mechanisms of GI motility Flashcards
what is the main muscle in the GI tract
mainly smooth muscle but some skeletal
what is gut motility controlled by
ENS and some extrinsic control by ANS
what is the myenteric plexus involved in and influenced by
muscle contraction
ANS
what is the submucosal plexus involved in
sensory functions and local responses to the stimulation of sensory nerve endings in the mucosa
What neurons are the enteric NS composed of
motor, interneurons and sensory
ENS- where do the motor neurones go
smooth muscle
intrinsic arterioles
cells regulating acid secretion
enteroendocrine cells
where are enteroendorine cells and what do they do
inside the epithelium
sense what is coming into the lumen and respond by secreting hormones that can signal to brain or pancreas
ENS- interneurons function
sit between plexuses or join muscle to plexus and allow coordination of reflexes
ENS- sensory neurones
2 types
chemoreceptors- sensitive to pH
mechanoreceptors- detect distention of gut so can tell where food is and can control peristaltic movement
ENS what is it mainly controlled by
ANS and some somatic motor neurons are involved where striated muscle is involved
what are the types of sphincters in the GI tract
upper and lower oesophageal
pyloric
ileo-caecal
anal - internal and external
what muscle is the top 1/3 of the oesophagus `
striated skeletal
what muscle is the bottom 2/3 of the oesophagus `
smooth
how is upper striated muscle innervated
controlled by brainstem swallowing centre and its motor neurons
what is bottom SM of oesophagus innervated by
vagus nerve that synapses with the ENS
