Regents Biology

Digestive SystemMidterm Content

Human digestive system

Mouth

Teeth - mechanical digestion break up food

Saliva - chemical digestion amylase enzyme digests starch

All thatin spit

Esophagus –Swallowing (& not choking)

Epiglottis flap of cartilage closes trachea (windpipe) when swallowing food travels down esophagus

Peristalsis

involuntary muscle contractions to move food along

Small intestine Functions

digestion digest carbohydrates

amylase from pancreas

digest proteins trypsin & chymotrypsin from pancreas

digest lipids (fats) bile from liver & lipase from pancreas

absorption nutrients move into body cells by:

diffusionactive transport

Absorption in Small Intestines Nutrient absorption through villi

finger-like projections increases surface area for absorption

SMALL INTESTINES6 meters long,but can stretch

to cover a tennis court

Liver & Gall Bladder Produces bile

breaks up fats gallbladder only stores bile

that’s why you can have your gall bladder removed

bile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

bile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

Function re-absorbs water

not enough water re-absorbed Diarrhea

too much water re-absorbed constipation

Large intestines (colon)

Rectum Last section of large intestines

eliminate feces what’s left over?

undigested materials mainly cellulose from plants called roughage or fiber keeps everything moving & cleans out

intestines

masses of bacteria

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

community of helpful bacteria Escherichia coli: E. coli

Help digest cellulose digests fruits & vegetables

produce vitamins vitamin K & B vitamins

BUT generate gases by-product of bacterial metabolism methane, hydrogen sulfide STINKY!

stomachkills germs break up fooddigest proteinsstore food

mouthbreak up fooddigest starchkill germsmoisten food

small intestinesbreakdown food

- proteins- starch- fats

absorb nutrients

pancreasproduces enzymes to digest proteins & carbs

liverproduces bile

- stored in gall bladderbreak up fats

large intestinesabsorb water

Trivia 1

The function of the digestive system is to . . .

a.chemically break down food

b.absorb nutrient materials

c.mechanically break apart food

d.all of the above

Trivia 2

The villi of the small intestine allow for an increase in the rate of . . .

a.nutrient absorption

b.acid production

c.cellulose digestion

d.bile production

Trivia 3

Enzymes in saliva begin the chemical digestion of . . .

a.fat

b.Protein

c.carbohydrates

d.vitamins

Trivia 4

Where does protein digestion start in the human body?

a.the mouth

b. the stomach

c. the small intestine

d.large intestine

Trivia 5

The main function of the large intestine is to:

a.store waste

b.absorb water from digested food

c.digest proteins

d.none of the above