Digestive Systems

Question 1

Define food

Answer 1

Food is a mixture of complex biochemical molecules to supply nutrients for maintenance and production.

Question 2

In what form are nutrients absorbed?

Answer 2

Nutrients are absorbed in the simplest molecular form.

Proteins digested to amino acids

Lipids digested to free fatty acids and glycerol

Complex CHO digested to oligo- or disaccharides

Oligo- Disacc digested to monosaccharides for absorption

Question 3

What are the functions of the digestive tract?

Answer 3

Ingestion

Digestion

Absorption

Metabolism

Assimilation (making it into final product)

Question 4

How does the animal facilitate digestion?

Answer 4

Physically - teeth (incisor, carnassial, molar)

Chemically- (hydrochloride acid in stomach)

Enzymatically- (enzymes in mouth, stomach, small intestine)

Question 5

Saliva production

Answer 5

Produced during eating (4 saliva glands)

Function = lubrication and act as a buffer

Saliva of cats, dogs and horses does not contain enzymes.

Question 6

What is the movement down the oesophagus from mouth to stomach called?

Answer 6

Peristalsis

Question 7

Gastric pits line the stomach, what do they secrete?

Answer 7

1. Mucus/bicarbonate
2. HCL (lowers pH to 2.0)
3. Pepsinogen (= a zymogen)
4. Gastrin

Question 8

What does hydrochloric acid in gastric stomach do?

Answer 8

Denatures and precipitates proteins.
Proteins broken down into smaller chain sizes (peptides) by an enzyme activated by HCL = pepsin
(Inactive from = pepsinogen)

HCL acid has an innate immune function as it denatures the protein of ingested micro-organisms and kills them.

Question 9

What are the 3 parts of the small intestine called?

Answer 9

Duodenum

Jejunum

Ileum

(No clear division)

Question 10

What are the 4 chambers of a cows stomach called?

Answer 10

Rumen

Reticulum

Omasum

Abomasum

(Distinct regions)

(180-230 litres in cows)
(20-45 litres in sheep)

Question 11

Describe the duodenum

Answer 11

First and shortest of the 3 sections.

Main site for enzymatic digestion as pancreatic and bile ducts enter here.

Question 12

Secretions

Answer 12

Intestinal wall (mucus, Maltese, sucrase, lactase, peptidase)

Pancreatic juice (trypsinogen and chymotrypsinogen, a-amylase, lipase)

Bile (bile salts, inc taurine salt)

Question 13

Where does absorption occur?

Answer 13

Absorption occurs along the entire digestive tract

Gastric stomach (alcohol, water & some drugs)

Small intestine (Jejunum, ileum) major site of nutrient absorption

Large intestine (water and VFA)

Question 14

Describe the Jejunum and ileum

Answer 14

Longest section of the small intestine

Vast surface area created by vili and micro vili

Plus fantastic blood supply and short diffusion distance —> absorption

Question 15

How do the majority of absorbed nutrients travel?

Answer 15

The hepatic portal vein to liver for metabolism

Fats are picked up by the lymphatic system (lacteals) and dumped into main blood system near heart.

Question 16

Large intestines

Answer 16

Comprised of caecum and colon.

Caecum has no known function in cats and dogs. But very Important in horses. Colon is much shorter in carnivores.

3 main functions.
-absorption of H2O and electrolytes
-storage of faeces
-fermentation of food residues.