3b Digestive Physiology of Horses Flashcards Preview

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Flashcards in 3b Digestive Physiology of Horses Deck (32):
1

What is the role of the GI tract?

- digestion and absorption
- microbiome
- immunity
- secretions and excretion

2

Horses have a similar GI anatomy compared to which animal?

pig

3

How much the the horse GI tract weigh?

- 500kg

4

How long is the SI?

20-24m

5

How long is the LI?

9-10m

6

How does horse absorb microbial protein?

- some essential amino acid absorption occurs in handgun

7

What macronutrient is the horse best adapted for to utilize?

- fibre

8

What is the purpose of saliva?

- secretion stimulated by mastication
- contains small amount of bicarbonate
- provides buffer against stomach acid

9

How many teeth do horses have?

- 36
- 12 incisors, 12 premolars, 12 molars

10

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)

11

Where can microbial fermentation occur in the stomach?

- oesophageal and fundic region

12

What is the emptying time of the horse compared to dogs and cats?

- horse 120 min
- dog 5-10 hours
- cat 3-6 hours

13

What is the function of the exocrine pancreas?

- secretes enzymes and bicarbonate salts into the gut
- enzymes: inactive proteases, lipases and amylases

14

What is the function of the endocrine pancreas?

- secrete hormones into blood
- hormones: insulin, glucagon

15

What is the function of the liver?

- produce bile which drains into SI to emulsify fat
- NO GALL BLADDER

16

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

17

Describe the caecum.

- very large (1m, 25-35L capacity)
- microbial population
- responsible for microbial synthesis of SCFA and protein

18

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

19

How do small and large intestinal histology differ?

- large intestine contains no villi and deeper crypts

20

What are the ways the intestine increases capacity?

- coiling
- folds
- villi
- microvilli

21

What are the enzymes involved in protein digestion and where do they originate

- stomach: pepsin
- pancreas: trypsin, chymotrypsin, elastase, carboxypeptidase
- intestine: aminopeptidases, dipeptidases, tripeptidases

22

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

23

How are AA transported?

- different transport systems based on AA classification
- most AA transport is active transport

24

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)

25

How are carbs absorbed?

- sodium dependent transporter
- some diffusion, mostly active transport

26

What enzyme digests fat?

- lipase from pancreas
- breaks down triglycerides into free fatty acids and monoglycerides

27

How are fats absorbed?

- lymph

28

In what order are SCFAs absorbed in the large intestine?

acetate > propionate > butyrate

29

How much energy do horses acquire from SCFA?

50-70%

30

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

31

What are the 3 ways in which SCFA are absorbed?

- passive
- facilitated
- symporter

32

How do SCFA interact with the pancreas?

- provide signals to islets which regulate insulin release