Physiology

Question 1

unitary smooth muscle characteristics

Answer 1

• spontaneous contraction
• activated by stretch or distention
• found in stomach and intestine

Question 2

multi-unit smooth muscle features

Answer 2

• requires direct neural or hormonal stimulation
• lacks spontaneous contraction
• found in esophagus and gallbladder

Question 3

spike potentials

Answer 3

• generate contractile events

- increase in Ca leads to increased spike potentials and vice versa

Question 4

submucosal (Meissner’s plexus)

Answer 4

• between circular muscle and submucosal layers
• functions largely in secretion
• only excitatory

Question 5

myenteric (Auerbach’s plexus)

Answer 5

• between muscle layers
• regulates contraction
• excitatory and inhibitory

Question 6

inhibitory NTs

Answer 6

• VIP and NO

Question 7

excitatory NTs

Answer 7

• ACh and substance P

Question 8

hormonal vasodilators

Answer 8

• CCK, VIP, gastrin, secretin, kinins, decreased oxygen levels leading to increased adenosine

Question 9

action of gastrin

Answer 9

• increases gastric H secretion
• increases growth of gastric mucosa
• increases gastric motility

Question 10

regulation of gastrin

Answer 10

• increased by stomach distention, akalinization, amino acids, peptides, vagal stimulation
• decreased by stomach pH <1.5

Question 11

CCK action

Answer 11

• increases pancreatic secretion
• increases gallbladder contraction
• decreases gastric emptying
• increases sphincter of Oddi relaxation

Question 12

CCK regulation

Answer 12

• increased by fatty acids and amino acids

Question 13

action of secretin

Answer 13

• increases pancreatic HCO3
• decreased gastric acid secretion
• increases bile secretion

Question 14

regulation of secretin

Answer 14

• increased by acid, fatty acids in lumen of duodenum

Question 15

action of somatostatin

Answer 15

• decreases gastric acid and pepsinogen secretion
• decreased pancreatic and small intestinal fluid secretion
• decreases gallbladder contraction
• decreases insulin and glucagon secretion

Question 16

regulation of somatostatin

Answer 16

• increased by acid

- decreased by vagal stimulation

Question 17

VIP action

Answer 17

• increases intestinal water and electrolyte secretion

- increases relaxation of intestinal smooth muscle and sphincters

Question 18

VIP regulation

Answer 18

• increased by distention and vagal stimulation

- decreased by adrenergic input

Question 19

NO action

Answer 19

• increases smooth muscle relaxation, including LES

Question 20

motilin action

Answer 20

• produces migrating motor complexes (MMCs)

Question 21

motiln regulation

Answer 21

• increased in fasting state

Question 22

three stages of swallowing

Answer 22

• voluntary
• pharyngeal
• esophageal

Question 23

voluntary swallowing

Answer 23

• tongue pushes food towards back of the mouth

Question 24

pharyngeal swallowing

Answer 24

• efferents sent through CNs (ACh)
• soft palate moves over nasopharynx
• trachea closes off
• UES relaxes

Question 25

esophageal swallowing

Answer 25

- primary peristalsis is simply the continuation of the peristaltic wave that begins in the pharynx and spreads into the esophagus during the pharyngeal stage of swallowing - secondary peristaltic waves result from distention of the esophagus itself by the retained food

Question 26

delayed emptying: vagal neuropathy or DM

Answer 26

- gastroparesis | - delayed emptying of solids

Question 27

MMC

Answer 27

- migrating myoelectric complexes - electrical oscillations fire spike potentials leading to contractions - motilin released at onset of MMC - MMCs are terminated by ingesting food, CCK and gastrin

Question 28

peristaltic rush

Answer 28

- longer waves of contraction brought on by irritation, excessive distention, extrinsic and intrinsic neural control

Question 29

power propulsion (mass movements)

Answer 29

- programmed motor event of the ENS - last 18-20 seconds - cramping maybe associated - occur about 15 minutes after a meal - provoke the urge to defacate

Question 30

hyperthryoidism

Answer 30

- increases GI motility and may result in diarrhea

Question 31

hypothyroidism

Answer 31

- decreases GI motility and may result in constipation

Question 32

function of mucins

Answer 32

- lubricate and protect | - creates a bolus

Question 33

activators of HCl secretion

Answer 33

- histamine - gastrin - ACh

Question 34

inhibitors of HCl secretion

Answer 34

- somatostatin | - prostaglandins

Question 35

achlorhydria

Answer 35

- dysfunction of parietal cells caused by antibodies or use of PPIs - results in increased susceptibility to infection, malabsorption and diarrhea

Question 36

inhibitors of gastric acid secretion

Answer 36

- distention of small bowel - acid in duodenum - protein digestion products - irritation

Question 37

activators of chief cells

Answer 37

- neural: ACh, VIP | - hormonal: gastrin, CCK, secretin, GIP