UNIT 3 - KA5

Question 1

Describe what is meant by pathogen

Answer 1

A pathogen is a bacterium, virus or other organism that can cause disease

Question 2

What are the three lines of defence against infection by a pathogen

Answer 2

1- physical and chemical barriers to infection
2- non specific cellular defences
3- specific cellular defences

Question 3

Explain the term non - specific in relation to immunity

Answer 3

This type of immunity is directed against any pathogen/cell- doesn’t matter what it is

Question 4

Describe how epithelial surfaces offer physical protection against pathogens.

Answer 4

• epithelial cells form a physical barrier
• closely-packed epithelial cells are found in the skin and inner lining of the digestive and respiratory systems

Question 5

Which type of secretions are produced against invading pathogens

Answer 5

Chemical secretions are produced against invading pathogens

Question 6

Which chemical secretions are produced against invading pathogens

Answer 6

Secretions include tears, saliva, mucus and stomach acid

Question 7

How does the body response to a physical injury or invasion by microorganisms

Answer 7

When the body suffers from physical injury such as cut and/or invasion by microorganisms, it responds with a defence mechanism called the inflammatory response

Question 8

Which cells initiate the inflammatory response

Answer 8

A group of immune cells called mast cells are responsible for initiating this response

Question 9

What chemical is released by mast cells during the inflammatory response

Answer 9

Histamine is released by mast cells during the inflammatory response

Question 10

What are the two effects of histamine on the body

Answer 10

• causing blood vessels (small arteries) in the injured area to vasodilate
• blood capillary walls become more permeable (leaky)

Question 11

What are the benefits of increased blood flow and capillary permeability during the inflammatory response

Answer 11

The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.

Question 12

The inflammatory response - summary

Answer 12

Histamine is released by mast cells causing vasodilation and increased capillary permeability. The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.

Question 13

What do phagocytes do to pathogens

Answer 13

Phagocytes recognise pathogens and destroy them by phagocytosis

Question 14

Brief description of the process of phagocytosis

Answer 14

Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes

Question 15

What do phagocytes release

Answer 15

Phagocytes release cytokines which attract more phagocytes to the site of infection

Question 16

What are cytokines

Answer 16

Cytokines are protein molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection