Lecture 33

Question 1

function of oral phase

Answer 1

lubricate and moisten food
solubilization of material for taste

Question 2

How does oral cavity break down food

Answer 2

everything mechanically broken down

chemically
carbs- salivary amylase
fats- lingual lipase
neutralizing germs by enzymes

Question 3

How does swallowing occur?

Answer 3

tongue pushes down bolus which lead the epiglottis to cover the trachea and the stretch receptors allow the upper esophageal sprinter to open. the esophagus uses peristalsis to push down the food

Question 4

functions of the stomach (gastric phase)

Answer 4

chemically and mechanically digest, protect and store food

Question 5

Why does the stomach have an mucus bicarbonate layer

Answer 5

the layer is to protect the stomach lining from the acidity of the HCl. if it is breached one could get an stomach ulcer

Question 6

What gets digested in the stomach?

Answer 6

fats and proteins

Question 7

How does gastric phase break down proteins?

Answer 7

1) the HCl denatures the proteins so they unfold
2) Pepsinogen is turned into pepsin by the HCl to cleave the bonds into amnio acids

Question 8

where does HCl come from?

Answer 8

the parietal cells in gatric pit

Question 9

where does the mucus and bicarbonate come from

Answer 9

mucus(globlet) and neck cells

Question 10

How does gastric phase break down fats?

Answer 10

1) Course emulsification of fats by the motility
2) gastric lipase to break down into free fatty acids and monoglycerides

Question 11

what are the enzymes used in the stomach and where do they come from?

Answer 11

pepsin and gastric lipase comes form the chief cells

Question 12

function of the small intestine

Answer 12

digestion, absorption, and secretion.
regulation of gastric emptying

Question 13

What is in the walls of the small intestines?

Answer 13

-enterocyctes: has microvilli to create a brush border where digestive enzymes can break down the nutrients and absorptions
- globet cells: mucus for lubrications
- lacteals: absorb into fats lympathtic
- capillaries: absorb nutrients

Question 14

what is the exocrine pancreas

Answer 14

• acinar cells to secrete the digestive enzymes like proteases, amylases and lipases
• duct cells to transport bicarbonate to neutralize the acids chyme from stomach not the intestine.

Question 15

how do the pancreas secretions get into the small intestine?

Answer 15

it gets in by the pancreas duct that does through the splinter of oddi to the duodenum

Question 16

what is bile and where is it from

Answer 16

bile is NOT an enzyme
it is a solution of bile salts and cholesterol to to help emulsify and absorb fats
it is made in the liver but concerted in the gallbladder

Question 17

how does the small intestine digest carbs?

Answer 17

pancreatic amylase and the brush border enzymes in the duodenum and jejumn

Question 18

what is the 3 types of monosaccharides?

Answer 18

glucose, fructose and galactose

Question 19

where are the disaccharides converted into monosaccharides and what brush border enzymes break them down?

Answer 19

the small intestine
maltose - maltose (2 glucoses)
sucrase- sucrose (1 fructose, 1 glucose)
lactase - lactose (1 glucose, 1 galactose)

Question 20

How does the small intestine digest proteins

Answer 20

mechanically by segmental contractions
chemically by peptidases

Question 21

example of peptidases

Answer 21

pancreatic enzymes like chymotrypsin
endopeptidases - cut in middle
exopepetidases- cut at the ends

Question 22

how does the small intestines digest fat

Answer 22

fine emulsification by bile salts and pancreatic lipase

Question 23

how does bile help digest fat

Answer 23

they are amprotic so the hydrophobic side sticks to the fat and the hydrophilic side goes to the water

it creates smaller pieces called micelles and are brought towards the enterocytes

Question 24

how is fat absorbed (details)

Answer 24

1) bile salts surround the large fat droplets
2) pancreas lipase and colipase breaks them down into monoglycerides and free fatty acids turning them into micelles
3) the micelles go to the cells
- cholesterol transports through cells
- fatty acids and monoglycerides diffuse in
4) the cholesterol combines with protein and the fatty acids to turn chylomicrons in the smooth ER & Golgi apparatus
5) they are removed by the lacteals

Question 25

how much fluid does the large absorb?

Answer 25

aborbs most of the 1.5L a day pf fluid that enters

Question 26

parts of the large intestine

Answer 26

• ascending, transverse descending, rectum

Question 27

defection

Answer 27

contains leftover fibre, dead bacteria, water, metabolites and epithelial

Question 28

Colon microflora

Answer 28

in colon there are bacteria that
- produce 50% of the vitamin k needed
- digest cellulose
- kill bacteria