Final Exam GI Physiology: Equine Digestion Flashcards
What is the most prominent feature of Equine digestion?
Fermentation in the Cecum and Large Colon
What is “Back” Fermentation?
Fermentation that occurs in the cecum and large colon, typical of equine animals
What are the fermentation products of equine digestion?
Acetate, Propionate, and Butyrate
VFAs provide what % of a horse’s daily energy requirement?
Up to 75%
VFAs provide what % of a horse’s daily energy requirement? What about a cow?
Horse: 75% DER through VFAs
Cow: 70% DER through VFAs
What is the origin of water found at the site of fermentation?
The cecum and colon is the origin of the water
Microbes hydrolyze cellulose into ______ .
Monomers
Cecal and Colonic lumen osmolality is dramatically increased by the hydrolysis reaction of what?
Cellulose into Monomers
What are produced monomers converted into?
Monomers are converted into 2-3 VFAs
What is the overall effect of increasing osmolality in the cecal and colonic lumen?
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.
What % of body weight is extracellular water?
20%
How many times per day is the entire plasma volume secreted and absorbed across cecal and colonic mucosa in a horse?
5 TIMES PER DAY!
The movement of such large volumes of water across cecal and colonic mucosa causes increases in what 2 plasma components?
Renin and Aldosterone
Which is more acidic? The equine hindgut or the rumen?
The rumen is more acidic
In which species is microbial protein utilized? Why?
The cow.
There are no Na+peptide or Na+amino acid symports past the small intestine in the horse.
What are prominent features of the large intestine in regards to equine colon motility?
Mass Movement
Segmentation
Peristalsis
Antiperistalsis
Where is segmentation most prominent?
In the Cecum
Mass movements propel cecal contents from the ileum, into where?
Right Ventral Colon receives cecal contents via mass movements
Peristalsis propels cecal contents where?
Along the right and left ventral colons
What feature of the large intestine promotes retention of ingesta in the ventral colon?
Antiperistalsis at the pelvic flexure
The ventral colon is a major site of ______ absorption.
VFA
PSNS Neurotransmitters are important in coordinating what activities?
Peristalsis and antiperistalsis at the pelvic flexure
Where does impaction occur most frequently in a horse?
The pelvic flexure!
What effect does SNS innervation and opioids have on equine motility?
Inhibition of motility
