Human immune system

Question 1

Which line of defence/s belongs to the innate immunity system

Answer 1

1st line (barriers) and 2nd line (killing pathogens)

Question 2

What is adaptive immunity?

Answer 2

requires the 3rd line of defence, where the body fights of a SPECIFIC pathogen

Question 3

Identify the physical and chemical barriers of the 1st line of defence in a humans immune system

Answer 3

Physical barriers
mucus membrane - which secretes mucus to trap foreign substances

Cilia - hair like organelles that traps foreign substances and moves mucus

Skin - the surface contains dry cells that makes it difficult for pathogens to penetrate.

Question 4

What occurs in the 2nd line of defence in the humans immune system?

Answer 4

The 2nd line of defence is activated in response to kill the presence of pathogens in the body.
This includes:
- inflammation
- Phagocytosis

Question 5

Explain the process of inflammation and what it does to the body

Answer 5

The inflammatory response is triggered when cells are under stress.
- This is detected by mast cells in which it release chemicals

• Mast cells then release histamine and cytokines into the bloodstream

Question 6

Define cytokines

Answer 6

a chemical signal that attracts more white blood cells to the affected site

Question 7

Define histamines

Answer 7

cause vasodilation (dilation) so that more blood can reach to the affected site. This increases vessel permeability.

Question 8

What are the symptoms of inflammation?

Answer 8

Symptoms of inflammation
Swelling
Redness
Aching in the body
Feeling feverish
High temperature

Question 9

What is phagocytosis?

Answer 9

Phagocytosis is essentially a process where white blood cells destroy a pathogen. In the 2nd line, phagocytes engulf the infected cell with digestive lysosomes.

Question 10

Explain the process of phagocytosis

Answer 10

Process:
1. Pathogen undergoes endocytosis

2. Lysosome breaks down pathogen
3. Remaining material from the phagolysosomes is excreted by the cell

Question 11

What is the 3rd line of defence?

Answer 11

The 3rd line of defence is adaptive or in other words specific. This is divided into two responses which requires specialised lymphocytes called T and B cells.

Question 12

What is the role of the humoral response?

Answer 12

B lymphocytes produce plasma cells which starts the production of antibodies.

Question 13

Explain the role of memory B cells

Answer 13

Memory B cells help the immune system remember how to fight off a specific pathogen.
Within 4 days, via mitosis they produce plasma cells.

Question 14

Explain the role of plasma cells

Answer 14

Plasma cells produce antibodies that help fight off infection or disease.

Question 15

What is the cell mediated response?

Answer 15

the cell mediated response which is directed by T lymphocytes controls the immune system’s response. This is activated when a helper t cell receptor protein matches with the antigen presented in the B cell. The activated T cell essentially produces other forms to stimulate the immune response.

Question 16

Explain the role of cytotoxic T cells (killer)

Answer 16

A type of cell that does not directly attack the pathogen but recognises and kills infected body or cancer cells. They do this by releasing perforin which penetrates the cell membrane, causing the cell to burst.

Question 17

Explain the role of memory T cells

Answer 17

Their function is to recognise the antigen rapidly if it reappears in second exposure. From this, symptoms disappear much faster or aren’t present at all. Like B memory cells, they remain in circulation in the lymph nodes in preparation for secondary infection.

Question 18

Explain the role of suppressor T cells

Answer 18

Suppressor T cells inhibit the immune response once the pathogen is removed from the body to prevent hypersensitivity and overreactions