Lower GI II Flashcards
(24 cards)
What is the role of amylase?
hydrolyze starches to form sugars.
starch—-> disaccharides
Where are disaccharides broken down into monosaccharides?
brush border of the small intestine and monosaccharides are absorbed by enterocytes
Describe the sequential breakdown of proteins into amino acids; where do each of the steps occur?
Where does lipid digestion begin. What enzymes are involved? what role do micelles and chylomicrons play?
For cholecystokinin, secretin, and gastrin, give the site of secretion, targets, and effects.
What organ produces bile salts?
the liver (not the gall bladder)
Where does lipid digestion begin?
in the small intestine.
Lipids enter as triglyceride droplets.
What is the function of pancreatic lipase?
emulsify large lipid droplets into smaller droplets and release fatty acids and glycerol
What molecules can micelles transport?
fatty acids, monoglycerides, glycerol, phospholipids, cholesterol and vitamin K and A.
What cells of the small intestine absorbs the micelles?
apical plasma membrane of enterocytes in the small intestine and requires fatty acid binding proteins (FABPs)
Where does carbohydrate digestion begin?
in the mouth
What secretes cholecystokinin?
upper intestinal mucosa (duodenum)
A response to what initiates cholecystokinin secretion?
secreted in response to gastric contents
What are the 4 actions of cholecystokinin?
1) pyloric sphincter to slow down emptying of stomach
2) stimulates bile release from gall bladder
3) stimulates secretion of pancreatic enzymes
4) competitive inhibitor of gastrins\
What secretes secretin?
epithelial cells of duodenum
What stimulates secretion of secretin?
stimulated by acid contents of stomach
What are the actions of secretin?
- enhances release of insulin by beta pancreatic cells
- stimulates bicarbonate secretion by pancreas
What secretes gastrin?
pyloric-antral portion of stomach
What are the actions of gastrin?
- stimulates HCl production by gastric parietal cells
- promotes growth of gastric mucosa
- stimulates gastric motility
- stimulates release of insulin by pancreatic beta cells.
What type of epithelium lines the anal canal?
stratified squamous epithelium
What type of muscle is the external anal sphincter?
skeletal muscle
What type of epithelium lines the rectum?
simple columnar
What type of muscle is the internal anal sphincter?
smooth muscle
What marks the transition from the embryonic mesoderm to embryonic ectoderm in the anus?
pectinate line
