What the organs do

Question 1

Mouth

Answer 1

Has first role in digestive system

chews and breaks down food both chemically and physically

chemically with its saliva that has amylase to break down starch

physically with teeth

pushes it into the esophagus

Question 2

Esophagus

Answer 2

Moves food from mouth to stomach by muscular peristalsis which is the rhythmic wave like contractions of the muscles in the gi tract

aided by gravity

Question 3

Stomach

Answer 3

j shaped

has a gastreoesophageal sphincter where the esophagus meets the stomach

4 layers of the stomach

1. mucosa
   - secretes gastric juice
   - epithlial cells divide
2. submucosa
   - connective tissue, blood vessels and nerves
3. muscularis
   - layers of smooth muscle
   - contract, churn, mix the food to make chyme
4. serosa
   - jold stomach in place
   - secretes lubricating fluid to eliminate friction

Question 4

Large intestine

Answer 4

1.5 m length and 7.6 in diameter

appendix

colon - acending, transverse, descending and sigmoid

the colon absorbs water and vitamins and home to bacteria

rectum - last 20 cm
holds waste
4-72 hrs

egestion
- helped by fibre
too much water - constipated
too little water - diarrhea

Question 5

Small intestine

Answer 5

consists of the duodenum, jejunum and ileum

enzymes break down remaining components of food in the duodenum

allows molecules to be absorbed so body receives nutrients

Question 6

Why is the small intestine surface area important

Answer 6

small in diameter but 7m long

it increases surface area as food goes down allowing for more nutrients to be absorbed

villi increases surface area a lot make it very efficient

perfectly designed to absorb the greatest amount of nutrients possible

Question 7

Pancreas

Answer 7

secretes pancreatic fluid

contains enzymes to digest carbs, lipids and proteins

trypsin breaks proteins
lipases breaks fats

Question 8

Liver

Answer 8

largest internal organ

produces bile

bile emulsifies fat and breaks them into micelles

micelles are more effective for lipases (enzyme that breaks down trigycerides) because of a greater surface area

Question 9

Sphincter

Answer 9

circular muscle that contract to close an opening in the body (more than 50 in human body)

Question 10

Gall bladder

Answer 10

stores bile

when fats and lipids are in the duodenum its contracted

contractions causes bile to be squeezed into the bile duct