Lower GI II Flashcards
(24 cards)
Where does digestion of carbs begin?
mouth
What is the role of amylase?
to hydrolyze starch to form sugars
What secretes amylase?
pancreas
Where are disaccharides broken down into monosaccharides?
brush border of the small intestine, monosaccharides absorbed by enterocytes involving SGLT-1
Where does digestion of proteins begin?
stomach
What does pepsin require to be activated from pepsinogen?
acidic environment
Action of pepsin
hydrolyzes proteins to peptides
Where does polypeptide breakdown occur?
small intestine
What initiates the activation of proteolytic enzymes?
enteropeptidase (enterokinase) secreted by duodenal enterocytes
What enzymes secreted in the pancreas are involved in polypeptide breakdown?
trypsin, chymotrypsin, elastase, carboxypeptidase, and amylase
Where does further breakdown of oligopeptides to amino acids occur?
intestinal brush border
Where does digestion of lipids begin?
small intestine
How to lipids enter the small intestine?
as triglyceride droplets
What enzymes are involved in lipid digestion?
pancreatic lipase, pancreatic lipid esterase
What role to micelles play in lipid digestion?
the FA and glycerol released from the TAG breakdown combine with bile salts to form micelles which transport (FA, monoglycerides, glycerol, phospholipids, cholesterol, vit A, K) and are passively absorbed across enterocyte apical plasma membrane into the blood.
What role to chylomicrons play in lipid digestion?
TAGs recombine w/ proteins to form chylomicrons which are enclosed w/i membranes in Golgi apparatus and allow for excytosis. Chylomicrons are taken up by lacteals and will later enter the blood.
Cholecystokinin site of secretion
upper intestinal mucosa (duodenum); secreted in response to gastric contents
Cholecystokinin targets and effects
pyloric sphincter to slow stomach emptying; stimulates bile release from gallbladder; stimulates secretion of pancreatic enzymes; competitive inhibitor of gastrins
Gastrin site of secretion
Pyloric-antral portion of stomach
Gastrin Targets and effects
Stimulates HCL production by gastric parietal cells
Promotes growth of gastric mucosa
Stimulates gastric motility
Stimulates release of insulin by pancreatic beta cells
Secretin site of secretion
Epithelial cells of duodenum - stimulated by acid contents of stomch
Secretin targets and effects
enhances release of insulin by pancreatic beta cells
stimulates bicarb secretion by pancreas
Epithelium of the anus
stratified squamous epithelium
Skeletal muscle in anal canal
anal sphincter
