Immunity-Cellular response

Question 1

Describe process of phagocytosis to destroy a pathogen (5)

Answer 1

-Phagocyte attracted towards pathogen by chemical products pathogen ( foreign antigens ). Moves towards path, along conc gradient.
-Phagocyte has several receptors on its cell surface membrane that attach to chemicals on surface of pathogen
-Lysosomes within the phagocyte migrate towards phagososme (formed by engulfing pathogen)
-Lysosomes release lysozymes into the phagosome, where they hydrolyse the pathogen
-Phagocyte presents the pathogen’s antigens - it sticks the antigens on its surface to activate other immune system cells

Question 2

Describe the role of Th-cells.

Answer 2

-Receptor proteins on surface of Th cell binds to complementary antigens presented by phagocytes
-This stimulates Th cells to release chemical signals which:
1 ) stimulate phagocytosis
2 ) activate Tc cells, which kill abnormal and foreign cells
3 ) activate B-cells

Question 3

Describe the role of B-cells.

Answer 3

1 ) when the protein on the surface of the B-cell meets complimentary shaped antigen, it binds to it.
2 ) This binding + substances released from helper T-cells activates the B-cell to divide into plasma cells
3 ) This process is called clonal selection

Question 4

What is the difference between the cellular and humoral response ?

Answer 4

-Cellular - (antigens on cells )Response of T-lymphocytes to foreign antibodies
-Humoral - ( antigens in body fluid )Response of B-Lymphocytes to a foreign antigen,

Question 4

What is the difference between the cellular and humoral response ?

Answer 4

-Cellular - response to antigens on the surface of cells
-Humoral - response to antigens free in body fluids

Question 5

Describe the primary immune response ( with reference to Plasma cells and memory cells )

Answer 5

-slow response to first infection due to lack of B-cells to make antibody needed to bind to it ( primary response )
-Eventually, enough antibodies produced to get rid of disease, meanwhile person shows symptoms of disease
-After being exposed to an antigen, B-cells and T-cells produce memory cells which stay in the body for a long time
-Memory T remember specific antigen, memory T remember specific antibody needed
-Person now immune, have ability to respond quickly to infection

Question 6

Describe the secondary immune response ( with reference to Plasma cells and memory cells )

Answer 6

-Upon reinfection by same pathogen-antigen immune system produces stronger and quicker immune response ( secondary response )
>Memory B cells are activated and divide into plasma cells (Clonal selection), so more antibodies produced
>Memory T cells are activated and divide into Cytoxic T cells to kill pathogen
-Secondary response often gets rid of pathogen before results of infection even show