GI: Secretions of the Gastrointestinal Tract II Flashcards
Describe the secretory functions of the small intestine
Brunner’s glands secrete mucous and are in first few cm of duodenum. Crypts of Liberkuhn secretes mucous and water/ions and are in the entire length of the small intestine. It has an endocrine function> CCK, released from I-cells, we’ve talked about these… stimulates gall bladder to release bile.
Describe the motor, secretory and absorptive functions of the large intestine.
Has crypts but no villi and does not secrete enzymes. Crypts secrete alkaline mucous, protects wall of intestines and adheres fecal material. Secretion is stimulated by PNS, tactile stimulation, ENS and mucousal irritation.
List the major pancreatic digestive enzymes and their substrates.
Endocrine: islets - insulin, glucagon, and somatostatin. Exocrine: acini, ducts…
Enzymes that digests carbohydrates: pancreatic amylase (breaks down starches into disaccharides). For protein digestion: trypsin, chymotrypsin **These two mentioned first are endopeptidases, and carboxypeptidase **which is an exopeptidase - cuts off one at a time. For fat digestion: pacreatic lipase, phospholipase, and cholesterol esterase.
Describe the non-enzymatic portion of pancreatic exocrine secretion and its function.
The pancreas also has to be careful about not digesting itself… keeps enzymes from activating each other. Enzymes that activate are enterokinase and trypsin. We also have trypsin inhibitor.
Describe the control of pancreatic exocrine secretion.
Regulated by acid entering the duodenum. Makes bicarb to buffer acid there.
Mediated by vagus nerve: the cephalic and gastric phases. Then intestinal secretion.
List the important constituents of bile and their functions, particularly bile acids. Describe enterohepatic circulation of bile salts and explain its diagnostic significance.
Bile salts are made in the liver, and stored in the gall bladder…bile salts enter duodenum and then enters the blood srtream and is basically recycled: enterohepatic circulation. Oatmeal binds to bile salts but interrupts the recycling process. Soluble fiber is important for this, high cholesterol. Fiber is undigestible carbohydrate.
