GI System - Lecture 3

Question 1

what is the 3 main cells in the gastric gland

Answer 1

mucous neck cells, parietal cells and chief cells

Question 2

what pump do drugs work on to control the acidity inside the stomach

Answer 2

potassium proton pump

Question 3

what inhibitor is used for the production of HCl in the stomach

Answer 3

prostaglandins

Question 4

what 3 mechanisms control gastric acid secretion

Answer 4

neurocrine (vagal/local reflexes), endocrine (gastrin) and paracrine (histamine)

Question 5

what are local reflexes

Answer 5

they are related to ENS (enteric NS)

Question 6

what are the 3 phases to stimulating gastric acid

Answer 6

cephalic phase, gastric phase and intestinal phase

Question 7

what do G cells release

Answer 7

gastrin

Question 8

what does ACh, gastrin and histamine activate in the cephalic phase

Answer 8

parietal cells

Question 9

what is the difference in cephalic phase and gastric phase

Answer 9

the activation of the enteric reflexes are turned on in the gastric phase

Question 10

what happens when there is peptides in the lumen of the stomach

Answer 10

activates G cells and secretes gastrin

Question 11

what happens when there is acid in the duodenum

Answer 11

activation of the splanchnic nerve and the release of secretin

Question 12

what does the release of secretin and activation of the splanchnic nerve have on gastrin

Answer 12

decreases the secretion of gastrin, leading to decreased stimulation of the parietal cells

Question 13

what type of effect does the splanchnic nerve have on the release of HCl

Answer 13

inhibitory effect

Question 14

what are enterogastrones

Answer 14

hormones release from gland cells in duodenal mucosa

Question 15

what 3 hormones are released from gland cells in the duodenal mucosa

Answer 15

secretin, cholecystokinin (CCK) and GIP (gastric inhibitory polypeptide)

Question 16

how do enterogastrones get activated

Answer 16

release in response to acid, hypertonic solutions, fatty acids or monoglycerides

Question 17

what is the last part of the small intestine

Answer 17

ileum

Question 18

if a patient has problems in their parietal cells and they cannot produce intrinsic factor, what would there diagnosis be called

Answer 18

pernicious anaemia

Question 19

what does pernicious mean

Answer 19

gradual

Question 20

how does pepsinogen get activated

Answer 20

when it is in acidic pH

Question 21

what is the purpose of the pepsinogen

Answer 21

turns into pepsin and then pepsin will hydrolyses (degrade) proteins

Question 22

how does pepsin get inactivated

Answer 22

when pH goes up to neutral

Question 23

what cells secrete gastric mucus

Answer 23

epithelial cells and mucus neck cells

Question 24

what is the role of gastric mucus

Answer 24

protect the stomach wall from HCl and pepsins

Question 25

what is the pH of the thick mucus layer in the stomach

Answer 25

neutral

Question 26

what is the bolus called as it is digested in the stomach

Answer 26

chyme

Question 27

what substance is used to neutralise acids in the duodenum

Answer 27

HCO3 (bicarbonate)

Question 28

what gland in the duodenum secretes bicarbonate

Answer 28

Brunner's Gland

Question 29

how is the secretion of bicarbonate in the duodenum controlled

Answer 29

long (vagal) and short (ENS) reflexes and release of secretin from S cells

Question 30

what two portions is the pancreas divided into

Answer 30

pancreatic islets (endocrine) and acinar cells (exocrine)

Question 31

what does it mean if the gland is endocrine

Answer 31

the gland will secrete hormone or chemicals directly into the blood

Question 32

what do pancreatic islets secrete

Answer 32

insulin, glucagon and somatostatin

Question 33

what does glucagon control

Answer 33

blood glucose

Question 34

what does somatostatin control

Answer 34

secretion of insulin and glucagon

Question 35

what does it mean if the gland is exocrine

Answer 35

if the gland secretes the hormones/chemical outside the body

Question 36

how are different lobules connected together

Answer 36

by intercalated ducts

Question 37

what cells secrete digestive enzymes

Answer 37

acinar cells

Question 38

why are stored zymogens inactive

Answer 38

to prevent the autodigestion of pancreas

Question 39

how does trypsinogen get activated

Answer 39

when it is bound to the brush border of the duodenum enterocytes

Question 40

what does trypsinogen turn into

Answer 40

trypsin

Question 41

what is the function of trypsinogen

Answer 41

converts all other zymogens to active form

Question 42

what are the different categories of the pancreatic enzymes

Answer 42

proteases, nucleases, elastases, phospholipases, lipases and alpha-Amylase

Question 43

what is the function of protases

Answer 43

cleave peptide bonds (degrade them)

Question 44

what is the function of nucleases

Answer 44

hydrolyses (degrade) DNA/RNA

Question 45

what is the function of elastases

Answer 45

causes collagen digestion

Question 46

what is the function phospholipases

Answer 46

turns phospholipids to fatty acids

Question 47

what is the function of lipases

Answer 47

turns triglycerides to fatty acids and glycerol

Question 48

what is the function of a-amylase

Answer 48

turns starch into maltose and glucose

Question 49

how are zymogens stimulated

Answer 49

by cholecystokinin (CCK)

Question 50

when is CCK released

Answer 50

in response to fat/amino acids in the duodenum

Question 51

what type of cells are activated during the cephalic phase

Answer 51

parietal cells