Digestion 2

Question 1

what hydrolyses proteins?

Answer 1

enzymes called peptidases

Question 2

what type of peptidase breaks down large polypeptides into smaller oligopeptides?

Answer 2

endopeptidase

Question 3

what type of peptidase breaks down oligopeptides into di- and tripeptides and amino acids?

Answer 3

exopeptidases

Question 4

what is an enterocyte?

Answer 4

cell of the intestinal lining

Question 5

in what organ does protein digestion begin?

Answer 5

stomach

Question 6

the stomach secretes ? which causes protein ?

Answer 6

HCl
denaturation

Question 7

? cells of the gastric mucosa secrete ? - the inactive precursor of pepsin

Answer 7

chief
pepsinogen

Question 8

pepsinogen is initially activated by ? to form activated pepsin

Answer 8

low pH

Question 9

what does pepsin do?

Answer 9

digests the target protein into large peptide fragments and amino acids

Question 10

the digestion of the target protein by pepsin stimulates ? to be released in the duodenum

Answer 10

cholecystokinin (CCK)

Question 11

acidity of the stomach contents entering the duodenum stimulates the secretion of what peptide hormone?

Answer 11

secretin

Question 12

secretin stimulate the secretion of ? rich fluid to ? and ? the acid in the duodenum and also stimulates secretion of ? ? and ? intestinal juice

Answer 12

bicarbonate
neutralise
dilute
alkaline bile
alkaline

Question 13

cholecystokinin cck stimulates the release of ?
by the ?

Answer 13

the main digestive enzymes
pancreas

Question 14

cholecystokinin causes contraction of the ? and relaxation of the ? promoting entry of ? and ? into the ?

Answer 14

gall bladder
sphincter of Oddi
bile
pancreatic juices
duodenum

Question 15

pancreatic enzymes that are released as inactive precursors are called?

Answer 15

zymogens

Question 16

what converts trypsinogen to trypsin?

Answer 16

duodenal enteropeptidases

Question 17

what controls the activity of trypsin?

Answer 17

an inhibitory peptide

Question 18

small intestine peptidases at the brush border of enterocytes are membrane bound ?, ? and ?

Answer 18

endopeptidases
dipeptidases
aminopeptidases

Question 19

the final digestion of peptides occur ? the enterocytes forming ? by ?

Answer 19

inside
amino acids
cytosolic peptidases

Question 20

how are amino acids transported into the enterocyte and out into the blood

Answer 20

active mechanisms such as Na+ dependant co-porters

Passive diffusion

Question 21

di and tri-peptides are transported across the brush border of enterocytes by?

Answer 21

H+ dependant co-porter
creating an electrochemical gradient

Question 22

amino acids leave the enterocyte into the capillary by what transport mechanism?

Answer 22

facilitated diffusion - Na+ independent

Question 23

most water soluble vitamins are absorbed by?

Answer 23

passive diffusion

Question 24

fat soluble vitamins are carried in the ? and absorbed by the ?

Answer 24

micelles
enterocytes

Question 25

water soluble vitamins are?

Answer 25

b vitamins
c

Question 26

fat soluble vitamins are?

Answer 26

A
D
E
K

Question 27

the 4 metabolically important forms of B12 are called?
(not essential to know)

Answer 27

cobalamins

Question 28

cobalamins are generally bound to ? and are required for what?
(not essential to know)

Answer 28

proteins
red blood cell development

Question 29

Cobalamins are generally bound to 1. They are released from this complex by 2. They are then bound to a glycoprotein called 3. These complexes are degraded by 4 In the duodenum. The free cobalamin then binds to a glycoprotein called 5. The complex is absorbed into the ileum by 6 Which is 7 Dependant. Within the cell the complex dissociates and free B12 binds to 8 Which leaves the cell, enters the 9 And is taken up by the 10 Using receptor mediated 11 For storage.
(not essential to know)

Answer 29

1 proteins
2 pepsin
3 haptocorrin
4 trypsin -> pancreatic proteinases
5 in5trinsic factor (IF)
6 active transport
7 Ca+
8 transcobalamin
9 portal vein
10 liver
11 endocytosis

Question 30

vitamin D plays a major role in the regulation of ? 2

Answer 30

calcium and phosphorus metabolism

Question 31

what are the sources of vitamin D? 2

Answer 31

sun by the action of UV radiation
diet associated with fats

Question 32

vitamin D deficiency leads to ? 3

Answer 32

calcium malabsorption
rickets in children
osteomalacia in adults

Question 33

how is the active molecule of vitamin D formed?

Answer 33

hydroxylation in the liver and kidney

Question 34

where is calcium absorbed?

Answer 34

proximal small intestine

Question 35

Calcium Regulation
Decrease in ionised calcium in plasma stimulates the release of 1. This promotes Ca2+ reabsorption, from kidney and bone, and increase gut absorption via increased production of 2.

Answer 35

1. parathyroid hormone
2. activated vitamin D3

Question 36

Increase in ionised calcium in plasma stimulates release of ? which inhibits resorption (lowers serum Ca2+)

Answer 36

calcitonin

Question 37

the majority of the bodies iron is found in?

Answer 37

haemoglobin and myoglobin

Question 38

Deitary iron is in the ferric form 1. It is reduced in the GI tract to the ferrous form 2. It is transported into the enterocytes by 3. When erythrocytes (RBC) are are iron rich iron is stored in the enterocytes incorporated into the protein 4. If not iron is transported across the membrane into plasma. Fe2+ is oxidised to Fe3+ by 5. Fe3+ is then bound to 6 in the plasma. Transferrin is taken up in the bone marrow by 7. The iron is then released, reduced to Fe2+ and transported to the 8 for incorporation into 9.
(really not essential to know)

Answer 38

1 Fe3+
2 Fe2+
3 a divalent metal transporter
4 ferritin
5 ferroxidase
6 transferrin
7 erythrocyte precursor cells
8 mitochondria
9 HEME