Exam 3 – Dr. Lunsford Intestinal Secretion and Absorption and Emesis Flashcards
Describe the mechanism of water secretion
Enterocytes lining the crypts actively secrete chloride ions
The chloride ions go through channels called the cystic fibrosis transmembrane conductance regulator (CFTR)
The cells also actively secrete bicarbonate ions
Chloride and bicarb cause the “electric drag” to draw sodium into the lumen
Water then follows by osmosis
What is the turnover for villus with digestive enzymes in enterocytes like?
Done by crypt stem cells
Approximately 5 days
How is water transported in the small intestine?
By diffusion
What happens to water when chyme is dilute?
It is absorbed
What happens to water when chyme is concentrated?
It is diffused back
What is chyme?
Maintained isomolar to the plasma
What causes sodium absorption?
Aldosterone
What causes the release of aldosterone?
Dehydration
What is aldosterone and sodium absorption particularly important in?
Large intestine
What happens when absorptive capacity is surpassed?
Diarrhea
What is the absorptive capacity in humans?
5 to 8 liters
What is emesis triggered by?
Local GI irritants signaling the vomiting center
Chemicals or drugs binding to the chemoreceptor trigger zone
