Final Exam GI Physiology: Small Intestine Flashcards
The small intestine produces three types of secretions. Name them.
Exocrine, Paracrine, and Endocrine
What do goblet cells secrete?
Mucin
What do crypt cells secrete?
Cl- followed by Na+, K+, and H20
Also secretes guanylin
Secretagogue neurotransmitters of the small intestine include…?
VIP and ACh
Guanylin
Why is guanylin unique?
It is an exocrine secretagogue which results in increased secretion
What does the toxin that many pathogenic enteric bacteria have developed do?
Stimulate the guanylin receptor which results in secretory diarrhea leading to death via hypovolemia, hypotension and shock
What does histamine do at the small intestine?
Increases secretory activity and is vasodilatory
What do prostaglandins do at the small intestine?
Increases secretory activity and is vasodilatory
What promotes the secretion of GIP?
glucose, fatty acids and monoacylglycerols
What does GIP do?
It’s an incretin and promotes the release of insulin
What does CCK do?
Promotes contraction of the gallbladder
Promotes pancreatic acinar secretion
Inhibits gastric motility
Inhibits HCl secretion
What stimuli promote the secretion of CCK?
Fatty acids, monoacylglycerols and AAs
What is known as “nature’s antacid”?
Secretin
What stimulates the release of secretin?
Luminal pH less than 3.5
What does secretin stimulate the release of?
Bile and pancreatic ductular cells
What does secretin inhibit?
Gastrin secretion
Gastric motility
Gastric emptying
T or F: Since secretin and CCK act to inhibit gastric emptying, both are important elements of the enterogastric reflex.
True
Where is gastrin produced?
By the G-cells in the mucosa
What does gastrin stimulate?
Gastric secretion
Closure of pyloric sphincter
Delays gastric emptying
What is GLP-1?
Glucagon-like peptide 1
What does GLP-1 do?
It is a potent incretin (along with GIP)
Where is GLP-1 secreted?
By mucosal cells of the ileum
What stimulates the release of GLP-1?
Food breakdown products
