B5-094 GI Physiology I Flashcards
major spinchters of the GI tract
5
- upper esophageal
- lower esophageal
- pyloric
- ileocecal
- internal and external anal spinchters
from I cells in duodenum and jejunum and neurons in ileum and colon
CCK
increases enzyme secretion from pancreas
CCK
increases gallbladder contraction
CCK
released from K cells in duodenum and jejunum
GIP
- decreases fluid absorption in pancreas (exocrine)
- increases insulin release from pancreas (endocrine)
GIP
released from G cells in the antrum of stomach
gastrin
increases H+ secretion via the parietal cells in the body of the stomach
gastrin
released from vagal nerve endings
GRP
increases gastrin release from the G cells in antrum of stomach
GRP
released from endocrine cells in the upper GI tract
motilin
increases smooth muscle contraction of esophageal spinchters, stomach, duodenum
motilin
released from S cells in small intestine
secretin
increases HCO3- and fluid secretions by pancreatic ducts
secretin
decreases gastric acid secretion in stomach
secretin
released by D cells of stomach and duodenum, pancreatic islet cells
somatostatin
inhibits gastrin release
somtatostatin
- increases fluid absorption, decreases secretion
- increases smooth muscle contraction in small intestine
somatostatin
decreases pancreatic secretions
somatostatin
decreases bile flow from liver
somatostatin
released from L cells in ileum and large intestine
GLP-1
reduces gastric empyting, gastric acid secretion, and gastric motility
GLP-1
released from ENS neurons
VIP
increases smooth muscle relaxation and secretion in small intestine
VIP
increases secretions from pancreas
VIP
produced in antrum, duodenum, and jejunum
gastrin
produced in duodenum, jejunum, and ileum
2
CCK
secretin
produced in duodenum and jejunum
2
GIP
motilin
what pattern of motility moves material orally and aborally?
isolated contraction
what pattern of GI motility mixes material?
segmentation
what pattern of GI motility requires coordinated contraction and relaxation to move the material aborally?
peristalsis
describe the peristaltic reflex
- distension is sensed by intrinsic afferent neurons
- stimulate interneurons to contract proximal to bolus through excitatory neurons
- intrinsic afferent neurons inhibit the segment distal to the bolus causing relaxation
stimulate muscles of the enteric nervous system to contract
Ach
stimulates muscles of the enteric nervous system to relax
2
VIP
NO
describe movement of food through the pharynx and upper esophagus during swallowing
- tongue pushes food to back of mouth
- soft palate blocks nasal passage
- epiglottis covers the glottis
- bolus descends into esophagus
generally describe the vagovagal reflex
afferent (sensory) -> hindbrain -> efferent (motor)
function to coordinate chewing, salivation, swallowing
control digestive processes in oral cavity
mechanoreceptors
decreasing […] pressure helps to move the food bolus down the esophagus during primary peristalsis
luminal pressure
mechanosensory control of the esophagus regulates
3
- peristalsis
- spinchter tone
- gastric compensation
allows for the expansion of the stomach by food, without changing intraluminal pressure
compensation
requires vagal innervation
compenstation of the stomach requires […] innervation
vagal
bolus […] impacts the rate of gastric empyting
composition
oleate>acid>saline
describe the mechanical actions of the stomach on its contents
- propulsion: bolus pushed toward closed pylorus
- grinding: antrum chruns the trapped material
- retropulsion: bolus pushed back into the proximal stomach