3.5 - 3.8 Flashcards
What causes allergies?
B lymphocytes can respond to antigens on substances that are harmless to the body
Explain the characteristics of T
lymphocytes - (3 points)
• Destroy cells by apoptosis
• Found in the thymus gland
• Once a specific antigen binds to the lymphocytes receptor, a clonal population of the lymphocyte is produced
What does the
Immune System do?
defends itself against pathogens, some toxins & cancer cells
What are pathogens?
• Pathogens are disease causing organisms
What are antibodies?
• antibodies are y shaped protein molecules that have receptor binding sites specific to a particular antigen on a pathogen
Explain the characteristics of B lymphocytes.
• Produced in the bone marrow
• Produces antibodies that have receptor binding sites to a particular antigen
• Antibodies inactivate the pathogen which is then destroyed by phagocytosis
Explain the steps of phagocytosis
- Phagocytes recognise pathogens and engulf them
- Phagocytes forms a vacuole around the pathogen and lysosomes containing lysosyme move towards & fuse with the vacuole
- The lysosyme digests the pathogen
Explain the steps of the inflammatory response
• Pathogen enters the body and damages the mast cells and activates them and that causes a release of histamine.
• Histamine diffuses to blood capillaries & causes vasodilation & increases capillary permeability which increases fluid & blood flow causing redness & swelling
• Phagocytes engulf pathogens & secrete cytokines & clotting elements that prevent other pathogens entering
the world
What is immunity?
the ability of the body to resist infection by a pathogen and destroy an organism if it invades and infects the body
What is the Second Line of Defence?
non-specific responses by immune cells
eg. the inflammatory response & phagocytosis
What are cytokines?
protein molecules that act as a signal to specific WBC’S to attract them to the site of infection
they also initiate the specific immune response
What is the First Line of Defence?
Physical & chemical
defences
eg. epithelial cells & mucus
Explain the process of apoptosis
T lymphocytes inject their proteins into the infected cells causing the production of self destructive enzymes which cause programmed cell death
the remains are then removed my phagocytosis
What is Clonal Selection Theory?
When a lymphocytes membrane receptor binds to its specific antigen, it becomes activated & divides repeatedly to form a clonal population of identical lymphocytes
What is the Third Line of Defence?
a pathogen specitic response by
immune cells to destroy or remove pathogens
eg. T & B lymphocytes & immunological response
What are phagocytes?
non- specific WBCs which engulf pathogens & destroy them
What are antigens?
molecules located on the surface of cells that trigger a specific immune response
