immune responses

what white blood cell is involved in specific immune response?

lymphocytes

types of lymphocytes (2)

where are they produced?

where are they matured?

-T lymphocytes [T cells] →mature in thymus gland

-B lymphocytes [B cells] →mature in bone marrow

-both produced in bone marrow

structure of T lymphocyte

its surface is covered with receptors

note: Different T cells have different receptors on their surface so bind to a different antigen

-how are T lymphocytes activated?

what happens after T lymphocytes are activated?

-processes in the specific immune response involving T lymphocytes

-receptor on T lymphocyte bind to a complementary antigen on antigen-presenting cells [clonal selection]

-this activates the T lymphocyte and causes it to divide by mitosis to produce clones [clonal expansion]

•Clonal selection: when the receptor on a T cell binds to a complementary antigen, activating the T cell.

•Clonal expansion: divides by mitosis to produce clones

different types of T lymphocytes and their roles (3→main 2 explain)

T helper cells

-release interleukins (type of cytokine) to activate B lymphocytes

T killer cells

-destroy infected cells

T memory cells

structure of B lymphocytes

its surface is covered with antibodies

how are B lymphocytes activated? (2)

what happens after B lymphocytes are activated?

-processes in the specific immune response involving B lymphocytes

-antibody on a B lymphocyte bind to a complementary antigen. T helper cells release interleukins to activate the B lymphocyte. [clonal selection]

-The activated B lymphocyte divide by mitosis and differentiate into plasma cells and memory cells. [clonal expansion]

•Clonal selection: when the antibody on a B cell binds to a complementary antigen and the B cell is activated by a T helper cell

•Clonal expansion:divides by mitosis to produce clones

role of plasma cells

produce antibodies [that are complementary to antigen]

what is cell signalling

why is it important?

example

it’s how cells communicate with each other by releasing chemicals that bind to the receptors on other cells to trigger a response

it helps activate the specific white blood cells that are needed

e.g. T helper cells release interleukins that activate B lymphocytes

types of immune responses [immune system produces a response]

primary immune response

-happens when the body is exposed to a pathogen for the first time.

secondary immune response

-Happens when the body is exposed to the same pathogen again.

why is primary immune response slower than a secondary immune response?

bcs it takes time for B lymphocytes to undergo clonal selection and clonal expansion to produce specific antibodies

whats produced in the primary response?

both T and B cells produce memory cells

role of memory cells

they remain in the body and allow the immune system to respond more quickly if the same pathogen enters again.

what happens during secondary response?

the T and B memory cells will recognise the antigen and start dividing.

→T memory cells are activated and divide into T killer cells to help destroy infected cells.

→B memory cells will quickly divide into plasma cells which produce the correct antibodies that are complementary to the antigen

the person is immune to the pathogen

why is the secondary immune response quicker than primary?

-more antibodies are produced [bcs B memory cells quickly recognize the pathogen and divide into plasma cells]

-memory cells quickly recognize and rapidly divide into plasma cells or T killer cells. This happens faster because memory cells are already present and don’t undergo clonal selection.

compare the immune responses

→exposure to pathogen: when?

→speed

→cells activated

→symptoms (yes or no)

→rate of antibody production (low or high)

-similarities (2)

[note:contrast question→ only mention difference]

primary immune response

-exposed to pathogen for the first time

-slow

-B and T lymphocytes

-yes

-low

secondary immune response

-exposed to pathogen for the second time

-fast

-memory B and T cells

-unlikely

-high

SIMILARITIES

-both involve the production of antibodies

-both are triggered by the presence of a pathogen

Why does immunity not always last forever? how can it be maintained?

memory cells have a limited lifespan

can be maintained by being continuously exposed to the pathogen, which produces more memory cells