Lecture 1: Enteric Nervous System

what are the main functions of the GI system?

digest and absorb nutrients

what are the two major networks of the ENS?

myenteric and submucosal plexi

where is the submucosal plexus found?

submucosal layer

where is the myenteric plexus found?

muscularis layer between longitudinal and circular muscle

T/F: the ENS can receive input from the CNS, but can also act independently of the CNS

true

what are the 3 major types of neurons in the ENS?

IPANs

motor

interneurons

which neurons in the ENS are the first to detect changes in the GI?

IPANs

where are IPANs found and what are they very sensitive to?

submucosal and myenteric plexi

mechanical distortion

what are the primary neurotransmitters of IPANs?

Ach

calcitonin-gene related peptide

tachykinin

where are motor neurons found?

circular and longitudinal muscle layers

what are the 5 types of motor neurons?

excitatory

inhibitory

secretomotor

vasomotor

EEC innervating neurons

what are the two types of interneurons? where is their input from?

ascending - from IPANs

descending- MMC of SI

where are interneurons located? what is their primary neurotransmitter?

myenteric plexus

Ach

list supporting cells of the ENS

enteriic glia

intersitital cells of cajal

where are enteric glia found?

myenteric and submucosal plexus

what is the overall function of enteric glia?

maintain homeostasis

what can activate enteric glia? what is their overall function?

Ach, catecholamines, glutamate, adenosine, serotonin

interstitial cells of cajal (ICCs) are the pacemakers of the GI. what do they have receptors for?

tachykinins, NO, 5-HT

function of enteroendocrine cells

synthesize and store GI hormones

where are enteroendocrine cells found? in which location are they open to the lumen? closed?

epithelial layer of GI tract (open)

pancreatic islets (closed)

T/F: enteroendocrine cells cannot communicate using paracrine signaling

false, long cytoplasmic processes

endocrine signaling

delivery of a peptide hormone through circulation to distant target cell

paracrine signaling

affect function of adjacent cell

autocrine signaling

hormonal influence of a cell on itself

neurocrine signaling

secreted by neurons of GI, following an AP to act on target cell