Final Exam GI Physiology: Equine Digestion

Question 1

What is the most prominent feature of Equine digestion?

Answer 1

Fermentation in the Cecum and Large Colon

Question 2

What is “Back” Fermentation?

Answer 2

Fermentation that occurs in the cecum and large colon, typical of equine animals

Question 3

What are the fermentation products of equine digestion?

Answer 3

Acetate, Propionate, and Butyrate

Question 4

VFAs provide what % of a horse’s daily energy requirement?

Answer 4

Up to 75%

Question 5

VFAs provide what % of a horse’s daily energy requirement? What about a cow?

Answer 5

Horse: 75% DER through VFAs

Cow: 70% DER through VFAs

Question 6

What is the origin of water found at the site of fermentation?

Answer 6

The cecum and colon is the origin of the water

Question 7

Microbes hydrolyze cellulose into ______ .

Answer 7

Monomers

Question 8

Cecal and Colonic lumen osmolality is dramatically increased by the hydrolysis reaction of what?

Answer 8

Cellulose into Monomers

Question 9

What are produced monomers converted into?

Answer 9

Monomers are converted into 2-3 VFAs

Question 10

What is the overall effect of increasing osmolality in the cecal and colonic lumen?

Answer 10

To draw large volumes of water from mucosal cells and basolateral interstitium (so pretty much getting it from plasma) and put the water into the lumen of the cecum and colon.

Question 11

What % of body weight is extracellular water?

Answer 11

20%

Question 12

How many times per day is the entire plasma volume secreted and absorbed across cecal and colonic mucosa in a horse?

Answer 12

5 TIMES PER DAY!

Question 13

The movement of such large volumes of water across cecal and colonic mucosa causes increases in what 2 plasma components?

Answer 13

Renin and Aldosterone

Question 14

Which is more acidic? The equine hindgut or the rumen?

Answer 14

The rumen is more acidic

Question 15

In which species is microbial protein utilized? Why?

Answer 15

The cow.

There are no Na+peptide or Na+amino acid symports past the small intestine in the horse.

Question 16

What are prominent features of the large intestine in regards to equine colon motility?

Answer 16

Mass Movement
Segmentation
Peristalsis
Antiperistalsis

Question 17

Where is segmentation most prominent?

Answer 17

In the Cecum

Question 18

Mass movements propel cecal contents from the ileum, into where?

Answer 18

Right Ventral Colon receives cecal contents via mass movements

Question 19

Peristalsis propels cecal contents where?

Answer 19

Along the right and left ventral colons

Question 20

What feature of the large intestine promotes retention of ingesta in the ventral colon?

Answer 20

Antiperistalsis at the pelvic flexure

Question 21

The ventral colon is a major site of ______ absorption.

Answer 21

VFA

Question 22

PSNS Neurotransmitters are important in coordinating what activities?

Answer 22

Peristalsis and antiperistalsis at the pelvic flexure

Question 23

Where does impaction occur most frequently in a horse?

Answer 23

The pelvic flexure!

Question 24

What effect does SNS innervation and opioids have on equine motility?

Answer 24

Inhibition of motility