Exam 4: Lecture 60: Intestinal transport Flashcards
Why is it important to reabsorb secretions delivered to the proximal part of the SI?
The secretory fluids are a substantial part of the ECF volume
What are the main secretions from epithelial cells lining the intestinal crytps?
Fluid and electrolytes
Cl channels are located on which membrane of the epithelial cell of the crypt?
Apical membrane - facing the lumen
When do these Cl channels in the epithelial cells of crypts open?
In response to hormones and neurotransmitters binding to the basolateral membrane
A tight junction between enterocytes means what?
Fluid and ions move transcellulary
A leaky junction between enterocytes means what?
Fluid and ions move via paracellular route
T/F: The fluid absorbed is always isosmotic.
True
Which section of the SI is the major site for Na+ absorption?
Jejunum
In the jejunum, on the enterocyte apical membrane, which substance is brought into the cell via a Na+ co-transporter?
Monosaccharides or amino acids
In which portion of the SI is there an overall net absorption of NaCl?
Ileum
In the ileum on the enterocyte apical membrane, what molecule is being brought into the lumen via Cl- exchanger?
HCO3-
In the colon, Na+ and K+ channels are influenced by what hormone?
Aldosterone
In the colon under the presence of aldosterone, there is increased Na+ (absorption/secretion) and increased K+ (absorption/secretion)?
absorption; secretion
In cases of diarrhea, the. increased loss of K+ is due to what?
Increased flow rate of intestinal fluid
A large loss of volume of fluid from the GIT can ultimately cause what systemic issue?
Decreased BP
