ch 23 digestive system p2 Flashcards
cardia of stomach
portion leading right out of the esophagus
fundus of stomach
dome shaped portion of stomach on top
body of stomach
midportion of stomach
pyloric portion of stomach
inferior funnel shaped portion of stomach, leads right into small intestine, has the pyloric sphincter
pyloric sphincter
thick tissue controls release of food from stomach to intestine
omenta
mesenteries extending from greater and lesser curvature of stomach
lesser vs greater omentum
lesser is from liver to stomach and greater is stomach to intestines (its like a purse to hold intestines and spleen with many lymph nodes)
the autonomic innervation of stomach, parasympathetic vs symp
parasympathetic- via vagus nerve, increase digestion and muslce walls contract for rest and digest
sympathetic- decrease digestion, less stomach activity bc fight or flight thoracic splanchic nerves
stomach has 3 layers of muscle what n why
circular, longitudinal, oblique, allows each organ to have their own function
oblique muscle layer
provides extra muscle layer to generate force. stomach twists like a towel, shortens and widens. helps break down food by churning literally, moves the food and pummels Into smaller pieces to increase SA
mucosa of stomach has what
surface epithelia, simple columnar cells that secrete a lot of mucous with a basic pH
lining of the mucosa has what
gastric pits, which leads to gastric glands and secretes gastric juices.
mucous neck cell stomach
produces acidic and thin mucus, may protect other cells bc its more acidic
parietal cells stomach
secretes HCl and intrinsic factor
HCl makes it really acidic! 1.5-3.5
activates protein digestive pepsin which breaks down the plant cell walls
pepsin
breaks down plant cell walls and kills bacteria, activated with HCl starts the proteins digestion which denatures protein!!!
intrinsic factor stomach
necessary for vitamin B12 absorption in small intestine. B12 is a coenzyme for manny reactions such as ATP. also for erythropoiesis
chief cells stomach
produces pepsinogen, which is converted to pepsin, which as we know starts protein digestion in stomach
enteroendocrine cells of stomach
releases hormones, histamine and serotonin and somatostatin and gastrin!
histamine from enteroendocrine cells
stimulates parietal cells to release HCl
serotonin from enteroendocrine cells
stimulates contraction of muscle in stomach wall
somatostatin from enteroendocrine cells
slows gastric function, plays several inhibitory roles in stomach and other organs
gastrin from enteroendocrine cells
increases HCl secretion, stimulates contraction. of intestinal muscle, releases ileocecal valve, stimulates mass movement of materials
mucosal barrier of the stomach
protects stomach from its own gastric juice, bc low pH would corrode the stomach itself
the 3 mechanisms of protection for the stomach
thick alkaline mucus on internal surface of stomach (physical barrier), epithelial cells joined by tight junctions (ensures gastric juices can’t leave stomach), damaged epithelial cells are replaced fast (undifferentiated stem cells in gastric pits replace damaged cells, mitosis ensures that protection)