GI Physiology Exam 1 (IP3): Neuroendocrine Control of Gastrointestinal Function

(extrinsic/enteric) nervous system:

- sympathetic and parasympathetic nervous system

extrinsic

(extrinsic/enteric) nervous system:

- myenteric plexus

- submucosal plexus

enteric

what cells are the pacemakers of peristalsis

interstitial cells of cajal

the tone and activity of visceral smooth muscle is modulated by _______ and __________ input

neural, hormonal

interstitial cells of cajal are a hybrid of what two kind of cells?

neuron and smooth muscle

interstitial cells of cajal are electrically coupled to smooth muscle cells via ______ __________

gap junctions

what kind of cells generate the slow waves?

interstitial cells of cajal

T/F: muscle contraction occurs in the absence of action potentials

false

no muscle contraction occurs in the absence of action potentials

once the crest of the slow waves reach a critical point of depolarization, what two things occur

action potential, muscle contraction

intrinsic = (enteric/extrinsic)

enteric

the enteric/intrinsic nervous system is part of the __________ nervous system

autonomic

the (extrinsic/enteric) nervous system is the brain of the gut

enteric

in terms of the enteric nervous system:

afferent neurons = (integrating/response/sensory)

sensory

in terms of the enteric nervous system:

effector neurons = (integrating/response/sensory)

response

in terms of the enteric nervous system:

interneurons = (integrating/response/sensory)

integrating

enteric nervous system:

afferent neurons are local sensory neurons; primarily (adrenergic/cholinergic/dopaminergic) neurons with specialized processes

cholinergic

enteric nervous system:

what is the primary neurotransmitter for cholinergic neurons

acetycholine

enteric nervous system:

what three kind of receptors are found in the muscosa

chemoreceptors, osmoreceptors, mechnoreceptors

enteric nervous system:

what receptors are found in the muscle layers?

mechanoreceptors

enteric nervous system:

where are the synapses of afferent connections located?

at interneurons

majority of enteric interneurons are (cholinergic/adrenergic)

cholinergic

what is the job of enteric interneurons

integrating inputs

T/F: enteric interneurons integrate inputs both locally and from extrinsic nervous system

true

the main function of (afferent/efferent) neurons in the enteric nervous system is to promote digestion by stimulating propulsive peristalsis, net fluid accumulation in lumen, vasodilation of splanchnic vasculature, and enteroendocrine cell degranulation

efferent

vasodilation of splanchnic vasculature, supports fluid ________ and __________

absorption, secretion

net fluid accumulation in lumen:

- dissolution of nutrients; net = (increase/decrease) NaCl absorption (villi) + (increase/decrease) NaCl secretion (crypts)

decrease, increase

net fluid accumulation in lumen:

- dissolution of nutrients; net = decrease NaCl absorption (crypts/villi) + increase NaCl secretion (crypts/villi)

villi, crypts

enteroendocrine cell degranulation helps to provide additional _____ control of GI activity

hormone

what are the two major classes of effector neurons

cholinergic and inhibitory (noradrenergic/noncholinergic)

(cholinergic/inhibitory) neurons are responsible for contraction of longitudinal smooth muscle

cholinergic

(cholinergic/inhibitory) neurons are responsible for inhibiting circular smooth muscle contraction

inhibitory

inhibitory neurons, more specifically (vasoactive intestinal peptide/nitric oxide/adenosine triphosphate), are responsible for inhibiting circular smooth muscle contraction

nitric oxide

what are the three neurotransmitters listed in lecture that are secreted by the inhibitory effector neurons of the enteric nervous system

vasoactive intestinal peptide, nitric oxide, adenosine triphosphate

(cholinergic/inhibitory) neurons are responsible for enteroendocrine cell degranulation

cholinergic

(cholinergic/inhibitory) neurons are responsible for stimulation of NaCl secretion and inhibition of NaCl absorption

cholinergic

(cholinergic/inhibitory) neurons are responsible for stimulation of NaCl secretion and inhibition of NaCl absorption

inhibitory

(cholinergic/inhibitory) neurons are responsible for dilation of splanchnic vasculature

inhibitory

inhibitory neurons, more specifically (vasoactive intestinal peptide/nitric oxide/adenosine triphosphate), are responsible for stimulation of NaCl secretion and inhibition of NaCl absorption

vasoactive intestinal peptide

inhibitory neurons, more specifically (vasoactive intestinal peptide/nitric oxide/adenosine triphosphate), are responsible for dilation of splanchnic vasculature

nitric oxide

effector neurons act in concert with muscle layers to facilitate propulsive ___________

peristalsis

the (longitudinal/circular) smooth muscle layer has more baseline tone compared to the other

circular

the default state of longitudinal smooth muscle layer = (toned/relaxed)

relaxed

the default state of circular smooth muscle layer = (toned/relaxed)

toned

the main control of the circular smooth muscle layer is by (cholinergic/inhibitory) neurons

inhibitory

the main control of the longitudinal smooth muscle layer is by (cholinergic/inhibitory) neurons

cholinergic

with circular smooth muscle layers, relaxation via inhibitory neurons allows the lumen to what?

open up

with longitudinal smooth muscle layers, contraction via cholinergic neurons does what to the intestinal segments?

shortens them

when longitudinal smooth muscle is relaxed and circular smooth muscle is contracted, the lumen size is (increased/decreased) and retrograde (oral) movement is (maximized/minimized)

decreased, minimized

when longitudinal smooth muscle is contracted and circular smooth muscle is relaxed, the lumen size is (increased/decreased) and retrograde (oral) movement is (maximized/minimized)

increased, maximized

when longitudinal smooth muscle contracts, the gut wall is pulled back over the bolus, a term known as __________

sleeving

(enkephalinergic/serotonergic) enteric interneurons facilitate effector neuron action

serotonergic

serotonergic enteric interneurons (increase/decrease) propulsive peristalsis

increase

serotonergic enteric interneurons (increase/decrease) net fluid secretion

increase

carcinoid syndrome and inflammatory diarrhea are both diseases related to (enkephalinergic/serotonergic) enteric interneurons

serotonergic

(enkephalinergic/serotonergic) enteric interneurons establish a segmentation pattern

enkephalinergic

enkephalinergic enteric interneurons (activates/inhibits) effector neurons in alternating segments

inhibits

enkephalinergic enteric interneurons inhibits effector neurons which (increases/decreases) secretion and (increases/decreases) absorption

decreases, increases

the extrinsic nervous system has (sympathetic/parasympathetic) innervation

both

the extrinsic nervous system promotes digestion by coordinating the ________ nervous system, which makes it more efficient

enteric

(enteric/extrinsic) (sympathetic/parasympathetic) innervation provides the dominant extrinsic neural "tone" on alimentary tract

extrinsic, parasympathetic

the parasympathetic nervous system synapse with the (enteric/extrinsic) nervous system and (afferent/effector) neurons

enteric, effector

regarding the extrinsic nervous system, (sympathetic/parasympathetic) innervation has less dominant extrinsic neural "tone" on the alimentary tract except in "flight or fight" state or when activated in a long reflex

sympathetic

the main function of extrinsic sympathetic innervation is to inhibit ___________ and recover _______ _________

digestion, fluid volume

extrinsic sympathetic innervation (activates/inhibits) parasympathetic preganglionic nerves and enteric nervous system interneurons and effector neurons

inhibits

extrinsic sympathetic innervation inhibits parasympathetic preganglionic nerves and enteric nervous system interneurons and effector neurons which

- (speeds up/slows down) motility

- (increases/decreases) net fluid absorption

- (vasoconstriction/vasodilation) of splanchnic vasculature

- slows down

- increases

- vasoconstriction

general visceral afferent nerves of the extrinsic nervous system are (sensory/motor) nerves that transmit information from _________ __________ (viscera) to the ___________ nervous system

sensory, internal organs, central

general visceral afferent nerves of the extrinsic nervous system sense and carry impulses related to what kind of factors?

- stretch

- pressure

- chemical changes

- pain

(parasympathetic/sympathetic) nervous system: preganglionic neurons synapse in external ganglia and postganglionic neurons synapse with enteric nervous system plexi

sympathetic

(parasympathetic/sympathetic) nervous system: long preganglionic muscarinic neurons synapse with enteric nervous system plexi

parasympathetic

long reflexes of the GI tract are mediated by the (enteric/extrinsic) nervous system

extrinsic

long reflexes of the GI tract are mediated by the extrinsic nervous system. More specifically, coordination between activity of the _________ nervous system and the __________ nervous system

parasympathetic, sympathetic

the long reflexes of the GI tract regulate digesta passage over (long/short) intestinal distances

long

what is the stimulus for the gastrocolic reflex?

full stomach

gastrocolic reflex:

a full stomach signals general visceral afferent nerves to send signals to the central nervous system which (increases/decreases) parasympathetic nervous system and (increases/decreases) sympathetic nervous system activity at the colon

increases, decreases

the body's response to the gastrocolic reflex is to (decrease/increase) colonic motility

increase

the body's response to the gastrocolic reflex is to increase colonic motility which moves contents into the ___________

rectum

stimulating the long reflexes of the GI tract (slows/speeds) the transit of digesta through the GI tract

speeds

inhibiting the long reflexes of the GI tract (slows/speeds) the transit of digesta through the GI tract

slows

inhibiting the long reflexes of the GI tract slows the transit of digesta through the GI tract which prevents __________ of GI tract segments

overfilling

in order to slow the transit of digesta through the GI tract, general visceral afferent neurons send signals to the central nervous system which (increases/decreases) parasympathetic nervous system and (increases/decreases) sympathetic nervous system activity

decreases, increases

(enterogastric/enteroenteric/coloileal/ileogastric) reflex:

- Stimulus: Digesta in upper small intestine

- Response: Inhibition of gastric emptying

enterogastric

(enterogastric/enteroenteric/coloileal/ileogastric) reflex:

- Stimulus: Digesta in distal small intestine

- Response: Inhibition of intestinal peristalsis (oral site)

enteroenteric

the stimulus for the enterogastric reflex is digesta in the (distal/upper) (small/large) intestine

upper, small

the stimulus for the enteroenteric reflex is digesta in the (distal/upper) (small/large) intestine

distal, small

the response for the enterogastric reflex is (activation/inhibiton) of gastric emptying

inhibition

the response for the enteroenteric reflex is (activation/inhibiton) of intestinal peristalsis

inhibition

(enterogastric/enteroenteric/coloileal/ileogastric) reflex:

stimulus: full colon

response: inhibition of ileal emptying

coloileal

(enterogastric/enteroenteric/coloileal/ileogastric) reflex:

stimulus: full ileum

response: inhibition of gastric emptying

ileogastric

the stimulus for the coloileal reflex is an (empty/full) stomach

full

the response for the coloileal reflex is (activation/inhibition) of ileal (filling/emptying)

inhibition, emptying

the stimulus for the ileogastric reflex is an (empty/full) illeum

full

the response for the ileogastric reflex is (activation/inhibition) of gastric (filling/emptying)

inhibition, emptying

what is the largest endocrine organ in the body?

the gut