2 - Immunity

Question 1

Phagocytes

Answer 1

Stored and produced in bone marrow
Remove dead cells and microorganisms through phagocytosis
Non-specific, first line of defense

Two types:
-Neutrophils
-Macrophages

Question 2

Phagocytosis

Answer 2

Phagocyte attracted by chemical substance released by pathogen

Pathogen engulfed

Pathogen enclosed in vesicles

Lysosome containing digestive enzymes digest the pathogen

Phagosome is formed

Question 3

T - Lymphocytes

Answer 3

Produced in bone marrow, mature in thymus

Have T cell receptors that are specific to one antigen

Activated when they bind to an antigen presenting cell (clonal selection)

Once activated, they divide by mitosis (clonal expansion)

Differentiate into two types of T Cells:
1) Helper T Cells
-Release cytokines that stimulate
other immune cells
2) T Killer Cells
-Recognise and kill infected/
abnormal cells by inducing aptosis

Question 4

B Lymphocytes

Answer 4

Remain in bone marrow until they mature

When mature, they spread through body, concentrated in lymph nodes and spleen

When mature, each type of B cell makes one type of antibody

When it recognises and binds to antigen, they divide and differentiate into two main types of cells
1) Plasma Cells
Produce antibodies with a
complementary shape to antigen
2) Memory Cells
Remain in bloodstream in case
reinfection occurs in which case they
rapidly divide into plasma cells

Question 5

Antigen

Answer 5

Glycoprotein receptor on cell surface used to signal an immune response

Question 6

Vaccine

Answer 6

deliberate introduction of an weakened
pathogen to cause an immune response