Lecture 15 - OTC Digestion

Question 1

there are a number of common maladies that can afflict the GI tract, including:

Answer 1

• peptic ulcers
• gastroesophageal reflux disease (GERD)
• nausea and vomiting
• GI motility prblems (constipation and diarrhea)

Question 2

a group of disorders involving either excessive acid secretion or erosion of the mucosal lining of the GI tract (particularly the stomach)

Answer 2

acid-peptic diseases

Question 3

the stomach is divided into the:

Answer 3

antrum (bottom) and fundus (top)

Question 4

cells in the fundus of the stomach responsible for acid secretion (H+ ions)

Answer 4

parietal cells

Question 5

moves acid from the parietal cell into the gastric lumen

Answer 5

the H+/K+ ATPase proton pump

Question 6

cells in the antrum that respond to intraluminal dietary peptides to release gastrin

Answer 6

G-cells

Question 7

gastrin binds to:

Answer 7

cholecystokinin (CCK) receptors on parietal cells

Question 8

gastrin stimulates ______ to release ______ which binds to ______ on parietal cells

Answer 8

enterochromaffin cells (H cells), histamine, histamine (H2) receptors

Question 9

the vagus nerve stimulates postganglionic neurons of the enteric nervous system to release ______, which binds to ______ on parietal cells

Answer 9

acetylcholine, muscarinic receptors (M3)

Question 10

cells which release somatostatin and inhibit gastrin release from G cells

Answer 10

D cells

Question 11

what causes D cells to release somatostatin?

Answer 11

an increase in intraluminal acid

Question 12

what effect does excess acid production have on the stomach?

Answer 12

it erodes the mucosal barrier

Question 13

loss of sphincter integrity can lead to:

Answer 13

acid in the esophagus

Question 14

most OTC treatment for peptic ulcer disease are focused on:

Answer 14

controlling acid production in the stomach (antacids and proton pump inhibitors)

Question 15

weak bases that neutralize stomach acid by reacting with protons in the lumen of the gut

Answer 15

antacids

Question 16

popular antacids include:

Answer 16

magnesium hydroxide (Mg[OH]2) and aluminium hydroxide (Al[OH]3)

Question 17

when used regularly, in the large doses required to raise stomach pH, antacids reduce the:

Answer 17

recurrence rate of peptic ulcers

Question 18

magnesium hydroxide has a strong:

Answer 18

laxative effect

Question 19

aluminium hydroxide has a:

Answer 19

constipating action

Question 20

lipophilic weak bases that diffuse into the parietal cell and inactivate the H+/K+ ATPase transporter

Answer 20

proton pump inhibitors (ex: Omeprazole)

Question 21

prolonged use of proton pump inhibitors can lead to:

Answer 21

hypergastrinemia

Question 22

proton pump inhibitors will decrease the bioavailability of:

Answer 22

vitamin B12 and certain drugs that require acidity for their absorption

Question 23

nausea and vomiting is an important defence against:

Answer 23

food poisoning

Question 24

can help when dealing with nausea and vomiting caused by motion sickness caused by other conditions

Answer 24

OTC anti-emetics

Question 25

the active ingredient in PeptoBismol

Answer 25

bismuth subsalicylate

Question 26

bismuth subsalicylate hydrolyzes in the gut to:

Answer 26

bismuth oxychloride and salicylic acid

Question 27

salicylic acid is absorbed in the gut and:

Answer 27

inhibits prostaglandin synthesis (anti-inflammatory properties)

Question 28

bismuth salts are not absorbed from the gut, but have:

Answer 28

bactericidal effects

Question 29

dimenhydrinate (gravol) is a theoclate salt composed of:

Answer 29

diphenhydramine and 8-chlorotheophylline

Question 30

dimenhydrinate acts as a ______ at the ______ receptor

Answer 30

competitive antagonist/inverse agonist, H1

Question 31

what is the effect of 8-chlorotheophylline?

Answer 31

reduces potency of dimenhydramine

Question 32

what is the effect of dimenhydrinate?

Answer 32

blocks histamine activity in the vestibular system, but less sedation than diphenhydramine (less potent)

Question 33

GI motility is controlled by:

Answer 33

intrinsic neural plexuses (enteric nervous system)

Question 34

removing extrinsic autonomic control of the GI tract results in:

Answer 34

disorganized gastric activity (nausea and vomiting)

Question 35

the enteric nervous system is also known as the:

Answer 35

"second brain"

Question 36

enteric neurons are organized into a:

Answer 36

nerve plexus

Question 37

provides motor innervation to the muscular layer of the gut (mediates peristalsis)

Answer 37

myenteric plexus

Question 38

provides secretomotor (inducing a gland to secrete a substance) innervation to the gut mucosa

Answer 38

submucosal plexus

Question 39

the neurons of the myenteric plexus and submucosal plexus are predominantly:

Answer 39

cholinergic

Question 40

all preganglionic neurons in the autonomic nervous system are:

Answer 40

cholinergic

Question 41

postganglionic parasympathetic neurons are:

Answer 41

cholinergic

Question 42

postganglionic sympathetic neurons are:

Answer 42

adrenergic

Question 43

preganglionic parasympathetic neurons release acetylcholine onto postganglionic neurons within:

Answer 43

myenteric neurons within the stomach and upper intestine

Question 44

binds to muscarinic receptors (M2) on GI smooth muscle leading to contraction

Answer 44

acetylcholine

Question 45

acetylcholine stimulates the production of:

Answer 45

acid from parietal cells

Question 46

adrenergic postganglionic sympathetic fibers innervate:

Answer 46

enteric neurons (both myenetric and submucosal plexus)

Question 47

what effect do adrenergic postganglionic sympathetic fibers have on gut motility?

Answer 47

inhibits gut motility

Question 48

occurs when bowel movements become less frequent and stools are difficult to pass

Answer 48

constipation

Question 49

substances that loosen stool or stimulate bowel movement

Answer 49

laxatives

Question 50

what are the four major kinds of laxatives?

Answer 50

- bulk forming laxatives - osmotic laxatives - lubricant laxative - stimulate laxatives

Question 51

contain naturally occuring plant fiber like psyllium and methyl cellulose that draw water into the stool to make them larger and easier to pass (must drink lots of water while taking)

Answer 51

bulk forming laxatives

Question 52

contain ingredients like polyethylene glycol or magnesium that draw fluid into the bowel from nearby tissue

Answer 52

osmotic laxatives

Question 53

glycerin suppositories (mineral oil) that coat the surface of stools or anus to make it easier for stools to pass

Answer 53

lubricant laxatives

Question 54

contain ingredients like senna and bisacodyl that cause the bowels to squeeze out the stools

Answer 54

stimulant laxatives

Question 55

loose, watery stool that occurs when the colon is unable to adequately absorb the liquid from ingested food/fluid

Answer 55

diarrhea

Question 56

diarrhea is usually caused by:

Answer 56

a bacterial or viral infection

Question 57

what is the most common OTC treatment for diarrhea?

Answer 57

loperamide and bismuth subsalicylate

Question 58

loperamide is a:

Answer 58

mu opioid agonist

Question 59

where in the GI tract are mu opioid receptors located?

Answer 59

on the myenteric plexus (controls peristalsis)

Question 60

true or false: loperamide has weak analgesic activity despite being a full agonist at the mu opioid receptor

Answer 60

true

Question 61

where is loperamide distributed to?

Answer 61

loperamide is widely distributed across the body, including the brain

Question 62

what makes lopermaide different from codeine?

Answer 62

less analgesia, less respiratory depression, no effect on cough

Question 63

loperamide is a substrate for:

Answer 63

P-glycoprotein (P-gp)

Question 64

where is P-glycoprotein (P-gp) located?

Answer 64

endothelial cells at the blood brain barrier (actively pumps drugs out of the brain)

Question 65

why isn't loperamide rewarding/addictive like morphine?

Answer 65

loperamide brain levels are kept low by P-gp activity

Question 66

P-glycoprotein (P-gp) is inhibited by:

Answer 66

tricyclic antidepressants (amitriptyline)

Question 67

blockin P-glycoprotein (P-gp) will increase brain concentration of:

Answer 67

loperamide