Intro to GI Physiology Flashcards
allow organs to function in syncytium
gap junctions
what is pharmacomechanical coupling
found in smooth muslce, ligand activation, activation of G protein, release Ca from intracellelar storage
what do Ca channel blockers do
disrupt GI motility by preventing rapid inward current depolarization
what causes depolarization of RMP in ENS
stretching, Ach, hormones
what causes hyperpolarization in RMP of ENS
sympathetic
what is effect of sympathetic innervation of GI
reduce blood flow, motility, and secretion
what is the main mediator of sympatheric innervation
NE
NE acts directly on
smooth muscle sphincter
reflexes from gut to paravertebral ganglia and back to gut
gastrocolic, enterogastric, colonoileal
reflexes from gut to spinal cord or brainstem and back to the gut
vagovagal, pain, defecation
controls contraction in GI muscle layers in response to food stimuli
vagovagal
T/F efferents that synapse with musculature are both inhibitory and stimulatory
T
T/F efferents that synapse with secretory are both inhibitory and stimulatory
False, only excitatory
motor, between longitudinal and circular
myenteric (auerbach’s plexus)
secretomotor, absent in esophagus
submucosal, meissner plexus
controls motility, contains excitatory and inhibtiory
myenteric
controls local secretion and absorption
submucosal
type of nuerons that is largests portion of auerback
AH
nueron that has nicotinic fast EPSP, greater excitability, resonds to tetradoxin (NA channel blocker)
S type
what is the second messenger of AH type cells
cAMP
what is the second messenger of S type cells
IP3 and Ca2+
what neurotransmitters evoke EPSP
Histamine, serotonin, substance P, Gastrin, CCK and ACh
Fast EPSP is mediated by ______ and couples with
ACh; ion channels
what are the slow IPSP
opioid, NE, galanin, adenosine
NE acts on what receptors
A2 adrenoreceptors, mimicked by somatostatin in meissners plexus
where does galanin work
auerbach
adenosine acts through what receptors
A1, low cAMP
what are the mediators of prsynaptic inhibition
CCK, ATP, histamine, NE, and ACH
_______ surpresses fast and slow EPSPs in myenteric plexus
serotonin
______ acts on muscarinic receptors to suppress its own release
ACh
main excitatory nuerotransmitters from the musclomotor
Ach and substance P
excitatorty secretomotor neurons release primarily
ACh and VIP
inhibitory nuerotransmitters
ATP, VIP, NO-inhibit circular
why is gastrin not affected by removal of the vagal nerve
itulizes GRP, not Ach
tip of villi are
hypoxic
