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Maryville University Nursing Students
The Digestive System
DigestionDigestion
The process by which the digestive system breaks down food into molecules that the body can use.
2 types of digestion Mechanical digestion-foods are
physically broken down into smaller pieces.
Chemical digestion-chemicals produced by the body break larger molecules into smaller ones.
Digestion (cont)
Enzymes The chemicals involved in breaking down
food molecules.Absorption
The process by which nutrients pass through the lining of the digestive system into the blood.
Elimination
Elimination Materials not absorbed are eliminated
from the body as waste.
The Mouth
The Mouth
The beginning of digestionMechanical digestion
The Jaw Teeth tear, crush, and grind food Tongue pushes food around
Saliva
Chemical digestionEnzymes in saliva begin to
breakdown starches in food.Saliva also moistens the bite of food
into a slippery mass called a bolus that can be easily swallowed
Approximately 1.5 L of saliva is secreted daily
The Pharynx
The pharynx
Location3 main parts
Nasopharynax Oropharynax Laryngopharynx
Behind nasal and oral cavityNasopharynax- behind the nasal
cavity
The Pharynx
Laryngopharynx- the bottom part of the Pharynx
Back part of pharynx continues downward into the esophagus
The front part leads to the larynx (voice box)
During swallowing the entrance of the larynx is covered by the epiglottis
The Esophagus
The Esophagus
Connects throat (pharynx) with the stomach
Muscular tube10 inches longLined moist pink tissue called
MucosaRuns behind windpipe (trachea) and
heart, but in front of the spine.Passes through diaphragm
Upper Esophageal Sphincter
The Stomach
Stomach Mechanical Digestion
Three layers of stomach muscle cause a “churning motion”
Chemical Digestion Pepsin ▪ Breaks down proteins▪Works well with hydrochloric acid ▪Stomach is protected by a lining of mucus to aid in protection of itself from the acid
Stomach
Digestion normally occurs over a few hours
Most proteins have been chemically digested into shorter chains of amino acids
Peristalsis moves food along into the small intestine Food becomes a thick liquid called
chyme
Intestines
Small intestine
20 feet long, 1 inch diameterWhere most of the chemical
digestion and nutrient absorption takes place
Fingerlike projections along the lining called villi which absorb nutrient molecules
Nutrients pass onto the blood vessels on the villi and pass on into the blood stream and throughout the body
Digestion (cont) Liver, Gallbladder, and Pancreas also help in
digestion Liver
Produces bile which breaks up large fat droplets that clump together
Gallbladder Storage for bile. As food leaves your stomach,
the gallbladder releases the bile Pancreas
Releases enzymes into the small intestine for the breakdown of carbohydrates, proteins and fats
Large Intestine (Colon) 5 ft long, 3 inches in diameter Vitamin production through the natural bacteria
living in the lining of the large intestine Most of body’s requirements of Vit K
Most nutrients have been absorbed when food enters large intestine
As it moves through the large intestine, most of the remaining water is absorbed into the bloodstream
It ends at the rectum, a short tube where waste material is compressed into solid form known as feces or stool and eliminated through the anus
http://www.youtube.com/watch?v=OYWVbt6t2mw
1. What is the process that physically broken down into smaller pieces?
2. What are the Chemicals involved in breaking down food molecules
3. What is the beginning of digestion4. The average person produces 1.5
liters of this per day5. What is the name of the thick liquid
that moves along into the small intestines
6) What is the muscle flap called that covers the opening of the larynx during swallowing
7) What are the fingerlike projections that absorb nutrient molecules
8) What Stores Bile9) Muscular tube that connects the
throat with the stomach10)The wave like function that moves
food along to the intestines
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