Lecture 20 - colon (freeman) Flashcards Preview

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Flashcards in Lecture 20 - colon (freeman) Deck (12)
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1
Q

microbial digestion - perfect environmental conditions

A
availability of substrate
prolonged rentention time
anaerobic conditions
continuous buffering
hydration of contents
2
Q

colon motility

A

prolonged retention time
propulsion and retropulsion
pacemaker in pelvic flexure

3
Q

neutralization of contents

A

high Cl and low bicarb concentration in pancreatic fluid and intestinal fluid

4
Q

how are contents neutralized in ileum and distal jejunum?

A

Cl/HCOe exchange

Cl may provide a source for exhange of bicarb for neutrailization later in the cecum

5
Q

large intestine function

A

absorb large volumes of water, Na and bicarb in response to a cyclic pattern of microbial digestion

95% of Na, bicarb and water in large intestine is reabsorbed daily

6
Q

cecum function

A

water conservation

7
Q

distal colon function

A

conserve sodium and water retained earlier for microbial ferementation

8
Q

a high fiber diet will need…

A

more water for microbial fermentation/buffering

9
Q

ion transport: Na absorption in proximal colon

A

electoneutral exchange with H

10
Q

ion transport: Na absorption in distal colon

A

aldosterone-controlled (Na/K exchange - Na out, K in)

11
Q

enterosystemic cycle

A

a process that conserves water lost in digestive secretions

important when:

  1. feeding practices alter “normal grazing” patterns (like horses being fed twice a day)
  2. animals with diarrhea
12
Q

horses and enterosystemic cycle

A

horses are continuous grazers and consume hi fiber diets - large ECF volumes are drawn into colon daily and need to be replaced.

horses fed in ways that deviate from normal grazing –> plasma volume can decrease by 15%! –> result: hypovolemia (shock)

decrease in ECF –> hypovolemia –> activates renin-angiotensin-aldosterone system –> Increase renin –> increase angiotensin –> increase aldosterone –> aldosertone secretion can increase colonic and kidney reabsorption of Na and water –> dehydrating components to point of impaction and colic!

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