that people who eat nuts are slimmer than those who don’t.

ProbioticsAs you have learned, there are trillions of bacteria living in your digestive system, particularly in your colon. They play the important role of keeping other, potentially harmful bacteria out. And they appear to help keep the colon’s functions running smoothly. Since around 2005, researchers in the United States have become quite interested in these bacteria, which have come to be dubbed “good bacteria.” In recent years, a whole lot of products calling themselves probiotics have hit the natural remedy sections of pharmacy shelves, and news about probiotics has hit websites and newspapers.

Probiotics are foods or supplements that contain many of the same helpful bacteria that are found in your gut. While there is a lot of hope that they will be useful for treating many intestinal disorders as well as other wide-ranging conditions, investigations of probiotics are in their early stages and a lot about them and the influence of gut bacteria on the body remains unknown. This isn’t the conclusion you might come to when figures like Dr. Oz and Oprah are producing shows promoting probiotics as a grand, belly-melting approach to weight loss or the cure to autoimmune digestive disorders like irritable bowel syndrome (IBS).

Conditions like IBS are the ones researchers have looked into the most so far when it comes to the usefulness of probiotics. But even in the case of these conditions, there isn’t yet enough information and the studies haven’t followed people for a long enough time to really have a picture of the effect of probiotics. And while good gut bugs may provide some help slimming down, dealing with autism, or reducing cholesterol, the jury is still out on whether that’s always the case. As with vitamin D, we’re bound to see plenty of conflicting information before researchers really have a handle on what probiotics can and can’t do.

Meanwhile, there seems to be no shortage of articles and videos stating that a “balance” of bacteria in the gut can help “general good health.” This may well be true, but such statements leave questions unanswered. Is it known what constitutes a desirable balance of types of bacteria? What is meant by general good health? And perhaps, most importantly, is the statement being made with an underlying assumption that our balance is off, that we don’t have the right proportions of bacteria? Be cautious of



statements that imply these kinds of generalities. Currently, there’s been no comprehensive research into what ratios of gut bugs is best or how many of us need (or don’t need) adjustments.

All of these examples, as well as many other nutrition topics in the news, are confounded by the complexity of the chemistry inside us and our limits to understanding it. Each person’s chemistry is different, and researchers are always learning new ways that nutrients are interacting with other things in our bodies. Some of the studies we hear about in the news have only been done on laboratory animals, and some of the headlines don’t highlight a new study at all but a new perspective on a group of existing research results.

In the end, any news you see about nutrition is just that—new. Magazines don’t write too many articles announcing that “Vitamin D helps build strong bones!” That’s not news. The potential for vitamin D to help our brains and bodies in other ways IS new. And in the field of health, “new” often means our thinking about the topic might be subject to refinement when more new information comes along.

Questions1. Scan the health section of a newspaper (it can be online if you don’t have an actual newspaper handy). Sometimes this is located in the Lifestyles section. What are the headings that you see? Write them here:

2. Choose a headline that touts new findings about a common substance or one of the topics included in this reading. Summarize what the article says about this substance here:

3. Based on what you’ve learned about the importance of long-term, objective research and the effect of bias, do you think this article represents information that is trustworthy? Explain your reasoning.

Some websites you can use for accurate information about vitamins and dietary supplements include:

http://ods.od.nih.gov/factsheets/list-all/

http://www.nlm.nih.gov/medlineplus/druginfo/herb_All.html

http://www.cancer.gov/cancertopics/factsheet/prevention/vitamin-D


http://www.cancer.gov/cancertopics/factsheet/prevention/vitamin-D

http://www.nlm.nih.gov/medlineplus/druginfo/herb_All.html

http://ods.od.nih.gov/factsheets/list-all/



Guide: Digestive System SongStudent Names:_______________________________________________________ Date:___________

Directions: For this assignment, you and your group will write lyrics about a topic covered in this lesson, and sing or rap those lyrics, karaoke style, over music from a song of your choosing. With your group, use this organizer to help you assign tasks and find resources you need to complete your digestive system song. Read the assessment criteria at the end of this guide to make sure you understand how your work will be assessed.

List the names of your group members:

You will also need to choose a secretary and a producer.

The secretary is responsible for:

Keeping track of the source of the song file

Writing down the name and artist of the original song

Keeping track of the lyrics your group comes up with for your song

Typing up and printing out lyrics. She or he will need:

o One copy of the lyrics for each group member when you rehearse the song. Group members will also need these lyrics on the day of the performance.

o One copy of the lyrics to hand in to the teacher on the day of the performance. This copy must be neat, without spelling errors, and include the names of all group members.

The secretary in our group is ____________________________________________

The producer is responsible for:

Locating an instrumental version of the song (without the vocals, like for karaoke) that the teacher can play from a computer or website

Checking the version you’re using to make sure that it’s what everyone thinks it is (artist, radio vs. club mix, etc.)

Having the song queued and ready to rehearse with if there’s a computer available when you do your rehearsal. You can also queue the song using the YouTube app on a smartphone.

Providing the file or URL to the teacher before the day of the performance

The producer in our group is ____________________________________________



Step 1: Choose a Topic for Your SongYour group’s song can be about any aspect of the digestive system. Here are some things to keep in mind when choosing a topic:

Your subject needs to cover the topic as well as provide specific details. Topic examples: describing what happens to a bite of food after we put it in our mouth; the processes of metabolism; the different roles carbohydrates, proteins, and fats play in our bodies; digestive system diseases; macronutrients and micronutrients.

Your topic needs to provide enough material for a couple of verses of information.

Step 2: What Your Song Must IncludeBe sure that your song includes the following:

Terminology used in this lesson that relates to your song topic

Description of both anatomy and physiology aspects of the topic

Original lyrics written by your group

Other things to consider: The song can have a chorus that repeats, but the verses should tell a story and/or provide a

progression of new information.

Everyone in the group should participate in the writing and performance of the song.

Step 3: Choosing Music for Your Lyrics Once you’ve settled on a topic, choose the song that you’ll be singing or rapping to. You’ll most likely want to choose something that has a vocal track and make a karaoke-style file of it to sing/rap the lyrics over.

Things to consider when choosing a song: The song should have a chorus and verses.

Keep it relatively easy to sing or rap so that everyone can participate.

The part you will sing or rap with should be no more than four minutes long (in other words, the chorus and verses you want to sing should fit into four minutes).

Try to avoid songs that have a long music-only break between the chorus and verses you’ll be doing. If you need to include a break, fill it with something such as a short talk or scene about the topic.

Step 4: Writing Your Lyrics Next, write lyrics to your song. You may want to find an online copy of the original lyrics to the song so that you can follow how the song will be structured on the recording (e.g., Is it one verse or two before the chorus?). You may also find the original lyrics inspire some ideas for your new lyrics.

You can find copies of the words to many popular songs on these websites:

http://lyrics.wikia.com/Lyrics_Wiki


http://lyrics.wikia.com/Lyrics_Wiki


http://www.lyricsworld.com/

This site is a lyrics search engine. Type in the song you’re looking for lyrics to, and it will bring up links to a number of pages that have the lyrics.

Once you’ve got the lyrics, decide how many verses you want to include. Unless the verses are quite short, you probably only need two or three.

The chorusThe chorus should:

Contain some overarching ideas or central themes for your song

Be a part of the song that everyone in the group participates in

Your group secretary should be ready with notebook and pen to start writing out the lyrics as your group comes up with them. Make sure you have a complete chorus that’s approved by everyone in the group. Practice singing or rapping the chorus together to make sure it works.

The versesNext, begin writing your verses. You can take a number of different approaches, depending on how you plan to structure your story and perform the song. The verses can:

Tell a story

Describe something that occurs in the body

Be a dialog about the topic between people in the group

Work together in some other way that you come up with

It’s most important that the verses make sense together and address the same topic.

Some performance ideas These are just ideas to get you started, but if your group comes up with something different, great. The main requirement is that everyone in the group takes part in performing.

One verse can be sung by one person, then next by another

Group members can take turns singing lines

Group members can have roles in the song and sing their parts

Two or more group members can harmonize together

One or two group members can beatbox or keep rhythm vocally or with hand gestures. (You could even try doing the song a capella if you use this approach.)

When you have all the lyrics and who will perform them worked out, go over the whole plan for the song with the secretary so that he or she can be sure it’s all properly understood and written down.

The secretary should then type up and print copies of the lyrics so that everyone in the group has a copy for rehearsal.

Step 5: Find Your Song Online You’ll need a copy of your song without vocals—basically, a karaoke version—so that you can sing along with it. The producer in the group can use a number of sources to find an instrumental version of your song. Check these websites:

http://www.karaoke-4-free.com/

https://www.youtube.com/user/TheKARAOKEChannel/videos


https://www.youtube.com/user/TheKARAOKEChannel/videos

http://www.karaoke-4-free.com/

http://www.lyricsworld.com/


You can probably also find an instrumental or karaoke version by just doing a web search for your song title using the words “instrumental” or “karaoke” and “free.”

Since there are often multiple versions of a popular song, the producer should play the version you’ll be using so everyone knows it. The producer should then make a note of the URL and give it to the teacher.

Step 6: Rehearse Your Song Your teacher will give you instructions about where you can rehearse your song. You should also schedule your own rehearsal time outside of class. Make any changes to your performance that you need to. If you need to make any changes to your lyrics, be sure that the secretary knows these changes so that he or she can include them in the lyrics you’ll use in the performance and that you’ll hand in to the teacher.

After rehearsal, the secretary will need to make any changes to the lyrics and print them again if necessary. He or she should also type up and print a copy to be handed in to the teacher that includes all the group members’ names and the title and artist of the original song.

Discuss any props that you want to include (costumes, microphones, things to dance on, etc.) and decide who will bring what on the day of the performance.

Step 7: Perform your song and hand in your lyrics The secretary will need to remember to bring copies of the song lyrics to class.

Check with your teacher to make sure that he or she has the right song queued up for you to sing to. Give the teacher any special instructions needed, such as “fade the music out after the second time we sing the chorus.”

Make sure your assignment meets or exceeds the following assessment criteria: The song lyrics demonstrate thorough understanding of the topic chosen about the digestive

system.

The song lyrics accurately convey anatomy and physiology concepts about the digestive system.

The performance displays evidence that all group members were well prepared for their roles in the performance.

The song lyrics are written up neatly with no spelling errors.


Documents

biolong.weebly.combiolong.weebly.com/.../a_pii_lesson18_studentresource_123115.docx · Web viewThese fats are liquid at room temperature, and liquid in your body. Unsaturated fats