Gastro Phys Flashcards
Somatostatin: where it’s secreted, stimuli, actions
Secreted by D cells of GI mucosa (also hypothalamus and pancreas)
Stimulated by low luminal pH
Actions: inhibits gastric H+ secretion
Histamine: where it’s secreted, its target, actions
Secreted by enterochromaffin-like cells in gastric glands
Target is parietal cells
Action: stimulates H+ production
Gastrin: where it’s secreted, stimuli, actions
Secreted by G cells of the stomach
Stimulated by small peptides and AA’s, distention of the stomach, and vagal stimulation via GRP
Actions: increase gastric H+ secretion, growth of gastric mucosa
CCK: where it’s secreted, stimuli, actions
Secreted by I cells of the duodenum and jejunum
Stimulated by small peptides, AA’s, and FA’s
Actions: increase pancreatic enzyme and HCO3- secretion, contraction of gallbladder and relaxation of sphincter of Oddi, growth of exocrine pancreas and gallbladder, inhibits gastric emptying, paracrine signal
Secretin: where it’s secreted, stimuli, actions
Secreted by S cells of the duodenum
Stimulated by H+ and FA’s in the duodenum
Actions: increase pancreatic and biliary HCO3- secretion, decrease gastric H+ secretion, inhibits gastrin, can act as paracrine signal
GIP: where it’s secreted, stimuli, actions
Secreted by duodenum and jejunum
Stimulated by FA’s, AA’s, and oral glucose
Actions: increase insulin secretion from pancreatic beta cells (incretin effect), decrease gastric H+ secretion
ACh actions
Contraction of SM in wall (increases amplitude of slow waves) Relaxation of sphincters Increase salivary secretion Increase gastric secretion Increase pancreatic secretion
NE actions
Relaxation of SM in wall (decreases amplitude of slow waves)
Contraction of sphincters
Increase salivary secretion
VIP actions
Relaxation of SM
Increase intestinal secretion
Increase pancreatic secretion
NO actions
Relaxation of SM
GRP actions
Increase gastrin secretion
Action of enkephalins
Contraction of SM
Decrease intestinal secretion
Action of neuropeptide Y
Relaxation of SM
Decrease intestinal secretion
Action of substance P
Contraction of SM
Increase salivary secretion
Secreted with ACh
Innervation of most mastication muscles
CN V - trigeminal n.
Controlled by nuclei in brainstem
Achalasia due to lack of:
VIP or NO
LES cannot fully relax
Parasympathetic regulation of contractions
Gastrin and motilin
Increase AP and force of contractions
Sympathetic regulation of contractions
Secretin and GIP
Decreases AP and force of contractions
Factors that increase gastric emptying
Decrease distensibility
Increase force of peristaltic contractions of the caudad stomach
Decrease tone of pylorus
Increase diameter and inhibition of the segmenting contractions of the proximal duodenum
Factors that inhibit gastric emptying
Relaxation of orad (increased distensibility)
Decrease force of peristaltic contractions
Increase tone of pyloric sphincter
Segmentation contractions in intestine (entero-gastric reflex)
Main hormone in peristaltic reflex
Serotonin 5-HT
Released by enterochromaffin cells
Binds to IPANs
Effect of prostaglandins on contractions
Increase
Effect of E and glucagon on contractions
Inhibit
Areas innervated by vagus n.
Parasympathetic
Cecum, ascending/transverse colon
Areas innervated by pelvic n.’s
Parasympathetic
Descending/sigmoid colon, rectum
Areas innervated by superior mesenteric ganglion
Sympathetic
Proximal regions
Areas innervated by inferior mesenteric ganglion
Sympathetic
Distal regions
Areas innervated by hypogastric plexus
Sympathetic
Distal rectum and anal canal
Areas innervated by somatic pudendal n.’s
External anal sphincter
