Alimentary system & Digestion

Question 1

List the functions of the digestive system

Answer 1

Ingestion, mastication, secretion, digestion, absorption, elimination, mixing, propulsion

Question 2

How is the digestive tract different from the digestive system?

Answer 2

The digestive tract is only the tube extending from the mouth to the anus.
The digestive system includes accessory organs as well.

Question 3

What are other names for the digestive tract?

Answer 3

Alimentary tract, alimentary canal

Question 4

What does the term ‘gastrointestinal tract’ technically refer to?

Answer 4

Only the stomach and the intestines, but is often a synonym for ‘digestive tract’

Question 5

Name the organs in the digestive tract, with their accessory organs

Answer 5

Oral cavity (salivary glands)
Phaynx (tonsils)
Oesophagus
Stomach
Small intestine (liver, gallbladder, pancreas)
Large intestine
Anus

Question 6

What are the two types of digestion?

Answer 6

Mechanical and chemical

Question 7

Mechanical digestion

Answer 7

Physical disruption of food into smaller parts

Question 8

Chemical digestion

Answer 8

Breakdown into small soluble constituents
Reliant on enzymatic action
Some enzymes are produced by the body, others are produced by commensal bacteria
Digestion carried out by commensal bacteria is referred to as fermentation

Question 9

Mechanical digestion in the oral cavity

Answer 9

Chewing / mastication

Physical break up of food

Question 10

Chemical digestion in the oral cavity

Answer 10

Saliva from salivary glands contains salivary amylase for carbohydrate digestion

Question 11

Name the three largest salivary glands

Answer 11

Parotid, Sublingual, Submandibular

Question 12

What’s the main function of salivary glands?

Answer 12

They make saliva, which is a combination of serous and mucous secretions from all the salivary glands

Question 13

What does the oesophagus do?

Answer 13

It transports food from the pharynx to the stomach

Question 14

The oesophagus is lined with stratified squamous epithelium – what function does it have?

Answer 14

It protects against mechanical abrasion

Question 15

What are the four main layers in the oesophagus wall?

Answer 15

Stratified squamous epithelium
Submucosa layer (with mucous glands)
Muscular layer (outer longitudinal muscle, inner circular muscle)
Adventitia

Question 16

Mechanical digestion in the stomach?

Answer 16

• Churning and mixing of food

* Increases contact between enzymes and digesta

Question 17

What gets released in the stomach to aid with chemical digestion?

Answer 17

• Pepsinogen
• Hydrochloric acid
• Rennin/Chymosin

Question 18

What does pepsinogen do?

Answer 18

It gets converted into pepsin, which digests protein

Question 19

Why is hydrochloric acid released?

Answer 19

It promotes pepsin activity and kills microorganisms

Question 20

Why is rennin important?

Answer 20

It breaks down casein in milk products.

Question 21

What are the three muscle layers in the stomach?

Answer 21

Outer - longitudinal
Middle - circular
Inner - oblique

Question 22

What are rugae?

Answer 22

Gastric folds in the inner layer of the stomach. Present in an empty stomach and disappear when distended

Question 23

What are the functions of the rugae?

Answer 23

Rugae both allow the stomach to stretch in order to accommodate large meals and help to grip and move food during digestion.

Question 24

What are mucosa?

Answer 24

Simple columnar epithelium with gastric pits

Question 25

Why do ruminants have foregut fermentation?

Answer 25

Specialised stomach for cellulose digestion by commensal bacteria