GI 6

Question 1

Three Major Salivary Glands?

Answer 1

1. Parotid
2. Mandibular
3. Sublingual

Question 2

Secretion from parotid glands?

Answer 2

watery (serous) saliva

Question 3

Secretion from mandibular glands?

Answer 3

mixed serous and mucous

Question 4

Secretion from sublingual glands?

Answer 4

mucous

Question 5

Do the minor glands in the mucosa secrete mucous or serous saliva?

Answer 5

highly mucous

Question 6

3 Functions of Saliva

Answer 6

1. Lubrication
2. Digestion
3. Protection (antibacterial)

Question 7

Is saliva in ruminants acidic or alkaline? Why?

Answer 7

Alkaline - high levels of bicarbonate and phosphate (to neutralize acid generated by fermentation)

Question 8

Is monogastric saliva hypo-, iso-, or hyper- tonic?

Answer 8

hypotonic (very low conc. of all solutes, including sodium)

Question 9

Hypotonic solution

Answer 9

lower concentration of solutes outside than inside the cell

Question 10

Acinar gland

Answer 10

type of salivary gland which secretes mucus, enzymes, water, and electrolytes

Question 11

Duct epithelium

Answer 11

absorbs electrolytes, sodium and chloride; (Secretes bicarbonate and potassium?)

Question 12

Is ALL saliva hypotonic?

Answer 12

NO intitally it is isotonic until duct epithelium does its job

Question 13

Why is water not absorbed by the duct epithelium?

Answer 13

cells are water impermeable

Question 14

Is saliva secretion under any hormonal control?

Answer 14

No, it is exclusively neural (autonomic)

Question 15

Is saliva secretion stimulated by sympathetic or parasympathetic?

Answer 15

both (mainly parasympathetic but still both)

Question 16

What gastric secretions do parietal cells produce?

Answer 16

HCl and intrinsic factor

Question 17

What gastric secretions do chief cells produce?

Answer 17

pepsinogen

Question 18

What gastric secretions do surface mucous cells produce?

Answer 18

mucus and bicarbonate

Question 19

What gastric secretion do enterochromaffin-like cells (ECL) produce?

Answer 19

histamine

Question 20

What gastric secretions come from G cells?

Answer 20

gastrin

Question 21

What gastric secretions come from D cells?

Answer 21

somatostatin

Question 22

What gastric “secretions” (neurotransmitters) come from nerves?

Answer 22

Ach (acetylcholine) and GRP (gastrin-releasing peptide)

Question 23

Intrinsic factor

Answer 23

produced by parietal cells and absorbs Vitamin B12

Question 24

Pepsinogen

Answer 24

inactive precursor to pepsin (enzyme) for protein digestion

Question 25

Histamine

Answer 25

paracrine from ECL cells to promote gastric acid secretion from the parietal cells

Question 26

Somatostatin

Answer 26

paracrine to inhibit gastrin secretion

Question 27

Parietal glands

Answer 27

75% of gastric glands in body of stomach, include parietal cells and chief cells

Question 28

Pyloric glands

Answer 28

in pylorus, made up of mucous cells and G cells

Question 29

Where do G cells release gastrin?

Answer 29

to the bloodstream

Question 30

Alkaline Tide

Answer 30

transient alkalization of the blood

Question 31

4 Steps of HCl Secretion from Parietal Cells

Answer 31

1. Carbon dioxide and water undergo rxns to end upwith H+ and bicarbonate 2. Proton pump on the lumenal/apical aspect will pump H+ out and pull K+ in 3. Cl- follows H+ through channels (diffusion); makes HCl 4. Bicarbonate is pumped out into blood and Cl- pulled in at the basolateral membrane

Question 32

How is alkaline tide reversed?

Answer 32

blood flows into pancreas, pancreas picks up the bicaronate and uses it to neutralize the acid in the intestine

Question 33

Size of effect of gastric acid production on blood pH?

Answer 33

Small and transient

Question 34

Is HCl secretion always stimulated by food?

Answer 34

yes

Question 35

3 Phases for HCl Secretion

Answer 35

1. Cephalic 2. Gastric 3. Intestinal

Question 36

What % of HCl secretion occurs during the cephalic phase?

Answer 36

30%

Question 37

What % of HCl secretion occurs during the gastric phase?

Answer 37

60%

Question 38

Mechanisms of HCl release during Cephalic Phase

Answer 38

CNS can act directly on parietal cells with acetylcholine, or by gastrin-releasing peptde on a G cell to release gastrin which then acts via CCK2 receptor on the parietal cell

Question 39

What is different about the mechanisms of HCl release in the gastric phase?

Answer 39

includes the vagovagal reflex, involves interneurons within the enteric nervous system in addition to the same signals as the cephalic phase

Question 40

Direct Mechanism of Gastrin on HCl Secretion

Answer 40

gastrin binds to CCK2 on parietal cells to stimulate HCl secretion

Question 41

Indirect Mechnism of Gastrin on HCl Secretion

Answer 41

gastrin bind to CCK2 on ECL cells to stimulate histamine release, then histamine can act on parietal cells to stimulate HCl secretion

Question 42

Synergism of HCl Secretion

Answer 42

when gastrin (endocrine), histamine (paracrine), and Ach (NT) all act on parietal cells simultaneously

Question 43

Atropine

Answer 43

anticholinergic effect blocking the ACh binding to the M3 receptor on parietal cells

Question 44

Cimetidine

Answer 44

H2 receptor antagonist; blocks binding of histamine to parietal cells

Question 45

Omeprazole

Answer 45

proton pump inhibitor to block H+ secretion from the parietal cell into the lumen

Question 46

Somatostatin and Prostaglandin effect on HCl secretion

Answer 46

binds to its respective receptor on the parietal cell, decreases cAMP, therefore reducing activity of proton pump putting H+ into the lumen

Question 47

NSAID effect on prostaglandin

Answer 47

inhibits prostaglandin synthesis, therefore removing an inhibitory factor of acid secretion

Question 48

2 Ways Somatostatin Inhibits HCl Secretion in the Stomach

Answer 48

1. Directly on the parietal cells 2. Indirectly by inhibiting gastrin release acts when stomach pH drops below 3.0ish

Question 49

Can neurons in the duodenum inhibit acid secretion by inhibiting gastrin? What about hormones?

Answer 49

no (they directly act on parietal cells) Hormones can do both

Question 50

proenzymes

Answer 50

inactive form of an enzyme that cannot digest protein so the body doesn't digest itself

Question 51

Zymogens

Answer 51

name for the proenzymes used in digestion

Question 52

Peptic Ulcer Disease Causes

Answer 52

mucosal loss on the protective layer, excess H+ and pepsin secretion; due to imbalance of protectiive and damaging factors in gastroduodenal mucosa