- breaks down food into molecules the body can use, getting rid of undigested molecules

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htm

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Digestive System

• peristalsis – muscle contractions, moves food through tract

• sphincters - valves; regulate passage of material between chambers

The Digestive TractGastrointestinal 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

• 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: