GI function

Question 1

What percentage of drugs are given by the oral route?

Answer 1

80%

Question 2

What is the second deadliest cancer in the US?

Answer 2

colorectal cancer

Question 3

The GI tract starts at the ______ and ends at the _____

Answer 3

mouth and anus

Question 4

What are three GI tract accessory organs?

Answer 4

liver, gallbladder pancreas

Question 5

What are the five layers of the GI wall?

Answer 5

serosa, muscularis, submucosa, mucosa, epithelial lining

Question 6

The muscularis layer includes _______ muscle that traverses the length of the GI tract and ______ muscle that exists in localized rings.

Answer 6

longitudinal and circular

Question 7

In what GI wall layer is the myenteric nerve plexus located?

Answer 7

muscularis (between longitudinal and circular layers)

Question 8

Which GI wall layer has contact with the contents of the lumen?

Answer 8

epithelial lining

Question 9

In what GI wall layer is the submucosal plexus located?

Answer 9

submucosa

Question 10

What is mesentary?

Answer 10

helps attach the GI tract to the inside cavity

Question 11

Which GI wall layer has many fold and contains glands and microvilli?

Answer 11

mucosa

Question 12

A _________ is a fusion of fiber bundles partly separated by loose connective tissue that functions as a unit (usually).

Answer 12

syncytium

Question 13

What are tonic contractions?

Answer 13

when the muscle stays contracted for a long time

Question 14

With slow waves of depolarization, does a muscle contraction usually occur? Why or why not?

Answer 14

No, because there isn’t a great enough change in membrane potential for contractions

Question 15

What is the purpose of a migrating motor complex (MMC)?

Answer 15

to facilitate emptying of GI contents

Question 16

Tonic contractions can be caused by prolonged exposure to ________

Answer 16

calcium

Question 17

Which kind of potentials usually lead to contractions of muscle?

Answer 17

spike potentials

Question 18

What is the only place in the GI tract where slow depolarization waves result in muscle contractions?

Answer 18

stomach

Question 19

Is the fixed frequency of slow waves of depolarization the same everywhere in the GI tract?

Answer 19

no

Question 20

Voltage-dependent _______-______ channels exist in the smooth muscle.

Answer 20

calcium, sodium

Question 21

Entry of _____ causes contraction

Answer 21

calcium

Question 22

What are three things that stimulate depolarization (action potential beginning)?

Answer 22

stretching of muscle, stimulation by acetylcholine (parasympathetic nerves), stimulation by gastrointestinal hormones

Question 23

What is one thing that stimulates hyperpolarization?

Answer 23

stimulation of fiber membranes by norepinephrine/epinephrine

Question 24

What are three causes of tonic contractions?

Answer 24

continuous, repetitive spike potentials, hormones/factors that result in partial depolarization (but not action potentials), continuous entry of calcium into the cell

Question 25

Is the Migrating Motor Complex (MMC) during fasted or fed conditions?

Answer 25

fasting

Question 26

Which two plexuses are part of the enteric nervous system?

Answer 26

myenteric (auerbach's), submucosal (meissner's)

Question 27

What does the submucosal plexus control?

Answer 27

movement of mucosal folds, glands/epithelial cells, local blood flow (concerned with local movement)

Question 28

The ________ plexus has neurons that extend the entire length of the GI tract, while the _______ plexus has neurons within segments of the GI tract for local control.

Answer 28

myenteric and submucosal

Question 29

What two things does the myenteric plexus stimulate?

Answer 29

increased tonic contractions, increased intensity/rate of rhythmical contractions

Question 30

What does the myenteric plexus inhibit?

Answer 30

pyloric sphincter (stomach to duodenum, prevents acidic material from spilling out), sphincter of ileocecal valve (small intestine-ileum to cecum, prevents backflow in intestines)

Question 31

What are three things that stimulate sensory afferent neurons (carry info to CNS)?

Answer 31

distention of gut wall, irritation of gut wall (nonspecific), specific chemical stimuli

Question 32

The sympathetic GI innervation is mainly ____ganglionic, while the parasympathetic GI innervation is mainly ____ganglionic.

Answer 32

post and pre

Question 33

The ________ innervation is mainly concerned with inhibition in the GI tract; what chemicals are used in inhibition?

Answer 33

sympathetic, norepinephrine, epinephrine

Question 34

The ______ innervation is mainly concerned with stimulation in the GI tract; what chemical is used in stimulation?

Answer 34

parasympathetic, acetylcholine

Question 35

What are the two types of functional movement in the GI tract?

Answer 35

propulsive, mixing movements

Question 36

What is the Law of the Gut?

Answer 36

propulsive movements move food away from mouth (except with vomiting)

Question 37

Which plexus is required for peristalsis?

Answer 37

myenteric

Question 38

_________ GI reflexes involve more than 1 segment in the GI tract (ex.: gastrocolic involves stomach and colon).

Answer 38

long loop

Question 39

What are the two types of GI reflexes?

Answer 39

local, long loop

Question 40

Pain reflexes result in overall ________ of the GI tract.

Answer 40

inhibition

Question 41

What are three processes that local GI reflexes can affect (increase or decrease)?

Answer 41

secretion, peristalsis, mixing movements

Question 42

Which has a longer lasting effect: neurotransmitters or GI hormones?

Answer 42

GI hormones

Question 43

What are five GI hormones?

Answer 43

secretin, gastrin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), motilin

Question 44

When and where is gastrin released?

Answer 44

in response to a meal (when), from G cells in stomach, duodenum, and jejunum (where)

Question 45

What are some things that stimulate the release of gastrin?

Answer 45

protein digestion products, distention, gastrin releasing peptide

Question 46

What are the physiological effects of gastrin?

Answer 46

increased acid secretion, increased growth of the mucosa

Question 47

What inhibits gastrin secretion?

Answer 47

acidification of the stomach

Question 48

Where is cholecystokinin (CCK) released from?

Answer 48

I cells in duodenum/jejunum

Question 49

What are three things that stimulate release of CCK?

Answer 49

digestive products of fat (fatty acids or monoglycerides), peptides and single amino acids, weak acid in the intestine

Question 50

The presence of _______ does NOT stimulate release of CCK.

Answer 50

triglycerides

Question 51

What are the physiological effects of CCK?

Answer 51

emptying gallbladder (contracts gallbladder, relaxes sphincter of Oddi), stimulates pancreatic enzyme secretion, stimulates pancreatic bicarbonate secretion (weakly), inhibits gastric emptying, inhibits appetite, increases grow of pancreas/gallbladder mucosa

Question 52

Once the ___________ is open, the gallbladder can empty.

Answer 52

sphincter of Oddi

Question 53

Where is secretin release from?

Answer 53

S cells of duodenum/jejunum/ileum mucosa

Question 54

What stimulates the release of secretin?

Answer 54

acid in duodenum, fatty acids in duodenum

Question 55

What are the physiological effects of secretin?

Answer 55

inhibits gastric acid secretion, stimulates pancreatic and bile bicarbonate secretion, stimulates pepsin secretion in stomach

Question 56

Where is gastric inhibitory peptide released from?

Answer 56

duodenum, proximal jejunum

Question 57

What are the physiological effects of gastic inhibitory peptide?

Answer 57

stimulates insulin release, inhibits gastric acid secretion

Question 58

When and where is motilin released?

Answer 58

during fasting, from duodenum, proximal jejunum

Question 59

What is the physiological effect of motilin?

Answer 59

stimulates upper GI motility (migratin motor complex)