Transcript Digestive System

Digestive
System
- breaks down food
into molecules the
body can use,
getting rid of
undigested
molecules
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• peristalsis – muscle contractions, moves
food through tract
• sphincters - valves; regulate passage of material
between chambers
The Digestive Tract
Gastrointestinal Tract (GI)
• Mouth –
Teeth – physical
saliva – moistens and lubricates food
- amylase – begins the breakdown of carbohydrates
(chemical)
• Pharynx –back of throat
– food (bolus) triggers reflex
– epiglottis – flap of cartilage, covers trachea
• Esophagus – connect mouth to stomach
• Stomach –
* physical and chemical digestion
*gastric juice secreted by cells of
stomach
hydrochloric acid (HCl)–
breaks down protein
strands
into single
strands
pepsin – enzymes; proteins
into amino acids
*peristalsis
• Small intestines
completes digestion
absorption of nutrients
*duodenum – 1st part of small
intestines; receives secretions
from pancreas, liver and
gallbladder
bile – produced by liver and
stored in gallbladder - breaks
down fats
enzymes complete digestion
of carbs, proteins and lipids
lipases -fats
Absorbtion of nutrients to
the blood
villi – fingerlike
projections; cover lining
of small intestines.
-increase surface area for
absorption
Large intestines - colon
water absorption
compacting undigested material – waste (feces)
Rectum
storage and elimination of waste
• Digestive System also includes the
liver and the pancreas
– Pancreas
• Produces digestive enzymes
• insulin
– Liver
• Digested molecules absorbed into
bloodstream transported to liver
• Maintains blood sugar levels
•
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Liver
• Nutrients transported to the liver
• Stores extra sugar as glycogen
• converts glycogen back to glucose to use for
energy
• Modify amino acids
– Ex: make amino acids and proteins
• Detoxifies poison
– Stores poisons unable to change
• Cirrhosis – scarring of the liver
Ex: