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The Digestive SystemPresented By:Mrs. Nelson
Nutrition Nutrition is the study of how food affects
the function of living organisms. Food contains nutrients. Nutrients provide the energy and
materials organisms need. If organism’s cells are not provided with
nutrients, the cells will not function properly.
Poor diet = poor cells
Six Categories of NutrientsEnergy Suppliers
Carbohydrates Lipids Proteins
Non-Energy Suppliers
Water Vitamins Minerals
Carbohydrates Glucose is main source of carbohydrates
for animals. Glucose is easily converted to ATP. Glucose is found in fruits, vegetables,
grains, and dairy foods. Many foods contain cellulose also known
as “fiber.” Important for helping push food through the digestive tract.
Energy from food is measured in “calories.”
Lipids Provide twice as much energy as carbohydrates. Important for…
1) Making cell membranes2) Hormone production3) Myelin production4) Protect organs and insulate body
Take long time to digest. Too much fat in diet= excess energy = fat
deposits. Saturated fats (solid, contain single bonds)
contain LDL cholesterol and build up on arteries.
Proteins Proteins made of amino acids. 20 different amino acids. Body can make 12/20 amino acids. The other eight must come from food are
called “essential amino acids.” Proteins are materials needed for…
1) growth and repair.2) skin and muscles.3) regulatory (enzymes- insulin) and transport functions (hemoglobin– RBC).
Water Most important nutrient. Lubricates areas of body (blood, lymph,
plasma, etc.) Coolant for body. Solvent for digestion. Provides fluid environment for cells. Body needs intake 1L of water a day.
Minerals Inorganic (not made by living things). Plants absorb minerals. Animals eat plants to get minerals. Minerals are only needed in trace amounts
by the body. Iron (hemoglobin RBC) Calcium (bones and teeth) Sodium/Potassium (nerve and muscle
function) Magnesium/Zinc/Iodine
Vitamins Organic (made by living things). Help regulate body processes. Most obtained from food. Vitamin K- made by bacteria in digestive tract. Vitamin D- synthesized by skin cells when
exposed to sunlight. 2 types vitamins…
1) Fat soluble- can be stored in fatty tissues for future use (A, D, E, K)
2) Water soluble- dissolve in water and can not be stored by body (C, B)
Importance of Various Vitamins A, C, D, E, K, Folic Acid, B12
Helps RBC mature
The Digestive System System is responsible for breaking down
food so that nutrients can be absorbed by the bloodstream.
The “alimentary canal” is the pathway which food travels while it is digested.
The Alimentary Canal Mouth Esophagus Stomach Small intestine Large intestine Rectum
* The liver, pancreas, and gallbladder are parts of the digestive system but are not parts of the alimentary canal.
The Mouth Chemical digestion –saliva contains
enzyme amylase that digests carbohydrates (starches)
Mechanical digestion- chewing
Esophagus
Tube from back throat to stomach.
Trachea (lungs) and esophagus are next to each other.
Epiglottis prevents food from going down the wrong tube.
Peristalsis- muscular contractions pushes food down esophagus.
Stomach Chemical/mechanical
digestion. Hydrochloric acid and
pepsin (enzyme) break down proteins to amino acids.
Stomach lining contains mucus.
Mucus protects stomach from acid (ulcers).
Sphincter muscles (cardiac and pyloric) control what enters and leaves the stomach (heartburn).
Small Intestine 20 ft. Remaining carbohydrates
and proteins are broken down.
All lipids are digested here. Connected to liver and
pancreas.
Liver and PancreasLIVER JOBS
Makes and secretes bile (needed digest lipids).
Bile is stored in the gall bladder.
Detoxifies drugs and alcohol.
PANCREAS JOBS Regulates blood
sugar. Secretes digestive
enzymes into small intestine.
Neutralizes stomach acid as it enters the small intestine (bicarbonate).
Small Intestine (cont.) After all nutrients are
digested, they are absorbed. This is the major job of this organ.
S.I. contains lots of capillaries.
Mesentary.
Large Intestine All proteins,
carbohydrates, and lipids have been removed from food by the time it gets here.
Water is absorbed (diarrhea).
Vitamins are absorbed. Feces is undigested
food passes out rectum and anus.