Transcript Digestive System

Digestive
System
- breaks down food
into molecules the
body can use,
getting rid of
undigested
molecules
http://health.howstuffworks.com/adam200086.htm
http://health.howstuffworks.com/adam200088.htm
• 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)–
unfolds the proteins (exposing
the bonds to be broken later)
pepsin – enzymes breaks down
proteins into polypeptides;
Works in the acidic envioronment
*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
lipase – further breaks down
fats
• Trypsin – produced by the pancrease,
• Breaking down polypeptides into amino acids
• amylase
– Pancreatic amylase further breaks down carbs
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
•
http://www.innerbody.com/image/digeov.html
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: