Module 13 general anatomy Flashcards
pharynx
propel food into esophagus
oral cavity, teeth, tongue
mechanical breakdown, mixing with salivary secretions
salivary glands
secretion of lubricating fluid containing enzymes that initiate digestion
Liver
secretion of bile storage of nutrients production of: - cellular fuels - plasma proteins, - clotting factors detoxification phagocytosis
Esophagus
transport of food into the stomach
Pancreas
secretion of buffers and digestive enzymes by exocrine cells
secretion of hormones by endocrine cells
regulate digestion
Stomach
chemical breakdown of food by acid and enzymes
mechanical breakdown via muscular contractions.
gallbladder
storage and concentration of bile
large intestine
dehydration and compaction of indigestible materials for elimination
resorption of H2O and electrolytes
host defense
small intestine
enzymatic digestion and absorption of H2O, organic substrates, vitamins, and ions
host defense
duodenum, jujenum, ileum
Sphincters
upper and lower esophageal sphincters pylorus: between stomach and duodenum Sphincter of Oddi: between pancreas and SI ileocecal valve: SI and LI internal and external anal sphincters
musculature of GI
out to in
- serosa
- longitudinal muscle layer
- circular muscle layer
- submucosa
- mucosa
GI lined with
simple columnar epithelium with millions of gastric glands that extend into mucosa
Glands have specialized cells
Specialized cells of GI glands
chief cells
parietal cells
mucous cells
gastrin
chief cells
pepsinogen; inactive pepsin
parietal cells
hydrochloric acid
intrinsic factor
mucous cells
produce layer of alkaline mucus to sheild stomach wall
gastrin
microvili that monitor pH
Neural control
CNS: autonomic Intrinsic nervous system - 2 layers -- myenteric -- meissner PSNS and SNS
myenteric (auerbach) plexus
Neural control
between longitudinal and circular muscles
muscle movement
PSNS stimulation -> inc. activity.
- tonic contraction of intestinal wall inc.
- rhythmic contractions inc. in intensity and rate
- velocity of conduction inc.
SNS stimulation -> dec. activity
Meissner (submucosal)
Neural control lies in submucosa controls secretions sensory functions - gut epithelium - stretch sensors
myogenic
origin of phasic and tonic contractions
smooth muscle
interstitial cells of cajal
myogenic control
propagation of slow waves in ICC network
spontaneous activation of pacemaker
-> conduction of slow waves
-> depolarization and activation of Ca channels
Neural input to ICC conducts to smooth muscle and regulates responses to slow wavesGI
GI thresholds
threshold for contraction
Electrical threshold
- leads to “spikes” or action potentials
long reflex
stimulus -> chemoreceptor/osmoreceptor/mechanoreceptor -> CNS -> back to local enteric nerve plexus -> effectors (SMC or gland) -> response
short reflex
stimulus -> chemoreceptor/osmoreceptors/mechanoreceptor -> local enteric nerve plexus -> effectors -> response
chemical control liver
insulin like GF: somatomedin
angiotensinogen/ angiotensin
thrombopoietin
chemical control duodenum
secretin
cholecystokinin
chemical control kidney
renin
EPO
calcitriol
thrombopoietin
chemical control stomach
gastrin ghrelin neuropeptie Y somatostatin histamine endothelin
chemical control pancreas
insulin
glucagon
somatostatin
pancreatic polypeptide
gastrin
secreted in response to food entry
- inc. motility
- mediator of gastric acid secretion
- constrict LES: prevent reflux
cholecystokinin
secreted in response to fatty substances
-> galbladder contractility inc. -> bile secretion
Stimulates pancreatic secretion
-> regulate gastric emptying, bowel motility
secretin
in response to entry of acidic gastric juice
-> pancreatic fluid and bicarb secretion
Ghrelin
peptide:
inc. appetite
stimulates GH
produces wt gain
helps regulate mealtime hunger
arterial blood flow
aorta
- Celiac artery
- hepatic artery: liver
- gastric artery: stomach
- splenic artery: spleen, pancreas
- Superior mesenteric artery: SI, pancreas
- Inferior mesenteric artery: LI
Venous blood flow
All GI organs -> portal vein
-> liver -> hepatic vein -> inferior vena cava
