Download The Digestive System - Field Local Schools

The Digestive System
3 Functions of the Digestive System
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Digestion
○ The process by which the digestive system
breaks down food into molecules that the body
can use
■ Mechanical
● Foods are physically broken apart
into smaller pieces (Chewing)
■ Chemical
● Chemicals produced by your body
break large molecules into small ones
(Enzymes)
3 Functions of the Digestive System
● Absorption
○ The process by which nutrients pass through the
lining of your digestive system into your blood
■ Blood
● Transports the nutrients throughout body
● Elimination
○ Materials not absorbed are eliminated from the
body as wastes
Structures of the
Digestive System
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Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine
Liver
Gallbladder
Pancreas
Structures of the Digestive System
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Mouth
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Pharynx
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Mechanical Digestion
■ Teeth tear, crush, and grind your food
■ Tongue pushes food around
Chemical Digestion
■ Enzymes in saliva begin to breakdown starches
■ Moistens food so it can be swallowed
Upper portion of the throat
Junction between digestive tract and respiratory system
Epiglottis
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Seals off trachea(windpipe) preventing food from entering the lungs
Structures of the Digestive System
● Esophagus
○ Muscular tube that connects the
pharynx to the stomach
■ Peristalsis
● Muscle contractions push
food through esophagus
to stomach
● Continue throughout the
digestive system
Structures of the Digestive System
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Stomach
○ Muscular pouch in the abdomen
■ Mechanical Digestion
● Layers of muscle produce churning motion
● Mixes food with fluids like a washing machine
■ Chemical Digestion
● Gastric juice containing hydrochloric acid is released
● Hydrochloric acid helps break down food
● Pepsin (enzyme) breaks down proteins and converts to amino acids
● Stomach lining is coated with mucus
● Mucus protects stomach lining from contact with hydrochloric acid
○ Peptic Ulcer - hole in stomach lining
Chyme
○ Thick liquid that moves to the small intestine
Structures of the Digestive System
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Small Intestine
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Liver
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Produces bile, a substance that physically breaks up
large fat droplets that clump together
Gallbladder
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20 foot long tube, where most chemical digestion
and absorption of nutrients takes place
Stores and releases bile into the small intestine
Pancreas
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Secretes enzymes into the small intestine
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Enzymes break down carbohydrates, protein, and
fats
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After enzymes break down food, nutrients can be
absorbed
Structures of the Digestive System
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Villi
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Millions line the small intestine
Finger like projections that absorb nutrients
Nutrients pass from villi to your blood, where
they are transported throughout the body
Large Intestine
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Undigested material and unabsorbed water is
pushed to the large intestine
5 feet long
Water is absorbed into blood
Waste material is compressed and pasted to the
rectum