VI-Secretions

Question 1

serous secretions have

Answer 1

watery product with enzymes like alpha-amylase

Question 2

mucus secretions have

Answer 2

water + electrolytes + phospholipids + mucin

Question 3

tonicity of fluid

Answer 3

1. initial fluid into lumen is isotonic
2. gets increasingly hypotonic

Question 4

how hypotonic solution made

Answer 4

NaCl reabsorped + KHCO3 secreted so the solution secreted is
-low in NaCl and rich in bicarb

Question 5

why water not reabsorbed

Answer 5

ductal cells express tight junction proteins so water stays in lumen

Question 6

alpha-amylase function

Answer 6

starch digestion

Question 7

secretions that maintain oral hygiene

Answer 7

1. immunoglobulin A IgA
2. lysozyme
3. lactoferrin

thru antimicrobial properties

Question 8

mucin function

Answer 8

lubrication and protection of oral mucosa

Question 9

electrolytes in saliva function

Answer 9

aka H2O, Na, K, Cl

lubrication for mastication and swallowing, taste/smell, speech

Question 10

bicarb function

Answer 10

neutralize gastric acid reflux

Question 11

surface mucous cells/neck cells function

Answer 11

1. secrete mucus and bicarb
2. for gastroprotection

Question 12

parietal cell function

Answer 12

1. secrete HCl aka acid for protein digestion, sterilization, nutrient absorption
2. secrete intrinsic factor for vit B12 absorption

@ body stomach

Question 13

chief cells function

Answer 13

1. secrete pepsinogen
2. for protein digestion

@ body stomach

Question 14

ECL cell function

Answer 14

1. secrete histamine to promote HCl secretion

‘entero-chromaffin like’

Question 15

neurons function in regulation

Answer 15

1. secrete Ach
2. promote mucus, bicarb, and HCl secretion

Question 16

G cell function

Answer 16

1. gastrin @antrum
2. promote HCl secretion

Question 17

D cell function

Answer 17

1. secrete somatostatin
2. to suppress HCl secretion

Question 18

direct regulators of parietal cell

Answer 18

1. histamine (paracrine) - H2R > cAMP
2. gastrin (endocrine) - CCK2 > Ca
3. Ach (neuronal)- M3 > Ca

Question 19

indirect regulation parietal cells

Answer 19

1. somatostatin (paracrine) - D cells, neighboring G cells
2. gastrin- ECL cells
3. Ach - GPR on G cells

Question 20

vitamin B12 degradation

Answer 20

1. B12 released during gastric disruption
2. binds haptocorrin until degraded in duodenum
3. IF binds B12 to form complex until absorbed in ileum

Question 21

activation of pepsinogen

Answer 21

1. secreted from chief cell by Ach stim
2. requires HCl
3. pH of 1.8 - 3.5
4. can activate other pepsin molecules

Question 22

how mucus protects gastric mucosa

Answer 22

1. create physical barrier
2. inc pH at mucosal surface/buffered environment
3. preventing activation of pepsinogen since pH too high

Question 23

2 main secretion stimulants

Answer 23

1. Ach
2. prostaglandins

Question 24

function of prostaglandins

Answer 24

1. mucus and bicarb secretion
2. suppression of HCl secretion thru inhibiting histamine pathway
3. inc gastric blood flow

Question 25

primary causes of acid peptic disease

Answer 25

1. H. pylori infection
2. NSAIDs

Question 26

other causes of acid peptic disease

Answer 26

1. inc number parietal cells
2. high serum gastrin levels
3. loss acid mediated neg feedback on gastrin
4. rapid gastric emptying
5. cigarette smoking
6. alcohol use
7. dec mucosal bicarb secretin
8. GERD

Question 27

how H. pylori is toxic

Answer 27

1. has urease to buffer HCl
   -gets converted to ammonia and carbon dioxide > ammonia buffers hydrogen ions, carbon dioxide converted to bicarb by carbonic anhydrase
   -ammonia is toxic to epithelium and mucosal cells
2. virulence factors for adhesion, immune resp, and breakdown of mucus gel layer

Question 28

how NSAIDs cause gastritis

Answer 28

inhibit COX1/2 so prostaglandins dec
-loss of secretion inhibition