Digestion:What your body does with food

Unit 1 Topic 6

CATALYST:

Can you match a letter to the following body parts:

Small intestine

Esophagus

Stomach

Large intestine

Liver

Pancreas

Stages of food processing

• Ingestion

• Digestion– Mechanical

– Chemical

• Absorption

• Elimination

Mouth (oral cavity)

• Functions– mechanical digestion– chemical digestion– Saliva also contains…

• mucus • buffers • anti-bacterial chemicals

Swallowing

• Epiglottis

• Peristalsis

Stomach• Functions

–disinfect food–food storage–digests protein–mechanical digestion

But the stomach cells contain protein!What stops the stomach from digesting itself?

mucus secreted by stomach cells protects stomach lining

Small intestine• Functions

– Chemical digestion– Absorption

This iswhere all thework is done!

Absorption in Small Intestines• Absorption through villi & microvilli

SMALL INTESTINES6 meters long,but can stretchto cover a tennis court

Accessory organ: Pancreas • Produces digestive enzymes that

function in the small intestine for chemical digestion

• Also produces buffers

Accessory organs: Liver & Gall Bladder

• Liver produces bile• Gallbladder stores bile

• Function– re-absorbs water– compact waste for elimination

Large intestines (colon)

You’ve got company!• Living in the large intestine is a

community of helpful bacteria– Escherichia coli: E. coli

• digest cellulose

• produce vitamins – vitamin K & B vitamins

• BUT generate gases– by-product of bacterial metabolism – methane, hydrogen sulfide