Salivary and Gastric Acid Secretions

Question 1

Although not required, mastication is important for

Answer 1

mechanical breakdown, SA for saliva, easier swallowing

Question 2

Saliva Function

Answer 2

lubrication, dissolving food for taste, heath of gums, R protein for Vit B12 absorption, amylase and ptyalin for carb digestion, HCO3 for H+ neutralization

Question 3

3 salivary glands

Answer 3

parotid, submandibular, and sublingual

Question 4

What types of cells are in salivary glands

Answer 4

acinar and ductal

Question 5

Acinar cell secretions

Answer 5

isotonic electrolyte (Na, Cl, K, HCO3, H2O), active amylase, mucins, tight junctions permeable to water (SECRETION IS ISOTONIC)

Question 6

Ductal cells

Answer 6

reabsorbs Na, HCO3 exchanges for luminal Cl, tight junctions impermeable to water

Question 7

Which salivary gland cells have tight junctions impermeable to water?

Answer 7

ductal

Question 8

Aldosterone effects salivary gland cells by

Answer 8

increasing the absorption of Na by ductal cells, doesn’t effect rate of salivary secretion

Question 9

What regulates rate and volume of salivary secretion?

Answer 9

sympathetic and parasympathetic innervation

Question 10

Final salivary secretion is ________ in comparison to plasma. (hypo- iso- hyper- tonic)

Answer 10

HYPOtonic

Question 11

PNS and SNS activity cause

Answer 11

INCREASED salivation, intitiated by taste, smell, tactile stimuli in mouth

Question 12

PNS increases release of what type of saliva

Answer 12

watery

Question 13

SNS increased release of what type of saliva

Answer 13

proteins and maintains high blood flow to gland by releasing nonadrenergic vasodilators

Question 14

Increased rate of salivation

Answer 14

by PNS during nausea and vomiting

Question 15

Decreased rate of salivation

Answer 15

by inhibition of PNS by fatigue, sleep, fear, dehydration

Question 16

What electrolyte is high at all salivary flow rates

Answer 16

HCO3

Question 17

At the slowest salivary flow rate…

Answer 17

ductal cells reabsorb most Na and exchange most Cl for HCO3, therefore Na and Cl are low, and K is high

Question 18

At the fastest salivary flow rate…

Answer 18

ductal cells reabsorb little Na, therefore highest concentration of Na and lowest K

Question 19

During maximal PNS stimulation would the Na concentration of the saliva be high or low?

Answer 19

HIGH, fast salivation flow rate, low Na reabsorption by ductal cells

Question 20

Gastric secretions have 3 main functions

Answer 20

Digestion, modulate HCl secretion, and protect lining of gut

Question 21

Gastric substances that aid in digestion

Answer 21

HCl (parietal cells), Intrinsic Factor (parietal cells), Gastric lipase (chief cells), and pepsinogen (chief cells)

Question 22

Gastric substances that modulate HCl secretion

Answer 22

Gastrin (G cells), Histamine (ECL cells), Somatostatin (D cells)

Question 23

Gastric substances that protect the stomach lining

Answer 23

Mucus and HCO3 (surface mucous cells and mucous neck cells)

Question 24

Secretory cells present in cardiac glands

Answer 24

surface mucous cells and mucous neck cells - mucus and HCO3

Question 25

Secretory cells present in gastric (oxyntic) glands

Answer 25

surface mucous cells and mucous neck cells - mucus and HCO3, parietal, chief, D cells, ECL

Question 26

Secretory cells present in pyloric glands

Answer 26

surface mucous cells and mucous neck cells - mucus and HCO3, G and D cells

Question 27

HCl secretion by parietal cells - H+ production

Answer 27

Carbonic Anhydrase: CO2 + H2O --> H+ + HCO3

Question 28

HCl secretion by parietal cells - Apical Membrane

Answer 28

H+/K+ ATPase pump: pumps H+ into lumen and K+ into cell

Question 29

HCl secretion by parietal cells - Basolateral membrane

Answer 29

Excess HCO3 is transported across in exchange for Cl-, HCO3 enters blood and CL- diffuses into lumen to generate HCl

Question 30

HCl secretion by parietal cells - H2O

Answer 30

passive diffusion with HCl into lumen

Question 31

Rate limting step of HCl secretion by parietal cells

Answer 31

ATP availability for the proton pump

Question 32

Alkaline tide

Answer 32

refers to the excess HCO3 entering the gastric venous blood, increasing the pH

Question 33

factors that increase HCl secretion act synergistically

Answer 33

Gastrin (Ca2+), Histamine (H2 receptors - cAMP), ACh-muscarinic activation (PNS - Ca2+)

Question 34

Location of receptors for modulation of HCl secretion

Answer 34

basolateral membrane of parietal cell

Question 35

factors that decrease HCl secretion

Answer 35

Somatostatin (D cells - cAMP), Prostaglandin (cAMP), Secretin (S cells) (decrease cAMP)

Question 36

What is more effective in reducing H+ secretion, proton pump inhibitor or H2 receptor antagonist?

Answer 36

Proton pump inhibitor

Question 37

Gastrin Function

Answer 37

increases secretion of HCl, pepsinogen, IF, and Histamine increases phasic contractions, gastric emptying, and colonic motility (mass movements), trophic - stimulates growth of gastric mucosa

Question 38

What factors increase Gastrin secretion

Answer 38

GRP (IPANs), ACh, peptides in gastric lumen, secretin, gastric distention

Question 39

What factors decrease Gastrin secretion

Answer 39

Somatostatin (when pH drops below 3)

Question 40

Histamine Function

Answer 40

Increase HCl and IF, decrease somatostatin

Question 41

What factors increase histamine secretion

Answer 41

gastrin

Question 42

what factor decrease histamine secretion

Answer 42

somatostatin

Question 43

Somatostatins function

Answer 43

inhibits HCl, gastrin, pepsinogen, IF, histamine secretion; reduces local blood flow by constriction of vessels

Question 44

What factors increase somatostatin secretion

Answer 44

Low pH (<3), secretin

Question 45

What factors decrease somatostatin secretion

Answer 45

High pH, ACh, Histamine

Question 46

Why does vagal stimulation inhibit somatostatin?

Answer 46

to maximize HCl secretion for a acidic lumen (optimize enzymes)

Question 47

Vagal Stimulation causes release of ACh from enteric neurons which binds

Answer 47

Muscarinic receptors

Question 48

ACh directly increases secretion of

Answer 48

HCl and gastrin (GRP)

Question 49

ACh directly decreases secretion of

Answer 49

Somatostatin

Question 50

Gastrin directly increased release of

Answer 50

Histamine and HCl

Question 51

Histamine directly activates H2 receptors and increases the secretion of

Answer 51

HCl

Question 52

Histamine directly activates H3 receptors and decreases the secretion of

Answer 52

Somatostatin

Question 53

Other factors that increase PNS activity

Answer 53

distention of stomach, protein products in lumen, pH > 3

Question 54

Other factors that inhibit HCl secretion

Answer 54

duodenal feedback (pH <3, distention of duodenum, high osmolarity in duodenum)

Question 55

Acidic chyme in duodenum causes

Answer 55

Secretin release from S cells, which inhibits HCl secretion and increases somatostatin secretion

Question 56

Hyperosmotic chyme and duodenal distention causes

Answer 56

HCl inhibition via short and long neural reflexes