Physiology/Function

Question 1

What are the three general roles of the large intestines?

Answer 1

(Water/ion absorption, storage of feces, and in hindgut fermenters, digestion)

Question 2

How does the presence of pressure or chemical irritation in the ileum versus the cecum affect the ileocolic or ileocecal orifice?

Answer 2

(If there is pressure in the ileum, it opens the orifice and if there is pressure in the cecum, it closes the orifice)

Question 3

What is the purpose of antiperistalsis in the large intestines?

Answer 3

(More mixing and more time for absorption primarily of water)

Question 4

What two processes are triggered by the presence of material in the rectum?

Answer 4

(The relaxation of the internal anal sphincter and the increase of propulsive movement)

Question 5

The sodium-potassium pump moves sodium which then allows what other electrolyte and water to follow?

Answer 5

(Chloride)

Question 6

What is the primary mechanism by which potassium is absorbed?

Answer 6

(Sodium-potassium pump pumps potassium into cells which means the intercellular space has very little potassium so it can then passively diffuse down the gradient into the intercellular space to then be absorbed)

Question 7

(T/F) There is no enzymatic activity/digestion in the colon of any species

Answer 7

(F, no endogenous but definitely microbial)

Question 8

What does lignin block from reaching cellulose, hemicellulose, and pectin within the cell wall?

Answer 8

(Cellulase)

Question 9

Would a younger, cool-weather plant have more or less lignin than an older, warm-weather plant?

Answer 9

(Less)

Question 10

What are the products of cellulase action on hemicellulose, cellulose, and pectin?

Answer 10

(Oligo- and monosaccharides)

Question 11

Microbes use oligo- and monosaccharides through their glycolytic pathway and produce what byproduct?

Answer 11

(Volatile fatty acids)

Question 12

Where within the GIT is protein absorbed in horses?

Answer 12

(Small intestine)

Question 13

(T/F) Horses do not utilize microbial protein and it is instead passed out in the feces.

Answer 13

(T)

Question 14

(T/F) A majority of the fermentation that occurs in a horse’s GIT occurs in the cecum.

Answer 14

(F, ascending colon)

Question 15

Where does propulsive movement in the ventral colon of horses originate?

Answer 15

(Near the cecum)

Question 16

Where does retropulsive movement in the ventral colon of horses originate?

Answer 16

(Pelvic flexure)

Question 17

Where does retropulsive movement in the dorsal colon of horses originate?

Answer 17

(Distal right dorsal colon)

Question 18

There are multiple possible sites for large colon impaction in horses but one more commonly becomes impacted when compared to the others, what site is that?

Answer 18

(Pelvic flexure)

Question 19

Why is the pelvic flexure the most common site for intestinal impaction in horses? Three answers.

Answer 19

(Food has to fight gravity, it is much narrower, and it is the location of a pacemaker which shuts down when there is GI wall distention)

Question 20

Where is a large quantity of bicarbonate and phosphate secreted to buffer the content of the hindgut fermentation sites?

Answer 20

(Ileum)

Question 21

Do foregut or hindgut fermenters have an advantage when they are eating poor-quality feed?

Answer 21

(Hindgut)

Question 22

Do foregut or hindgut fermenters have an advantage when they have scarce feed?

Answer 22

(Foregut)