The Digestive System

Question 1

What are the main functions of the digestive system?

Answer 1

Ingestion.
Propulsion.
Digestion.
Absorption.

Question 2

What is the function of ingestion?

Answer 2

The taking of food into the alimentary tract e.g eating and drinking.

Question 3

What is the function of propulsion?

Answer 3

This mixes the ingested contents and moves them along the alimentary tract.

Question 4

What is the function of digestion?

Answer 4

Mechanical breakdown of food e.g chewing.

Chemical breakdown of food into small molecules by enzymes.

Question 5

What is the function of absorption?

Answer 5

This is the process where products of digestion pass through the walls of some organs of the alimentary canal into the blood for circulation around the body.

Question 6

What are the functions of the liver?

Answer 6

Carbohydrate metabolism. 
Fat metabolism. 
Protein metabolism. 
Breakdown of erythrocytes and defence against microbes. 
Detoxification of drugs and toxic substances. 
Inactivation of hormones. 
Production of heat. 
Secretion of bile. 
Storage.

Question 7

Explain the livers function in carbohydrate metabolism

Answer 7

The liver has an important role in maintaining plasma glucose levels.
When glucose levels rise, glucose is converted into glycogen for storage. When glucose levels later fall, glucagon stimulates conversion of glycogen back into glucose to maintain body levels.

Question 8

Explain the livers function in Fat Metabolism.

Answer 8

Stored fat can be converted into a form which it can be used by the tissues to provide energy.

Question 9

Explain the livers function in Protein Metabolism

Answer 9

This process:

• Removes the nitrogenous portion from excess amino acids - forming urea which is excreted in urine.
• Breaks down nuclei acids to form uric acid, which is excreted in urine.

Question 10

Explain the livers function: Detoxification of drugs and toxic substances.

Answer 10

This includes ethanol, waste products and microbial toxins. The liver inactivates the majority of drugs and toxins, so the blood leaving the liver is clean. This is why some drugs aren’t very effective when taken orally.

Question 11

Describe the function of the liver: Bile Secretion

Answer 11

Bile is formed in the liver by hepatocytes and stored in the gall bladder.

Question 12

What is the structure of the gall bladder?

Answer 12

• Peritoneum layer on the inferior surface as the superior surface is in direct contact of the liver.
• Muscle layer - the gall bladder has an additional layer of oblique muscle fibres.
• Mucous membrane which displayed a small rugae when the gall bladder is empty.

Question 13

What are the functions of the gall bladder.

Answer 13

Storage of bile.
Concentration of bile.
Release of stored bile.

Question 14

Name the organs of the digestive system.

Answer 14

• Mouth
• Salivary glands
• Alimentary canal
• Pharynx
• Stomach
• Small Intestine
• Large Intestine
• Pancreas
• Liver
• Gall Bladder

Question 15

What are the constituents of bile?

Answer 15

Water
Mineral salts
Mucus
Bile pigments (bilirubin)
Bile salts
Cholesterol.

Question 16

What are the functions of bile?

Answer 16

• Fat digestion

- Excretion of bilirubin