Cell recognition/Immunity 3.2.4 Flashcards
What are 3 features of the non-specific immune system?
- The response is immediate.
- The response is the same for all pathogens.
- The response involves physical barriers and phagocytosis.
What are 3 features of the specific immune system?
- The response is slower.
- The response is specific to each pathogen.
- The response involves lymphocytes.
What must lymphocytes be able to do?
- Distinguish between self and non-self material.
What are the proteins on the surface of cell membranes that are able to detect foreign material called?
- Antigens.
What is a phagocyte?
- A type of white blood cell which carries out phagocytosis.
What is phagocytosis?
- Mechanism by which cells engulf a pathogens to form a vesicle.
Outline phagocytosis in 6 steps…
1) Phagocyte is attracted to a foreign chemical left behind
2) Phagocyte attaches to chemicals on the surface pf the pathogen via receptors.
3) Cytoplasm of the phagocytes moves around the pathogen and engulfs it causing a phagosome to be produced.
4) A lysosome fuses with a phagosome, releasing lyzozymes enzymes into phagosomes.
5) Lyzozymes hydrolyse the pathogen.
6) Phagocyte presents pathogen’s antigens on its surface.
What are 3 features of T lymphocytes?
- Made in the bone marrow.
- Matured in the thymus gland.
- Involved in the cell mediated response.
What are 3 features of B lymphocytes?
- Made in the bone marrow.
- Matured in the bone marrow.
- Involved in the humoural response.
Outline the cell-mediated response in 4 steps…
1) Phagocytosis occurs
2) Phagocyte presents antigens on its surface.
3) T helper cells bind to the antigen via specific T-cell receptors.
4) The binding activates T helper cells to divide rapidly by mitosis.
What cells do T helper cells produce?
- Memory B cells
- Stimulate phagocytes to engulf pathogens by phagocytosis
- B cells
- Cytotoxic T cells.
What is the role of cytotoxic T cells?
- To kill abnormal cells and body cells infected by pathogens.
How do cytotoxic T cells kill abnormal cells?
- By producing perforin, a type of protein.
- Perforin makes holes in the membrane allowing full permeability causing cells to die.
What is an antibody?
- A protein produced by B lymphocytes in response to the presence of the antigen.
Outline the humoural response in 7 steps…
1) Surface antigens of an invading pathogen are taken in by endocytosis.
2) B cells process antigens and present them on cells.
3) T helper cells attach to receptors on the APC B cell to activate it.
4) B cells divides by mitosis (clonal selection) to produce plasma cells.
5) Plasma cells are produced which create antibodies specific to the antigen on the pathogen’s surface.
6) Antibody-antigen complex is formed causing agglutination, making it easier for phagocytes to engulf pathogens.
7) B cells form memory cells which can rapidly divide into plasma cells.
Why is the secondary response more efficient than the primary response?
- Secondary response allows antibodies to be produced at a faster rate.
- Memory B cells can divide rapidly into plasma cells that produce specific antibodies to the antigen.
What is a vaccine?
- The injection of an inactive pathogen which stimulates an immune response against a pathogen.
Why are vaccines important?
- Vaccines stimulate memory cell production against a disease for the future.
What is herd immunity?
- Herd immunity occurs when a large portion of a population becomes immune to a disease, either through vaccination or prior infection.
- thereby reducing its spread and protecting those who are not immune.
What is antigenic variability?
- Antigenic variability is the ability of pathogens to alter their surface proteins to evade detection by the host’s immune system.
What is active immunity?
- Active immunity is the protection against disease developed by an individual’s immune system after exposure to a pathogen or through vaccination.
What is passive immunity?
- Passive immunity is the temporary protection against disease gained by receiving antibodies from another source, such as maternal antibodies or antibody injections, without the immune system generating its own response.
