Digestive System 1B Flashcards
what gets absorbed in the stomach
small, non polar substances like lipid-soluble alcohol and aspirin
what is intrinsic factor
substance made and released by the parietal cells in the stomach
required for the absorption of vitamin B12
lack of it causes pernicious anemia
where is B12 absorbed and what is it important for
ileum of the small intestine
maturation of red blood cells
what are the four regions of the stomach
cardia
fundus
body
pylorus
what are some features of the cardia of the stomach
portion right below the esophagus at the cardiac orifice
cardiac orifice has inferior esophageal sphincter
what are some features of the pylorus
opens into the duodenum at the pyloric orifice
pylorus is surrounded by pyloric sphincter
what are the purpose of rugae in the stomach
folds that allow the stomach to expand (only seen when stomach is not stretched)
what is the stress-relaxation response in the stomach
when the stomach stretches, it initially contracts
after a while of being stretched however, it will relax
allows us to keep eating
what are the two serous membranes of the stomach
greater and lesser omentum
what are some features of the greater omentum
extends inferiorly from the greater curvature of the stomach and drapes over the intestine, spleen, and transverse colon
has fat deposits and lymph nodes
what are some features of the lesser omentum
extends superiorly from the lesser curvature of the stomach and duodenum to attach them to the liver
what is significant about the inner lining of the stomach
mucosa - simple columnar epithelium which are replaced often due to the acid
lots of gastric pits
gastric glands which help expels secretions when it contracts
what are the three layers of the muscularis of the stomach and what are their function
inner oblique, middle circular, and outer longitudinal
oblique helps with churning and blending
all do mechanical digestion
where are the 5 types of glands found in your stomach
1.) surface mucous cells
2.) mucous neck cells
3.) parietal cells
4.) chief cells
5.) G-cells
what do surface mucous cells do
most superifical cell that lines stomach and gastric pits
secrete alkaline product containing mucin
mucous protects from ulcers and abrasions
what do mucous neck cells do
deep to surface mucous cells
deep to base of gastric pit
found among parietal cells
produce acidic mucin to help maintain acidic conditions
what are the two secretions of parietal cells
intrinsic factor and hydrochloric acid components
what does hydrochloric acid do
responsible for low pH of stomach
components (H+ and Cl-) secreted by parietal cell
explain how hydrochloric acid is formed from parietal cells
1.) CO2 from the stomach lumen and H2O from the parietal cell combine to form carbonic acid (catalyzed by carbonic anhydrase)
carbonic acid dissociates into H+ and bicarbonate
H+ is pumped into lumen of the stomach by hydrogen/potassium pump
2.) bicarbonate is transported out of the parietal cell into the blood
chloride is transported into the cell then the lumen of the gastric gland (chloride shift)
chloride is pumped into the stomach lumen
3.) chloride forms with hydrogen to form hydrochloric acid
what are the 5 things that the low pH created by HCl facilitates in the stomach
1.) food breakdown
2.) protein denaturation
3.) pepsin activation
4.) enhanced enzymatic activity
5.) protection
explain pepsin activation
pepsinogen from chief cells is converted to pepsin
explain enhanced enzymatic activity of the stomach
hydrochloric acid creates optimal pH environment for enzymatic activity of both pepsin and acidic lipases
explain protection of the stomach
low pH protects us against infectious agents
what are some features of chief cells of the stomach
most numeous secretory cells, 4th layer deep
produce and secrete zymogen granules and gastric lipase
