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11 Cards in this Set

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Name and define the 4 basic fx of GI sys
motility
secretion: gastric juices from exocrine gland and hormones from endocrine gland to regulate GI
digestion: degrade foods by digestive enzymes
absorption
List the primary and accessory digestive organs
Primary: mouth, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (cecum, appendix, colon, rectum), anal canal

Accessory organs: salivary glands, exocrine pancreas, biliary sys: gb and liver, endocrine
Describe the function of sphincters in the GI system
pharyngoesophageal sphincter (UES): separates mouth/pharynx and esophagus
gastroesophageal sphincter (LES): separates esophagus and stomach
pyloric sphincter/valve: separates stomach and small intestine
Sphincter of Oddi: separates pancreas and small intestine
ileocecal sphincter/valve: separates small intestine and large intesine
internal anal sphincter: involuntary
external anal sphincter: voluntary from pelvic nerves keep content in rectum
Gastrin
source
primary stimulus for secretion
function
G cells of stomach, duodenum
stimulated by protein in stomach, stretch and vagus nerves
Fx: stimulates HCl secretion from parietal cells and pepsinogen from chief cells
is trophic to stomach and small Int.
enhances gastic motility
constricts pyloric sphincter to inhibit gastric emptying
stimulates ileal motility
relaxes ileocecal sphincter > induces colonic mass movement
causes gallbladder contraction
enhances pancreatic secretion
Secretin
source
primary stimulus for secretion
function
S cells duodenum jejunum
stimulated by acid in DUODENUM
stimulates aqueous NaHCO3 secretion by pancreatic duct cells
simtulates aq. NaHCO3 rich bile by liver
Inhibits gastric acid secretion
is trophic to exocrine pancreas
inhibits gastic emptying by increasing pyloric constriction and reduces antral contraction
stimulates gastric pepsinogen secretion
CCK
source
primary stimulus for secretion
function
I cell in duodenum and jejunum
stimulated by fat, protein in duodenum and nerves

stimulates digestive enzyme secretion by pancreatic acinar cells (trypsin, chymotrypsin, elastase, carboxypeptidase, aminopeptidase, amylase, lipase)

stimulates pancreatic NaHCO3 secretion
causes gallbladder contraction
inhibits gastric emptying = pyloric constriction
is trophic to exocrine pancreas
inhibits gastric acid secretion
stimulates gastric pepsinogen secretion
stimulates bile secretion
causes relaxation of shincter of Oddi
GIP
source
primary stimulus for secretion
function
from K cells in duodenum and jejunum
stimulated by fat, glucose, acid, hypertonicity and distension
inhibits gastric acid secretion
stimulates insulin secretion by endocrine pancreas
inhibits gastric emptying = pyloric constriction
State the part of the digestive tract and the primary fx of each
Mucosa
Epithelium-stratified squamous non-keratinizing or simple columnar with or without a brush border.
Lamina Propria- loose areolar connective tissue wiht lymph
Muscularis mucosa - thin inner circular, thick outer longitudinal
Submucosa
dense irreg. conn. tissue with mucous glands and lymph tissue
meissner's/submucosal nerve plexus-parasymp for mucosa
Muscularis
inner circular, outer longitudinal with inner oblique in stomach - has myenteri/Auerbach's plexus - Teniae coli - 3 longitudinal layers
Serosa
simple squamous mesothelium and adventia of loose conn. tissue blending with surrounding tissue
Compare the tubular organs of the digestive tract with respect to the structure of each layer and relate any structural variations to diff in structure
esophagus is nonkeratinized stratified squamous epithelium
stomach is simple columnar epithelium that secrete mucus. No goblet cells. has rugae when empty
small intestine is simple columnar epithelium with brush border, plica circulares/valves of Kerckring, villi, intestinal simple tubular glands called crypts of Lieberkuhn
Large intestine is simple columnar absorptive cells with short microvilli many goblet cells and crypts of Liebberkuhn lined by columnar absorptive cells
describe the general patters of GI motility
tonic contractions: sphincters and esophagus
propulsive peristalsis: antrum of stomach, sm. In. and rectum
reverse peristalsis: proximal colon
MMC: fasting/empty sm. Int.
Mass movements: colon
Nonpropulsive segmentation: small intestine
Haustration: colon
explain the sequence of events during swallowing
oral/voluntary: food bolus moved to pharynx by tongue
pharyngeal: soft palate covers nasopharynx and epiglottis covers glottis to close trachea. UES relaxes. can't breathe during this time
Esophageal: peristaltic waves moves food through the esophagus