Digestion

Question 1

what is digestion?

Answer 1

hydrolysis of large biological molecules into smaller double molecules

Question 2

What is the definition of absorption?

Answer 2

is the process of absorbing the products of digestion into the epithelial cells of the small intestine and into the blood

Question 3

What is the process of the oesophagus squeezing food down to the stomach called?

Answer 3

peristalsis

Question 4

what does the liver produce?

Answer 4

bile

Question 5

what does bile contain?

Answer 5

bile salts which emulsify lipids, it doesn’t contain digestive enzymes

Question 6

the function of the gall bladder?

Answer 6

stores bile, to be released when food leaves the stomach

Question 7

what does the pancreas release?

Answer 7

pancreatic juice, into the small intestine the food leaves the stomach

Question 8

What does pancreatic juice contain?

Answer 8

alkaline salts which neutralise stomach acid and digestive enzymes: pancreatic amylase, lipase, sucrase, lactase and peptidases

Question 9

what is physical digestion?in mouth

Answer 9

food is chewed to break it up, increasing surface area and mix it with Slava from salivary glands

Question 10

what is chemical digestion?in mouth

Answer 10

salvia contains the enzyme salivary amylase

Question 11

what is physical digestion? in stomach

Answer 11

food is churned with gastric juice for up to 4 hours

Question 12

what is chemical digestion?

Answer 12

gastric juice contains hydroclauric acid and peptidases enzymes

Question 13

what does the ileum produce?

Answer 13

intestinal juices containing various digestive enzymes

Question 14

function of the ileum?

Answer 14

main site of absorption. of nutrients into the blood stream

Question 15

function of large intestine?

Answer 15

absorption of excess water from the indigestible remains of food

Question 16

function of rectum

Answer 16

stores and hardens faeces

Question 17

what reactions occur in digestion?

Answer 17

hydrolysis

Question 18

digestion of starch to glucose

Answer 18

slaviary amylase is released into the mouth and hydrolyses starch to maltose. in the small intestine any undigested starch is hydrolysed by pancreatic amylase .

Question 19

describe the different ways in which glucose/amino acid is absorbed into the intestinal epithelial cells?

Answer 19

sodium ions leave epithelial cells and enter blood by active transport/carrier protein using ATP. the sodium concentration in the the cell is then lower then the lumen of the intestine. sodium ions then enter by facilitated diffusion. glucose then absorbed with the sodium ions against there concentration gradient (co transport)

Question 20

Lactase

Answer 20

hydrolyses lactose into glucose and galactose

Question 21

sucrase

Answer 21

hydrolyses sucrose to glucose and fructose

Question 22

Maltase

Answer 22

hydrolyses maltose into glucose nd glucose

Question 23

why are lipids difficult to digest?

Answer 23

they are not double in water

Question 24

what is produced by the body to allow lipids to be digested?

Answer 24

bule salts
emulsifies fats which increase surface area of the lipid

Question 25

lipase

Answer 25

hydrolyses triglycerides into fatty acids and monoglycerides

Question 26

where is lipase produced?

Answer 26

pancreas

Question 27

where is lipase released to?

Answer 27

small intestine

Question 28

when lipase hydrolyses lipids associated with bile salts this forms

Answer 28

micelles, fatty acids and bile salts

Question 29

what are micelles made up of?

Answer 29

bile salts, monoglyceride and fatty acid

Question 30

what is the function of a micelle?

Answer 30

it makes monoglycerides/fatty acids more double in water
it then enables them to be transported to the cell membrane of the epithelial cells of the small intestine, increasing concentration gradient

Question 31

what molecules diffuse through the cell surface membrane?

Answer 31

monoglycerides and fatty acids cross the membrane through simple diffusion as they are lipid souble

Question 32

how are lipids absorbed?

Answer 32

-micelles bring fatty acids and monoglycerides to the cell surface membrane of the intestinal epithelial cells
-cross the membrane through simple diffusion as they are lipid souble
-the monoglycerides and are used to synthesise triglycerides in the smooth ER
-the triglycerides are then modified, resulting in chylomicrons formed by the Golgi apparatus
-the chylomicron are released by exocytosis into tissue fluid
-they move into lacteal
-the lymphatic system eventually moves lymph into the blood so chycomicrons can enter

Question 33

structure of glycomicron

Answer 33

phospholipid, triglyceride, protein and cholesterol

Question 34

function of chlycomicron

Answer 34

transport triglycerides in the blood to peripheral tissues and liver

Question 35

digestion of proteins to amino acids

Answer 35

the stomach, pepsin is produced and released by gastric cells, this hydrolyses peptide bonds in the middle of polypeptide producing shorter polypeptide chains.
the small intestine- endopeptidases, exopeptidase and dipeptidiades

Question 36

what enzymes break down proteins?

Answer 36

peptidase enzymes

Question 37

where are endopeptidases produced?

Answer 37

pancreas or stomach

Question 38

where’s endopeptidases site of action

Answer 38

stomach and small intestine

Question 39

function of endopeptidases?

Answer 39

hydrolyses peptide bonds in middle of peptide producing shorter peptide chains

Question 40

where are exopeptidase produced?

Answer 40

pancreas

Question 41

where are exopeptidase released?

Answer 41

small intestine

Question 42

function of exopeptidase?

Answer 42

hydrolyses peptide bonds at ends of peptide chains releasing dipeptides/amino acids

Question 43

where are dipeptidases produced?

Answer 43

small instestine

Question 44

where are dipeptidases released?

Answer 44

small insteitine

Question 45

function of dipeptidases?

Answer 45

hydrolyses dipeptides into amino acids

Question 46

how are the villi adapted for absorption?

Answer 46

-large surface area (due to villi and microvilli)
-very thin walls (short diffusion path for absorption)
-Good blood supply (short diffusion path)
-able to move (propel food along)
-Lacteal (absorb lipids)