Chapter 5 - Immunology Flashcards
What type of lymphocyte is involved in a cell mediated response?
T lymphocytes
What type of lymphocyte is involved in a humoural response?
B lymphocyte
How does the immune system distinguish self from non self?
Proteins on the surface allow the immune system to identify, pathogens, non self but same species, abnormal body cells, toxins
name 2 non specific defence mechanisms
skin and phagocytosis
What are antigens?
proteins on the surface of cells which stimulate an immune response
What is a pathogen?
an organism which causes a disease by destroying host cells or producing toxins
Name 2 immune responses which are cell mediated
Phagocytosis and t cells
Name 2 immune responses which are humoral
B lymphocytes and Plasma cells
Describe phagocytosis (5 key steps)
1) the phagocyte recognises the foreign antigens on the pathogen
2) the phagocyte engulfs the pathogen
3) the pathogen is now contained in a phagocytic vacuole
4) a lysosome fuses with the vacuole and releases lysozymes to hydrolyse the pathogen
5) the phagocyte becomes antigen presenting and activates other immune cells
describe the role of helper t cells
helper t cells bind to specific antigen on the antigen presenting cell (phagocyte) activating the release of chemical signals that activate cytotoxic t cells, phagocytes and B cells
describe the role of B cells (3 points)
1) when antibody meets complementary antigen they bind
2) this along with helper T cell substances, activates the B cell. (step 1 + 2 are called clonal selection)
3) the activated B cells divide into plasma cells
what is the role of a plasma cell?
to make more antibodies specific to an antigen
what is agglutination?
the process by which pathogens become clumped together - can be destroyed all at once
compare the primary and secondary immune response
PRIMARY - slow, symptoms felt, memory B cells saved
SECONDARY - faster/stronger so no symptoms felt,
What is HIV?
Human Immunodeficiency Virus
How does HIV affect the body?
infects helper t cells and weakens the immune system
causes AIDS
What is AIDS
Acquired Immune Deficiency Syndrome
What enzyme is present in viruses?
Reverse transcriptase
How does HIV (and other viruses) use the host mechanisms to replicate?
the attachment proteins bind to specific receptors on the host cell
reverse transcriptase makes DNA from RNA
Virus DNA enters nucleus through nuclear pore
Host cell makes more copies of RNA and reverse transcriptase
capsid reforms
leaves host cell by exocytosis
