Digestive Physiology 1

Question 1

What are the structures to increase surface area to capacity in the GIT?

Answer 1

1. Villi
2. Microvilli
3. Coils
4. Folds

Question 2

What macronutrient does the dog / cat have the LOWEST ability to digest?

Answer 2

Fiber - need microbes in the gut

Question 3

What kind of diet does a dog have? Cat

Answer 3

Omnivorous, carnivorous

Question 4

What are the four pairs of salivary glands

Answer 4

parotid, sublingual, zygomatic, mandibular

Question 5

What stimulates the salivary glands to secrete saliva?

Answer 5

Presence / smell of food

The type of food and it’s moisture content affect saliva amount and composition

Question 6

What do dogs and cats lack in their saliva? What is a consequence of this?

Answer 6

Alpha amylase - lack the ability to start starch digestion in the mouth. Also may hinder the ability to detect glycemic index in food.

Question 7

What features are prominant in dog teeth

Answer 7

lots of molars / pre molars to grind / chew large pieces of food

Question 8

What features are prominant in cat teeth

Answer 8

Teeth are suited for holding prey, less suited towards grinding

Question 9

What is secreted in the stomach and what is digested there

Answer 9

HCL and pepsinogen - where protein digestion starts (becomes unfolded due to acidity)
NO carbohydrate or fat digestion in the stomach just carbs

Question 10

Why are dogs able to eat large discrete meals?

Answer 10

Proximal part of the stomach can expand

Question 11

What is gastric secretion in the stomach influenced by

Answer 11

Amount of protein in the meal, meal volume, hormones

Question 12

What affects gastric emptying rate?

Answer 12

Diet composition ( more dense fibers take longer to pass though, decrease passage rate), stomach volume, water intake, body weight
High density particles empty more slowly than smaller sized particles
Hormonal control based on macronutrient composition and characteristics

Question 13

Name some exocrine functions of the pancreas

Answer 13

Secretes enzymes, and bicarbonate salts into the gut to establish ph
for example, trypsin, chymotrypsin, inactive enzymes (proenzymes), lipases, amylases, proteases

Question 14

Endocrine functions of the pancreas?

Answer 14

Secrete insulin / glucagon

Question 15

What is the role of bile, where is it stored / produced

Answer 15

Produced in the liver, stored in the gall bladder, it emulsifies fat and activates enzymes to digest fats

Question 16

How can transit time be measured?

Answer 16

Via indigestible markers

Question 17

Name some differences in SI between cat and dog

Answer 17

CAT: sugar transport system NOT adaptive to varying levels of dietary carbohydrate
Dog: sugar transport systems are HIGHLY adaptable to varying levels of dietary carbohydrates
Also with cats:
Free sugars and complex carbohydrates normally negligible percentage of diet
No energy wasting to change carrier systems
Pancreatic amylase production about 5% of that in dogs
Pancreatic amylase production is relatively nonadaptive in cats
Amino acid transporters are highly adaptable, esp. for arginine

Question 18

What are the main functions of the LI - how long is transit time approximately for dogs / cats?

Answer 18

absorption of water and electrolytes
Fermentation of dietary fiber and undigested nutrients from the SI
Transit time is about 12 hours

Question 19

What is excreted fecal material made up of

Answer 19

Endogenous sloughed cells, bacteria, undigested food, endogenous losses

Question 20

What does bacterial fermenation produce

Answer 20

SCFA, Lactate, CO2, Hydrogen gas (methane)

Question 21

What are incretins?

Answer 21

Incretin are gastrointestinal hormones- GIP that is glucose dependent insulinotropic peptide and GLP- glucagon like peptide-1 . After feeding GIP is released from K cells of small intestine whereas GLP-1 are released from L cells of large intestine. Both act on beta cells of pancreas and stimulates insulin secretion and this how intestine controls insulin secretion

Question 22

2 Incretins that are linked to fiber / starch

Answer 22

See intestine, section of pancreas, one incretin highlighted GLP-1 – an incretin (hormone produced) acts on certain amount of glucose in the lumen of the gut in SI food is degraded – think starch / glucose – taste receptors in gut (same as in mounth0 that recognize more glucose and secrete GLP – 1 which goes to the pancreas – which has receptors for GLP-1 (pancreas knows before glucose reaches it_) to start releasing insulin. Role – important signal molecule linking gut to pancreas. – not only nutrients that provide links to organs also hormones that provide link to hormones – part of system pancreas and gut communicate with each other.

Question 23

What is CCK where is it’s location of action

what is it’s primary action what’s it’s stimulus for secretion

Answer 23

Location of action: Duodenum / jejunum
Primary action: stimulates gallbladder contractions, pancreatic enzyme secretion. Inhibits gastric emptying and secretion / relaxation of the sphincter of odii
Stimulus for secretion is: peptides / AA / FA in the duodenum

Question 24

What is Gastrin where is it location of action what’s it’s primary action and what is its stimulus for secretion?

Answer 24

Location of action: Gastric antrum / duodenum
Primary action: Stimulates: secretion of gastric acid, pepsinogen and glucagon inhibits: gastric emptying
Stimulus for secretion: peptides / amino acids in the stomach, distension in the stomach