Chapter 5- Cell recognition and the immune system

Question 1

What is a defence mechanism

Answer 1

A defence mechanism is a way for the body to protect itself from pathogens

Question 2

Define an infection.

Answer 2

Am infection is an interaction between the pathogen and the body’s various defence mechanisms.

Question 3

Define a pathogen.

Answer 3

Any microorganism which causes disease.

Question 4

What is a specific defence mechanism ?

Answer 4

A specific defence mechanism is slower and specific to each pathogen.

Question 5

State two differences between a specific and a non-specific defence mechanism.

Answer 5

Specific- is able to distinguish between different pathogens but has a slower response.
Non-specific- treats all pathogens the same way but has a more rapid response.

Question 6

Describe the process of phagocytosis

Answer 6

Chemical products from the pathogen attract to the phagocyte
The phagocyte then engulfs the pathogen forming a phagosome.
Lysosomes inside of the phagocyte release lysozyme into the phagosome, hydrolysing the bacterium.
The hydrolysed products of the bacterium are absorbed by the phagocyte

Question 7

How do B cells ensure immunity once a pathogen is encountered for the first time ?

Answer 7

Antigens on the pathogen bind to the antibody on the B-cell Thai forms an antigen-antibody complex. The processed antigen and antibody is then stimulated by a complementary helper T-cell. Allowing the B-cell to divide by mitosis forming plasma cells. The plasma cells secrete antibodies which are complementary. Some of the B-cells are then able to develop into memory cells which stay in the bloodstream in order to be stimulated for a faster rapid secondary response.