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.