4.1.1 Communicable Disease and Prevention – Non-specific Defence in Animals

Question 1

What type of immune response targets a wide range of pathogens?

Answer 1

The non-specific immune response.

Question 2

Name the external barrier that protects the body from pathogen infection.

Answer 2

The skin.

Question 3

Name the main protein found in the skin that provides protection.

Answer 3

Keratin.

Question 4

What is skin flora and what is its function?

Answer 4

• The skin flora consists of bacteria that live on the surface of the skin.
• It competes with pathogens for space and nutrients, preventing pathogens from colonizing the skin.

Question 5

Name the internal barriers that line internal organs to prevent pathogen infection.

Answer 5

Mucous membranes.

Question 6

How do goblet cells and ciliated epithelium cells work together to remove pathogens from the breathing system?

Answer 6

• Goblet cells secret a sticky mucus.
• The mucus traps pathogens that are breathed in.
• The cilia waft the mucus to the top of the throat.
• The mucus and trapped pathogens get swallowed and move to the stomach to be destroyed.

Question 7

Name the chemical in the stomach that destroys pathogens that are swallowed.

Answer 7

Hydrochloric acid.

Question 8

Name the enzyme found in saliva, tears and sweat that destroy pathogens.

Answer 8

Lysozyme.

Question 9

What are interferons and what are their function?

Answer 9

• They are proteins produced by virus- infected body cells.
• They trigger the production of a second protein that inhibits viral replication.

Question 10

State 2 expulsive reflexes that remove foreign particles/pathogens from the body (state the parts of the body they are removed from).

Answer 10

• Coughing (removes foreign particles/pathogens from the respiratory tract)
• Vomiting (removes foreign particles/pathogens from the stomach)

Question 11

Name the chemical that is produced to initiate inflammation and name the cells that produce it.

Answer 11

Histamine, produced by mast cells.

Question 12

What causes the redness and swelling at an inflamed area?

Answer 12

Redness – histamine causes vasodilation so there is an increased blood flow to the area of infection.
Swelling - histamine causes the capillary walls to become more permeable so that tissue fluid is squeezed out of the vessels.

Question 13

Name the cells that move out of the capillaries to destroy any pathogen at the site of infection.

Answer 13

Phagocytes.

Question 14

What happens to blood at the site of a wound to prevent pathogen infection and seal the wound?

Answer 14

Coagulation/formation of a blood clot.

Question 15

What are the 3 main components of a clot?

Answer 15

Red blood cells, platelets and fibrin.

Question 16

When a blood vessel is damaged and collagen fibres are exposed, what clotting factors are released?

Answer 16

Thromboplastins.

Question 17

What reaction is activated by the clotting factors?

Answer 17

Prothrombin (an inactive plasma protein)  thrombin (an active plasma protein).

Question 18

What reaction does thrombin activate?

Answer 18

Fibrinogen (soluble)  fibrin (insoluble)

Question 19

What happens to the clot once it dries out?

Answer 19

It forms a scab.