GI 2: Salivary & Gastric Secretions

Question 1

what are the 3 pairs of salivary glands?

Answer 1

1. parotid
2. submandibular
3. sublingual

Question 2

what are the 4 things saliva contains?

Answer 2

1. mucous
2. bicarb and phosphate ions
3. salivary amylase ptyalin
4. lysozyme

Question 3

what is the function of mucous in the saliva?

Answer 3

lubrication

Question 4

what is the function of bicarb and PO4 in the saliva

Answer 4

pH neutralization

Question 5

what is the function of salivary amylase ptyalin?

Answer 5

10% of carbohydrate digestion

Question 6

what is the function of lysozyme in saliva?

Answer 6

anti-bacterial

Question 7

~___L of saliva is secreted daily

Answer 7

1

Question 8

salivary secretions are stimulated by ____ signals in response to taste, touch, sight, and smell

Answer 8

parasympathetic

Question 9

lingual lyase breaks down ___

Answer 9

lipids

Question 10

the pH is ~___ when it reaches the esophagus

Answer 10

6.5

Question 11

the ____ layer of the stomach contains gastric pits

Answer 11

mucosa

Question 12

function of surface mucous cells

Answer 12

secrete mucous to line and protect

Question 13

function of the mucous neck cells

Answer 13

secrete HCO3 (act as buffer)

Question 14

what are the 4 different types of cells in the gastric pits?

Answer 14

1. mucous cells
2. parietal cells
3. chief cells
4. endocrine cells

Question 15

what are the 3 types of endocrine cells and the tings they secrete

Answer 15

1. G cells = gastrin
2. ECL cells = histamine
3. D cells = somatostatin

Question 16

what is the function of the mucous cells of the gastric pits?

Answer 16

secrete alkaline mucous to protect stomach from its low pH

Question 17

what is the function of the parietal cells?

Answer 17

secrete HCL and intrinsic factor

Question 18

what is intrinsic factor?

Answer 18

protein needed for absorption of B12

Question 19

what is the function of the chief cells?

Answer 19

secrete pepsinogen

Question 20

what does the suffix “ogen” mean?

Answer 20

secreted in inactive form

Question 21

once activated, what is the function of pepsinogen?

Answer 21

breakdown peptides

Question 22

what is responsible for the stomach’s low pH?

Answer 22

HCL secreted by parietal cells

Question 23

what are the 5 functions of HCL secretion in the stomach?

Answer 23

1. antibacterial
2. denatures proteins
3. transforma pepsinogen to pepsin
4. inactivates salivary amylase
5. activates lingual lipase

Question 24

carbonic anhydrase converts ___ and __ into ___

Answer 24

CO2 and H20 into H2CO3

Question 25

H+ is ____ (active/passive) transported in the stomach lumen via_____

Answer 25

actively; H+/K ATPase

Question 26

HCO3 is ____ (active/passive) transported in the intestinal fluid via ____

Answer 26

passive; HCO3/Cl exchanger

Question 27

CL is transported in the stomach lumen via ___

Answer 27

uniport channel

Question 28

acid secretion in the stomach requires translocation of ___ from the cytoplasm to the apical membrane of the cell

Answer 28

H/atpases

Question 29

translocation of the H/ATPases is activated by what 3 things?

Answer 29

1. gastrin 2. histamine 3. ACh (PNS)

Question 30

explain the potentiation of acid secretion involving histamine

Answer 30

histamine increases the cell's sensitivity to gastrin and Ach, so the response is greater than the sum of the 3 individual effects

Question 31

where are H/atpases typically found before their translocation?

Answer 31

vessicles

Question 32

what is the role of somatostatin wrt H/ATPase?

Answer 32

reduces translocation to membrane

Question 33

give 2 examples of drugs used to decrease gastric acid secretion

Answer 33

1. proton-pump inhibitor (omeprazole) | 2. histamine H2 receptor antagonists

Question 34

explain how intrinsic factor helps with absorption of B12

Answer 34

intrinsic factor binds to b12 forming an indigestible complex that is then absorbed by the ileum by endocytosis

Question 35

B12 is critical due to its role in ___ synthese

Answer 35

red blood cell (DNA synthesis)

Question 36

list 4 posible causes of B12 deficiencies

Answer 36

1. dysfunction of gastric parietal cells (pernicious anemia) 2. resection (surgical removal) of terminal ileum 3. catabolism of the vitamin by bacteria in the small intestine 4. pancreatic insufficiency

Question 37

adequate absorption of B12 from the diet depends on what 5 things?

Answer 37

1. amount of dietary intake 2. HCL and pepsin in stomach to free B12 from binding to dietary proteins 3. pancreatic processes to free B12 from binding to R factors 4. secretion of intrinsic factor by the gastric parietal cells 5. intact ileum with functional receptors

Question 38

B12 must be bound to ___ to be protected

Answer 38

protein