Rabbit GI anatomy and physiology Flashcards
Name the rabbit salivary glands (and if you upgrade to PRO, add a picture to label)
Sublingual
buccal
Parotid
mandibular
What percentage of the GIT volume is the stomach?
15%
What does the ampulla (just past the pylorus) do?
AKA ampulla of Vater. It’s where the pancreatic/common bile ducts empty.
what is the sphincter of Oddi?
muscle that controls secretion from the pancreatic/common bile ducts into the ampulla
How fast do rabbit incisors grow?
up to 2 mm/wk
Basic function of the colon?
separates first-pass fibers into nondigestible (to be pooped out) and digestible (to stay as a substrate for fermentation, mostly in the cecum. also reabsorbs water and makes poop.
Do rabbits see their food as they eat it?
nope, they select food & textures via vibrissae & taste etc. Prey eyes.
How many teeth do rabbits have and what are they for?
28 total
6 incisors (2 real upper, 2 peg teeth upper, 2 lower): to slice food
22 PM/Ms: grind the food.
what are normal pH ranges in rabbits
Pre-weaning: 5.0-6.5 (helps establish flora)
Post weaning, eating first pass food: 1.0-2.0 (Jesus)
Post weaning, eating a cecotrope: 3.0
Normal GI transit time in a rabbit?
3-6 hours for first pass
Main function of duodenum?
Mix in bicarb and digestive enzymes (esp to cecotropes)
Main functions of jejunum & ileum?
Actual absorption of nutrients from the cecotrophs; some bacterial fermentation occurs in the ileum as well.
What’s the thingy between the ileum and the colon?
ileocolic valve - reduces reflux from lower GIT to upper
General transit time of the small intestines?
10-20 min in jejunum, 30-60 min in ileum
Where are the gut-associated lymphoid tissues found in rabbits?
Peyer’s patches (Jejunum & distal ileum)
Sacculus rotundus at the ICJ
Vermiform appendix (distal cecum)
Lymphoid follicles along the colon
which organ makes up 49% (but not 50%, that would apparently be way too much) of the GIT volume
seekum you shall findum
but takes up >50% of abdominal volume. how the hell does that math work either??
Twisty coils on the right side, huge, thin walled
Is a cecum!
what’s at the end of the cecal rainbow?
The vermiform appendix (secretes bicarb and makes immune cells)
What are the 4 regions of the rabbit colon?
1) Anterior part 1: about 10 cm. 3 taeniae, 3 haustrae
2) Anterior 2: about 20 cm. 1 ea taenia/haustra
3) Fusus coli
4) Distal colon: 80-100 cm long, no t/h, short crypts, many goblet cells
what’s the function of the fusus coli and where is it
3rd region of the rabbit colon, 4 cm band of muscle & innervation, controls pass-through of multiple areas of large intestine. Lots of goblet cells, which package up cecotrophs in mucus and squish them down.
describe how particles move through the cecum and colon (ideally with picture/Pro)
homogenous first-pass schmoo goes from ileum and get spread evently between cecum and colon. Cecum moves stuff over to the colon, which divides it into save vs poop. Save gets refluxed to the cecum to ferment. Cecum has different contractions for cecotrope vs excrete.
what plant fibers can the cecal microbes ferment?
mostly cellulose, pectin, and hemicellulose; last 2 are more important
what are the main products of cecal fermentation and where do they go?
volatile fatty acids - 75% acetate, 10% propionate, 15% butyrate.
Butyrate: feeds the colon
Others: bloodstream, go to liver & get made into other things there.
Overall this is 30% of the rabbit’s metabolic needs!
How does the fusus coli affect cecotropes?
1) secretes prostaglandins to STOP haustral contractions and START distal cecal contractions
2) cecotrope goes FWOOSH down the cecum, prox colon
3) Fusus coli goblet cells package it in mucus and squish it into shape
4) Colon goes PEW PEW PEW
What is the percentage makeup of a cecotrope?
By weight: 34% Dry matter, 66 % water
Dry matter subdivides into 18% fiber, 30% protein, and 52% PURE MAGIC
The protein subdivides into 80% microbial origin, 20% directly from food
What nutrients does a cecotrope contain?
Amino acids - especially lysine, threonine, and the sulfur-containing AAs B vitamins (lots of them) Vitamin K Various minerals, potassium etc Magic
3 broad categories of small intestinal motility regulators (endogenous):
- Autonomic nervous system
- “hormones”
- Nutritional content of food, esp indigestible fiber
What is a motilin, where does it come from, and why did its parents not raise it right
chemical (hormone?) released from endocrine M cells in the mucosa of the duodenum and jejunum.
where are motilin receptors found?
All small intestines
Colon and rectum but NOT cecum
CNS
What do motilin receptors actually do?
trigger “migrating motor complexes” that push peristaltic waves along. (everywhere but the cecum)
What can pretend to be a motilin?
erythromycin or a bunch of crap with no name
NOT any of the commonly used prokinetics - those are mostly dopamine or 5HT receptor agonists
Rabbit feces is made during what?
mostly while eating
Cecotropes are made when?
usually a few hours later, while resting
How fast are cecal contractions, usually; and what do they do?
1-2 per minute; they mix up the fermenty stuff and keep it cooking.
What kinds of contractions does the colon undergo? (there are 3 big ones)
1) Shallow, aboral, of haustra (14-16 per minute) - separating fibers
2) Occasional ORAD in single-haustra zone - refluxes usable things to cecum
3) Migrating segmental contractions to push out poop
Will high protein in the diet increase or decrease cecotrophy?
Decrease it
How does excess protein lead to dysbiosis?
Excess dietary protein elevates plasma urea AND CECAL AMMONIA CONTENT; this raises the pH and allows overgrowth of Clostridia and E. coli among others.
Increased dietary carbs are most likely to cause enteritis in which age group?
young rabbits - more starch makes it to the ileum with them, and it will have a higher effect on the intestine. In other age groups, if they eat enough fiber, the carb content matters slightly less. (This is probably why a rabbit who eats a good diet can tolerate fruit more than one fed a shitty diet).
fiber & protein differences between first and second cut hay?
First cut - usually higher in fiber, lower protein
Second cut - usually more protein & softer
Normal water intake for pet rabbits?
will depend greatly on diet & amt fresh greens, but est 120 ml/kg upper end
