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Digestion
 The process by which the digestive system breaks
down food into molecules that the body can use.
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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.
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Enzymes
 The chemicals involved in breaking down food
molecules.
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Absorption
 The process by which nutrients pass through the
lining of the digestive system into the blood.
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Elimination
 Materials not absorbed are eliminated from the
body as waste.
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The beginning of digestion
Mechanical digestion
 The Jaw
 Teeth tear, crush, and grind food
 Tongue pushes food around
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Chemical digestion
Enzymes 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
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Location
3 main parts
 Nasopharynax
 Oropharynax
 Laryngopharynx
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Behind nasal and oral cavity
Nasopharynax- behind the nasal cavity
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Oropharynx- part you can see through the
mouth
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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
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Connects throat (pharynx) with the stomach
Muscular tube
10 inches long
Lined moist pink tissue called Mucosa
Runs behind windpipe (trachea) and heart,
but in front of the spine.
Passes through diaphragm
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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
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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
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20 feet long, 1 inch diameter
Where 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
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Liver, Gallbladder, and Pancreas also help in
digestion
Liver
 Produces bile which breaks up large fat droplets that
clump together
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Gallbladder
 Storage for bile. As food leaves your stomach, the
gallbladder releases the bile
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Pancreas
 Releases enzymes into the small intestine for the
breakdown of carbohydrates, proteins and fats
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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
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http://www.youtube.com/watch?v=OYWVbt6
t2mw
1.
2.
3.
4.
5.
What is the process that physically broken
down into smaller pieces?
What are the Chemicals involved in breaking
down food molecules
What is the beginning of digestion
The average person produces 1.5 liters of
this per day
What is the name of the thick liquid that
moves along into the small intestines
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 Bile
9) Muscular tube that connects the throat with
the stomach
10) The wave like function that moves food
along to the intestines
6)