Absorption by the Large Intestine/ Intestinal Secretion and Motility Flashcards
How many liters of water enters the colon each day?
2L
True or False? Nutrients are produced by the bacteria in the colon.
T
Overgrowth of bacteria can lead to:
the production of toxins that can lead to secretory diarrhea
Which epithelium is leaky, proximal or distal colon
proximal epithelium
True or False? The distal colon is leaky.
F
is the blood side of the colon positive of negative in relation to the lumen?
blood positive with respect of the he lumen
True or False? Equilibration happens in the distal colon.
F
ENac is only found in the:
distal tubule (tighte epithelium) and the distal colon, regulated by aldosterone. take up extra sodium, leads to low sodium in feces
Dominance of this exchanger in the distal colon:
Cl- bicarbonate exchanger, neutralize the acid created by the bacteria
What channel is responsible for neutralizing acid in the colon?
Cl-/ bicarbonate exchanger
Total number of flora in the intestines:
limited in duodenum and jejunum, rise in ileum and the large intestines
True or False? Most bacteria in the colon are aerobic.
F. Anaerobic. outnumber aerobes by 1,000-10,000:1
This toxin, produced by bacteria can cause secretion:
?
Bacterial population form the ileum on (number):
10^8/ml
Butyrate is a metabolite for these cells:
epithelial cells of the colon
What can happen if you have a lactase deficiency?
Organic ions that are osmotically active, can raise the osmolarity of the lumen. Low water concentration relative to interstitial fluid (400mOsm) leads to diarrhea
Why does fiber help relieve diarrhea?
bacteria act on cellulose that we can’t digest, raises the osmolarity of the lumen, which leads to diarrhea
Secretory diarrhea is aka:
Active Cl- secretion
Incubation period of cholera:
1-5 days
Where does the cholera toxin live?
small and large intestines
Mortality rate of untreated cholera:
50%, treated is 1-3%
Total body water volume:
40L, can lose 10L a day with cholera
How long does it take for cholera to run its course?
3-6 days
Turnover of in the intestinal epithelium (virus):
3-5 days, stem cells in crypt area divide and differentiate toe express transporters
True or False? Stem cell in the crypt have transporters.
F. Must differentiate first
What can lead to the destruction of crypt cells?
chemotherapy or radiation therapy, lots of fluid loss
What cells create the problem in secretory diarrhea?
crypt cells
True or False? The CFTR channels are almost always off in the basal state.
T. off or a very low state of on
To where does vibrio cholera stick?
brush border of epithelial cells, GM1 ganglioside receptor, sugar proteins in apical membrane, toxin breaks into p[arts, moves from basolateral to apical membrane, activate G coupled receptor that is already there and permanently turns on G protein complex, producing continuous supply of cAMP, which activate PKA, that activates the CFTR channel and Cl- leaks out
When will you stop having diarrhea with cholera?
the bacteria is washed out in the first day or two and you have to wait until all the initial infected cells are turned over (3-5 days) must keep the patient hydrated to survive those days
Treatment for kids with secretory diarrhea:
rice water, oral glucose is better treatment, glucose so provides substrate for sodium/ glucose cotransporter, can stimulate enough water absorption to offset the diarrhea
True or False? Very little K is lost in diarrhea.
F. lots of K is lost
3 types of diarrhea:
osmotic, secretory, and fast motility
Laxatives can work via these types of diarrhea:
osmotic or secretory
What problem occurs with fast motility?
not enough water reabsorption
how long does it take for food to get to the end of the ileum?
6-8 hours
How long does it take to shit out food?
24
Main function of segmentation:
mixing
Motility in the small intestines is based on:
slow wave contractility
How are short peristaltic contractions controlled?
controlled only by stretching of the wall of the small or large intestines, double reflex: contraction/ relaxation
What nerves control the short peristaltic contractions?
enteric nerves (VIP, NO, ATP)
Are short peristaltic contractions involved in short or long distance (movement) of bolus?
short
True or False? There is slow wave activity in the large intestines.
T
Frequency of slow wave in the large intestines:
3-5/ min
most effective propulsion of large masses of food:
mass peristalsis
Control of mass movement:
enteric nerves due to local distension, enteric nerves, anything related to eating
True or False? Opiates often cause diarrhea.
F. slow motility, cause constipation. Lomtil will do the same
How many anal sphincters?
2
True or False? The internal anal sphincter is what prevent the release of feces.
F. Relaxes more and more with pressure, external prevent defecation
What nerves control the anal sphincters?
enteric nerves, signal to external anal sphincter to contract and also telling the internal to relax, and a signal the urge to defecate
