Phys- Neural Factors

Question 1

The ____ is the innermost layer of smooth muscle cells.

Answer 1

muscularis mucosa

Question 2

Contraction results in folding _____ of the entire mucosal layer, which _____ exposure of epithelial cells to luminal contents.

Answer 2

fluctuations

increases

Question 3

Contraction of the muscle layers of the muscularis exerna are primarily responsible for the __ and ___ of luminal contents.

Answer 3

mixing

propulsion

Question 4

The submucosal plexus (Meissner’s plexus) is best developed where?

Answer 4

small intestine

Question 5

The myenteric plexus (Auerbach’s plexus) is located where and best developed where?

Answer 5

between the circular longitudinal smooth muscle layer of the muscularis externa

entire gut length

Question 6

Interneurons within the plexuses connect ____ sensory fibers to ___ fibers innervation smooth muscle cells and secretory cells and create local reflex arcs within the GI tract.

Answer 6

afferent

efferent

Question 7

The presence of extrinsic nerves from the autonomic nervous system is necessary for ____ of most GI functions.

Answer 7

coordination

Question 8

Afferent fibers from ____ and ____ within the gut wall run to the CNS, which then influence central neural control of the GI tract as well as elicit _____ via the ENS.

Answer 8

chemoreceptors

mechanoreceptors

local reflexes

Question 9

Parasympathetic innervation to the GI tract is nerve fibers from what nerves?

Answer 9

vagus and pelvic (sacral)

vagus above and including transverse colon, below transverse colon is pelvic

Question 10

Preganglionic fibers terminate mostly on the ganglia of the intramural plexuses and share their postganglionic neurons with the ENS. They are mostly what?

Answer 10

cholinergic

Question 11

Activation of parasympathetic nerves (vagus) is most often ____ and ____ either ___ or ____.

Answer 11

excitatory
increasing
motility
secretion

Question 12

Release of VIP (and NO) ____ _____ of GI smooth muscle. ACh (and SubP) released from postganglionic neurons ____ ____.

Answer 12

inhibit contraction

excites contraction

Question 13

Activation of sympathetic nerves usually results in ___ of motor and secretory activity.

Answer 13

inhibition

Question 14

NE is released in the ____ plexus, ____ parasympathetic ___ release by activating alpha2 presynaptic receptors.

Answer 14

submucosal, inhibits, ACh

Question 15

Pathways which influence the muscularis externa (_____) and muscularis mucosae (______) act though the intramural plexuses.

Answer 15

inhibitory

stimulating

Question 16

Sympathetic fibers innervate blood vessels of the gut directly causing ____ and is ___ receptor mediated.

Answer 16

vasoconstriction

alpha 1

Question 17

GI smooth muscle is therefore, an example of ____ smooth muscle. The ____ of the cells in adjacent muscle bundles is a major determinant of how far the electrical signal is transmitted down the GI tract.

Answer 17

single unit

excitability

Question 18

The BER varies from ___/min in the stomach to __/min in the duodenum. The BER of each segment is set by a group of faster cells called what?

Answer 18

3
12
pacemakers

Question 19

The ___ of the slow waves can be modulated by intrinsic and extrinsic neural input. Sympathetic ______, parasympathetic stimulation ______.

Answer 19

amplitude

decreases amplitude

increases amplitude

Question 20

The initial rising phase of the action potential is due primarily to ___ entry into the cell through L-type ___ channels.

Answer 20

Ca^2+

Ca^2+

Question 21

Extracellular calcium entering ___ smooth muscle cells during an action potential is a major source of calcium for ___.

Answer 21

visceral

contraction

Question 22

Does the stomach need an action potential to contract? What about the intestine?

Answer 22

no

yes the intestine does