Flashcards in 3b Digestive Physiology of Horses Deck (32):
What is the role of the GI tract?
- digestion and absorption
- secretions and excretion
Horses have a similar GI anatomy compared to which animal?
How much the the horse GI tract weigh?
How long is the SI?
How long is the LI?
How does horse absorb microbial protein?
- some essential amino acid absorption occurs in handgun
What macronutrient is the horse best adapted for to utilize?
What is the purpose of saliva?
- secretion stimulated by mastication
- contains small amount of bicarbonate
- provides buffer against stomach acid
How many teeth do horses have?
- 12 incisors, 12 premolars, 12 molars
What 3 regions is the stomach divided into? what do they do?
- oesophageal region (squamous epithelium)
- fundic region (glandular epithelium, parietal cells HCl, zymogen cells pepsin)
- pyloric region (glandular epithelium, gastrin)
Where can microbial fermentation occur in the stomach?
- oesophageal and fundic region
What is the emptying time of the horse compared to dogs and cats?
- horse 120 min
- dog 5-10 hours
- cat 3-6 hours
What is the function of the exocrine pancreas?
- secretes enzymes and bicarbonate salts into the gut
- enzymes: inactive proteases, lipases and amylases
What is the function of the endocrine pancreas?
- secrete hormones into blood
- hormones: insulin, glucagon
What is the function of the liver?
- produce bile which drains into SI to emulsify fat
- NO GALL BLADDER
Why the adaptive feature of missing a gall bladder?
- diet lower in fat so less need to large secretion of bile
- eat more frequently so don't need a collection organ
Describe the caecum.
- very large (1m, 25-35L capacity)
- microbial population
- responsible for microbial synthesis of SCFA and protein
Describe the large intestine of the horse.
- 4 large compartments and 3 major flexures
- right ventral colon (sternal flexure), left ventral colon (pelvic flexure), left dorsal colon (diaphragmatic flexure), right dorsal colon
- small colon ends in rectum
How do small and large intestinal histology differ?
- large intestine contains no villi and deeper crypts
What are the ways the intestine increases capacity?
What are the enzymes involved in protein digestion and where do they originate
- stomach: pepsin
- pancreas: trypsin, chymotrypsin, elastase, carboxypeptidase
- intestine: aminopeptidases, dipeptidases, tripeptidases
Why are di and tri peptides absorbed into enterocytes as well as single amino acids?
- more efficient as di and trip peptides take same amount of energy to absorb as single AA
How are AA transported?
- different transport systems based on AA classification
- most AA transport is active transport
What are the enzymes involved in carbohydrate digestion, where do they originate, what is their action?
- pancreas: a-amylase (starch)
- intestine: glucoamylase (alpha-limit dextrins), maltase (maltose), isomaltase (maltotriose), sucrase (sucrose)
How are carbs absorbed?
- sodium dependent transporter
- some diffusion, mostly active transport
What enzyme digests fat?
- lipase from pancreas
- breaks down triglycerides into free fatty acids and monoglycerides
How are fats absorbed?
In what order are SCFAs absorbed in the large intestine?
acetate > propionate > butyrate
How much energy do horses acquire from SCFA?
Why is a horse micro biome very sensitive to dietary change?
- micro biome needs to titrate
- dogs and cats rely less on micro biome and can adapt to large diet changes quicker
What are the 3 ways in which SCFA are absorbed?