Digestion and Nutrition

Introduction

Digestion: mechanical and chemical breakdown of food into forms the cell membrane can absorb Alimentary canals: extends

from the mouth to the anus Mouth, pharynx, esophagus,

stomach, small intestine, large intestine, and anal canal

Several accessory organs: release secretions into the canal Salivary glands, liver,

gallbladder, and pancreas

General Characteristics

9-meter muscular tubeStructure of the Wall

Mucosa: mucous membrane Inner most layer Protects the underlying tissue Carries out secretion and absorption Epithelium, connective tissue, and smooth muscle Tiny folds and projection in the lumen, passageway

Increase absorption through increased surface area Glands: secrete mucus and digestive enzymes

Structure of the Wall

Submucosa Loose connective tissue, glands, blood vessels, lymphatic

vessels, and nerves organized into plexus Vessels nourish surrounding tissue and carry away absorbed

nutrients awayMuscular Layer

Moves the tube Smooth muscle tissue and some nerves organized into a plexus

Serosa: serous layer Visceral peritoneum: outer covering of the tube Protect underlying tissue Secrete serous fluid

Moistens and lubricates the tube’s outer surface

Layer of Digestive Tract

Tube Movement

Mixing Movement smooth muscles in small segments of the tube

contract rhythmically Full stomach: movement mixes the food and digestive

juices

Propelling Movement Peristalsis: wave-like motion

Ring of contraction Push food along the tube

Mouth

Receives food Begins digestion

mechanically reducing the size of solid particles

mixing particles with salivaOral Cavity: chamber

between palate and tongue

Vestibule: narrow space between the teeth, cheeks, and lips

Cheeks and Lips

Cheeks outer layers of skin pads of subcutaneous fat muscles associated with expression and chewing inner linings of moist stratifies squamous epithelium

Lips: highly mobile structures that surround the mouth opening Skeletal muscles Sensory receptors: temperature and texture

Red color: due to abundance of blood vessels near their surface

Tongue

Covered with mucous membranesFrenulum: connects the midline of the tongue to

floor of the mouthSkeletal Muscle

Mix food particles with saliva Move food toward the pharynx

Papillae: rough projections on surface Provides friction to handle food Contain taste buds

Root: posterior region Connected to hyoid bone Lingual tonsils: rounded masses of lymphatic tissue

Palate

Roof of oral cavity Hard plate: anterior part Soft plate: muscular arch, which extends downward to

cone-shaped projection, the uvula During swallowing, drawn upwards Action closes the opening between the nasal cavity and

pharynx Palatine Tonsils: back of mouth, on either side

Tonsils of tonsillectomy Pharyngeal Tonsils: adenoids

Posterior wall of pharynx

Tonsils and Adenoids

Teeth

Primary Teeth: 20 deciduous teeth 6 months to 2 or 4 years

Secondary Teeth: 32 permanent teeth 6 years to 17 or 25 years

Break pieces of food into smaller pieces Increases surface area digestive enzymes

Teeth

Crown: projects beyond the gum Enamel: covers the crown

Ca salts; hardest substance in the body

Dentin: beneath the enamel; bone like

Root: anchored to the jaw

Teeth

Incisors: chisel-shaped Bit off large pieces of food

Cuspids: cone-shaped Grasp food and tear

Bicuspids and Molars somewhat flattened surface Grinding food particles

Salivary Gland

Secrete saliva Moistens food particles, helps bind them, and begins

the chemical digestion of carbohydrates Solvent allowing food to be tasted Helps cleanse the mouth and teeth

Salivary Secretions

Serous Cells: water fluid that contains amylase Splits starch and glycogen molecules

Mucous Cells: thick liquid called mucus Binds food particles Lubricated during swallowing

Parasympathetic Nerves secrete watery saliva see, smell, taste, or think about food Food that looks, smells, or tastes unpleasant inhibits

this

Major Salivary Glands

Parotid Glands: largest, anterior to each ear Secrete a clear, watery fluid rich in amylase

Submandibular Gland: floor of the mouth on the inside surface of the jaw Predominantly serous and some mucous

Sublingual Gland: floor of the mouth, inferior to the tongue Smallest Primarily mucous

Pharynx, Esophagus, Stomach, and Pancreas

Pharynx

Cavity posterior to the mouth from which the tubular esophagus leads to the stomach Pharynx nor esophagus digests food

Pharynx

Structure of Pharynx: connects the nasal and oral cavities with larynx and esophagus Nasopharynx: provides a passage way for air during

breathing Oropharynx: passageway for food moving downward

from mouth and for air moving to and from the nasal cavity

Laryngopharynx: passageway to esophagus

Swallowing Mechanism

1st stage: voluntary food is chewed and mixed with saliva Tongue rolls mixture into a mass, bolus and forces it

into the pharynx2nd stage: food stimulates sensory receptors

around the pharyngeal opening Triggers swallowing reflex Epiglottis: flap-like structure that closes the tops of

the trachea3rd stage: peristalsis transports the food in

the esophagus to the stomach

Epiglottis

Esophagus

Straight, collapsible tube about 25 cm longFood passageway from the pharynx to the

stomach Mucous Glands: secretions moisten and lubricate the

tube’s inner lining Lower esophageal sphincter: close the entrance to the

stomach Prevents regurgitation of stomach contents

Stomach

J-shaped, pouch-like organ inferior to the diaphragm upper left portion of abdominal cavity1 L capacityFunctions:

Receives food from the esophagus Mixes food with gastric juices Initiates protein digestion Carries limited absorption Move food into small intestine

Parts of the Stomach

Cardiac: small area near the esophageal opening

Fundic: balloons above the cardiac portion Temporary storage area

Body: main partPyloric: narrows as it

approaches the sm. Intestine

Pyloric sphincter: muscle valve controlling gastric emptying

Gastric Secretions

Mucous Membrane of stomach contains many gastric pits, ends of gastric glands Mucous cells: large quantities of thin mucus Chief cells: digestive enzymes Parietal cells: HCl

Gastric Secretions

Digestive Enzymes Pepsin: protein

Mucus and other alkaline secretions prevent pepsin from digesting the stomach itself

Intrinsic Factor: need for B12 absorption

Regulation of Gastric Secretions and Absorption

Gastric juices are continuously produced, but the rate varies Parasympathetic impulses and the hormone gastrin

enhance gastric secretion Food moving into the sm. intestines inhibits secretions

Gastric absorption: only a few substances in small quantities Water, certain salts, alcohol, and some lipid-soluble

drugs

Mixing and Empting Actions

Chyme: mixture of food particles and gastric juices Production aided by movement of stomach Peristaltic waves push chyme toward pyloric sphincter Stomach relax with accumulation of chyme, a little at

a time, is pushed into the small intestines

Mixing and Empting Actions

Liquid pass quite rapidlySolid remain until they are well mixed

Fatty foods remain 3-6 hours Proteins: quicker Carbohydrates: faster than protein and fats

As food enters the duodenum, accessory organs add their secretions Pancreas, liver and gallbladder

Pancreas

Secretes pancreatic juice into the duodenum Contains enzymes to digest carbohydrates, fats,

nucleic acids, and proteins Pancreatic amylase: carbohydrate digesting enzyme Pancreatic lipase: fat digesting enzyme Nucleases: nucleic acid digestion enzyme Trypsin, chymotrypsin, and carboxypeptidase: protein

digesting enzymes

Pancreas Regulation

Stimulation the release of pancreatic juices Nervous and endocrine system Food in duodenum

Pancreatic juices are high in bicarbonate ions Neutralizes chyme Intestinal contents to be alkaline

Liver, Small Intestines, and Large Intestines

Liver

Located in the upper right quadrant of the abdominal cavity

Fibrous capsule encloses the liver

Connective tissue divides the organ into a large right lobe and a smaller left lobe Each lobe is separated into tiny

hepatic lobules Liver’s functional units

Bile canals carry bile from hepatic lobules to hepatic ducts

Liver Function

Metabolizes carbohydrates, lipids, and proteins

Stores some substancesFilters bloodDestroys toxinsSecretes bile

Important in digestion

Bile

Bile salts, bile pigments, cholesterol, and electrolytes Only bile salts have digestive functions Bile salts emulsify fats and aid in the absorption of

fatty acids, cholesterol, and certain vitaminsGallbladder stores bile between mealsCholecystokinin from the small intestine

stimulates bile’s release Enters the duodenum

Small Intestine

Receives secretions from the pancreas and liver

Completes nutrient digestionAbsorbs the products of digestionTransports the residues to the large intestineParts

Duodenum Jejunum Ileum

Small Intestine

The wall is lined with villi Increase in surface area Aid in mixing and absorption Intestinal glands are located between the villi

Secretions of the small intestine Mucus and digestive enzymes Digestive enzymes split sugars,

proteins, and fats Gastric juice, chyme, and reflexes

stimulated by distention of the small intestine wall stimulate secretion

Absorption

Microvilli: absorb monosaccharides, amino acids, fatty acids, and glycerol

Fat molecules with long chains enter the lacteals of the villi

Fatty acids with short chains enter blood capillaries in villi

Movement

Mixing and peristalsisIleocecal sphincter: controls movement

between small and large intestines

Large Intestines

Parts Cecum, colon, rectum, and anal canal Colon is divided into ascending, transverse,

descending, and sigmoid portionsUnique layer of longitudinal muscle fibers

arranged in distinct bands

Large Intestines

Functions: Little or no digestive function Secretes mucus Absorbs water and electrolytes Forms and stores feces

Movement: similar to small intestine Mass movement occurs two to three times a day

Feces: water, undigested material, electrolytes, mucus, and bacteria Color is due to bile salts that have been altered by

bacteria

Nutrition

Nutrition

Process of ingestion and utilization of necessary food substances, or nutrients

Carbohydrates: organic compounds that primarily supply cellular energy

Sources: starch, glycogen, disaccharides, and monosaccharides Cellulose: polysaccharide that

humans cannot breakdown

Carbohydrates

Utilized for: Oxidation energy release from

glucose Excess glucose is stored as

glycogen or converted to fat Most carbohydrates supply

energy Some cells require a

continuous supplyRequirements: humans can

survive with a wide range of carbohydrate intake

Lipids

Supply energy and used to build cell structure

Sources: triglycerides from plants and animals Animals: most cholesterol

Lipids

Lipid Utilization Liver and adipose tissue control triglyceride

metabolism Linoleic acid: essential fatty acid

Corn, cotton seed, and soy oil

Lipid Requirements: amounts and types are unknown Fat intake must be sufficient to carry fat soluble

vitamins A,D,E,K

Proteins

Serve as structural materials, function as enzymes, and provide energy

Sources: meats, dairy products, cereals, legumes

Requirements Supply essential amino acids and nitrogen for the

synthesis of nitrogen containing molecules

Vitamins

Essential for normal metabolic processesBody cells cannot synthesize adequate

amountsFat soluble: A, D, E, K

Carried by lipids and affected by the same factors that influence lipid absorption

Resist the effects of heat; cooking has no effectWater-soluble: B and C vitamins

B vitamins: oxidizes carbohydrates, lipids, and proteins

Cooking or food processing destroys some water-soluble vitamins

Minerals

Elements other than carbon that are essentialMost minerals are in the bone and teethUsually in organic compounds

Some are in inorganic compounds or free ionsFunctions: structural material, enzymes, and

vital roles in metabolic processesMajor Minerals: Ca, P, K, S, Na, Cl, and MgTrace Elements: Fe, Mn, Cu, I, Co, Zn, F, Se,

Cr

Adequate Diet

Provides sufficient energy and essential nutrients to support optimal growth, maintenance, and repair of tissue

Impossible to design a diet adequate for everyone

Malnutrition: poor nutrition due to the lack of foods or failure to make the use of the available foods

Eating Disorders

Eating Order Statics

8 million Americans have an eating disorder 7 million women and 1 million men

1 in 200 American women suffers from anorexia 2 to 3 in 100 American women suffers from bulimia Nearly half of all Americans personally know someone with

an eating disorder (Note: One in five Americans suffers from mental illnesses.)

An estimated 10 – 15% of people with anorexia or bulimia are males

ADOLESCENTS Anorexia is the 3rd most common chronic illness among

adolescents 95% of those who have eating disorders are between the ages

of 12-25 50% of girls between the ages of 11-13 see themselves as

overweight 80% of 13-year-olds have attempted to lose weight

MORTALITY RATES

Eating disorders have the highest mortality rate of any mental illness

A study by the National Association of Anorexia Nervosa and Associated Disorders reported that 5 – 10% of anorexics die within 10 years after contracting the disease; 18-20% of anorexics will be dead after 20 years only 30 – 40% ever fully recover

The mortality rate associated with anorexia nervosa is 12 times higher than the death rate of ALL causes of death for females 15 – 24 years old.

20% of people suffering from anorexia will prematurely die from complications related to their eating disorder, including suicide and heart problems

Treatment

Only 1 in 10 people with eating disorders receive treatment About 80% of the girls/women who have accessed care for their

eating disorders do not get the intensity of treatment they need to stay in recovery – they are often sent home weeks earlier than the recommended stay

Treatment of an eating disorder in the US ranges from $500 per day to $2,000 per day. The average cost for a month of inpatient treatment is $30,000. It is estimated that individuals with eating disorders need anywhere from 3 – 6 months of inpatient care. Health insurance companies for several reasons do not typically cover the cost of treating eating disorders

The cost of outpatient treatment, including therapy and medical monitoring, can extend to $100,000 or more

http://www.huffingtonpost.com/2010/12/29/isabelle-caro-dead-anorexic-model_n_802424.html

Amputation Diet

Procedure Estimated Immediate Weight LossClip finger and toenails 1 ounce maximum

Haircut 2-6 ouncesDrastic Haircut / Headshave 4-12 ounces

Trim Body Hair 1 oz. (ladies) 3 oz. (men) 24 lbs (Greek men)

Remove a wart 1 oz.Take a diuretic 1-3 pounds (temporary)Take a laxative 1-2 pounds (temporary)

Colon Therapy / Take an Enema 2-3 pounds (temporary)Poop 0-2 pounds (temporary)

Run a marathon on a hot day 3 lbs (women), 5 lbs (men) (temporary)Amputate your arm 10-25 lbs (way too permanent)Amputate your leg 15-45 lbs (again, not advised)

Vascetomy none.Take a big pee. up to 1.5 pounds

Take a big dump up to 2.5 pounds

Amputation Diet

Procedure Estimated Immediate Weight LossGo barefoot 1-2 poundsGo Naked 1-8 pounds (summer vs. winter)

Contact lenses vs. Glasses 0.3 poundsNo liquids all day 1-2 poundsNo food all day 2-3 poundsNo salt all day 0-1 pound

Don't wear underwear 1 oz. (thong)-2 lbs. (granny panties)Exfoliating face wash nothing.

Liposuction 10 lbs maximum per surgeryDonate a kidney 3 pounds.

Breast Reduction Surgery 5-15 pounds typically

Things that Remind Me of My Grandmother

1.If you eat something and no one sees you eat it, it has no calories. 2.If you drink a diet soda with a candy bar, the calories in the candy

bar are cancelled out by the diet soda. 3.When you eat with someone else, calories don't count if you don't

eat more than they do. 4.Food used for medicinal purposes NEVER count, such as hot

chocolate, brandy, toast and Sara Lee Cheesecake. 5.If you fatten up everyone else around you, then you look thinner. 6.Movie related foods (Milk Duds, Buttered Popcorn, Junior Mints,

Red Hots, Tootsie Rolls, etc.) do not have additional calories because they are part of the entertainment package and not part of one's personal fuel.

7.Cookie pieces contain no fat-- the process of breaking causes fat leakage.

8.Things licked off knives and spoons have no calories if you are in the process of preparing something. Examples are peanut butter on a knife making a sandwich and ice cream on a spoon making a sundae.

Things that Remind Me of My Grandmother

9.Foods that have the same color have the same number of calories. Examples are: spinach and pistachio ice cream; mushrooms and white chocolate. NOTE: Chocolate is a universal color and may be substituted for any other food color.

10.Foods that are frozen have no calories because calories are units of heat. Examples are ice cream, frozen pies, and Popsicles.

11. Foods eaten while watching a major event on television do not count. Major events include: Superbowl, Hockey Finals, Indy 500.

12. Powerbars and other type energy bars make you thinner. In all my years of exercising (at least three times a year) I have only seen thin people eating energy bars. Ergo (therefore) they must make you thin.

13. Snickers is the same as an energy bar (see #12) 14. Tasting other people's food does not add to your calorie count. 15. Containers of food that list the number of servings as greater

one are lying. Every container includes one serving. Half gallon of ice cream, box of cereal, bottle of soda, bag of chips are all one serving.