midterm

Question 1

which structures produce gastrin

Answer 1

G cells of the stomach produce gastrin after eating a meal

Question 2

which structures produce CCK?

Answer 2

CCK (Cholecystokinin )

• secreted by “I” cells in the mucosa of the duodenum and jejunum
• response to consumption of fats, fatty acids, and monoglycerides

Question 3

which structure(s) produce secretin?

Answer 3

• first gastrointestinal hormone discovered
• secreted by the S cells in response to gastric acid presence
• found in the mucosa of the duodenum
• effects motility

Question 4

which structures produce motilin?

Answer 4

• secreted by the upper duodenum during fasting

- increase motility by cyclically releasing motilin

Question 5

CCK

Answer 5

released from cells in duodenum and jejunum – stimulated by digestion of fats

Question 6

which factors have a direct action on the parietal cells to stimulate acid secretion

Answer 6

The rate and formation of hydrochloric acid by the parietal cells is directly related to the amount of histamine secreted by the ECL (enterochromatin-like cells)

Question 7

what is the main excitatory neurotransmitter to gut smooth muscle ?

Answer 7

ACH

Acetylcholine

Question 8

what is the stimulatory and inhibitory effects of gastrin are modified and by which substance?

Answer 8

the major inhibitory neurotransmitter to gut smooth muscle is norepinephrine

Question 9

what are the segments of the small intestine from outside to into the lumen

Answer 9

serosa, longitudinal muscle, circular muscle, submucosa, mucosa, epithelial lining, lumen
(some. long. cocks. stretch. eager. ladies)

Question 10

what are the hormone secreting cells of the GI tract

Answer 10

• enteroendocrine cells are the hormone secreting cells of the GI tract, located in stomach, pancreas, and small intestine.

Question 11

which hormone(s) is secreted after eating a meal high in fat

Answer 11

cholecystokinin (CTC) is secreted by “I” cells in the mucosa of duodenum & jejunum

Question 12

myenteric plexus

Answer 12

mostly linear chain of many interconnecting neurons
o increased tonic contraction “tone of gut wall
o increased intensity of rhythmical contractions
o slightly increased rate of rhythm of contraction
o increased velocity of conduction of excitatory waves along gut wall-→ causing more rapid movement of gut peristaltic waves

Question 13

slow wave frequency

Answer 13

rhythm of most gastrointestinal contractions determined by frequency of smooth muscle membrane potential (slow-waves)

Question 14

spike action potentials:

Answer 14

true action potentials, occur automatically when resting membrane potential of gastrointestinal smooth muscle becomes more positive than about -40 millivolts.

Question 15

phases of swallowing

Answer 15

• *Swallowing** Voluntary Phase which initiates swallowing process ->
• *Pharyngeal Phase** going from pharynx to esophagus(involuntary phase is controlled by the brainstem, medulla, and pons) ->
• *Esophageal** phase going from esophagus to stomach (broken into primary peristalsis – continuation of pharyngeal peristalsis and secondary – induced by distention that repeats until bolus is cleared)

Question 16

how does the sympathetic nervous system effect gut motility

Answer 16

the sympathetic nervous system inhibits gut motility

Question 17

how does the parasympathetic nervous system effect gut motility ?

Answer 17

the parasympathetic nervous system stimulates gut motility

Question 18

what are the three levels of control of the defecation reflex and which parts control internal versus external anal sphincters

Answer 18

• 1. Intrinsic reflex mediated by ENS – distention, contractions – 1 and 2 are dependent on one another
• 2. Spinal cord reflex by S2-S4 – intensifies intrinsic reflex – 1 and 2 are dependent on one another.
• 3. Higher centers requires intact spinal cord – deep breathing, closure of glottis, increase of abdominal pressure to propel fecal contents downward.

Question 19

Upper esophageal sphincter

Answer 19

keeps air from entering

esophagus

Question 20

Lower esophageal sphincter

Answer 20

keeps acid from refluxi

ng into esophagus

Question 21

Upper rectal sphincter

Answer 21

– involuntary smooth muscle gradual increase in defecation reflex

Question 22

Lower rectal sphincter

Answer 22

voluntary skeletal muscle

Question 23

Diverticulosis

Answer 23

outpouchings in colon When inflamed causes Diverticulitis – strong genetic component, can be induced by stress, painful and can cause sepsis, occurs in 10-25% of people with diverticulosis, infection caused by stool on bacteria getting caught in diverticula