11) Immunity Flashcards
(28 cards)
what is a pathogen and how do they cause harm ?
- microorganism that causes disease.
- they produce toxins and cause damage to host cells & tissues.
what is immunity?
protection against disease provided by the body’s immune system
what is a non self antigen ?
- FOREIGN substance
- stimulates IMMUNE RESPONSE
- PROTEIN
what is an immune response ?
series of responses of body to the entry of a foreign antigen. Involves lymphocytes & phagocytes
what are 3 physical barriers to infection ?
- skin is a tough physical barrier consisting of keratin
● stomach acid (hydrochloric acid) which kills bacteria
● gut and skin flora – natural bacterial flora competes with pathogens for food and space
what are the 2 types of phagocytes ?
- neutrophil
- macrophage
where do phagocytes develop and store?
bone marrow
what do phagocytes do ?
remove dead cells & invade microorganisms by phagocytosis
state 4 facts about neutrophils.
- can squeeze through capillary walls into the tissues.
- released in large numbers from bone marrow during infection.
- short lived cells (die after phagocytosis).
- dead neutrophils often collect at site of infection and form pus.
state 4 facts about macrophages
- develop from monocytes (which travel round body in blood)
- kill microorganisms before they enter the blood.
- long lived cells.
- develop into macrophages when they leave the blood and settle in organs (eg lungs, liver)
give 6 steps of phagocytosis
- chemoattractants cause phagocytes to move towards pathogen = chemotaxis. pathogen binds to receptors on phagocyte membrane.
- receptors on phagocytes’ cell surface membrane recognise & attach tp chemicals on surface of pathogen.
- phagocytes engulf the pathogen to form a phagosome = ENDOCYTOSIS. Lysosome move towards the phagosome and fuse w it.
- Lysozymes & protease in the lysosome destroy ingested bacteria by hydrolysis of their cell walls. The process hydrolyses large insoluble molecules into smaller, soluble ones.
- soluble products from breakdown of pathogen are absorbed into cytoplasm of phagocyte.
- indigestible parts of bacteria are discharged from phagocyte by EXOCYTOSIS.
state 2 types of lymphocytes
- B lymphocytes
- T lymphocytes
give 4 differences between B and T lymphocytes
- B matures in bone marrow, T matures in Thymus gland.
- B is associated with humoral immunity involving antibodies, T is associated w cell mediated immunity (body cells).
- B make antibodies, T have cell surface receptors.
- Once mature, B can only make 1 antibody specific to antigen, T has diff receptor specific to antigen.
What happens to T cells after activated ?
- divide by mitosis
- release cytokines (stimulate macrophages to increase rate of phagocytosis)
- release cytokines to activated B lymphocytes to divide and develop antibody secreting plasma cells.
- stimulate T killer cells.
2 types of b lymphocytes ?
- plasma cells (secrete antibodies)
- memory B cells (involved in secondary immune response)
Outline the roles of T-lymphocytes in primary immune response
- activated by antigens
- specific to the antigen
- secrete cytokines
Outline the roles of B-lymphocytes in primary immune response
- production of memory cells
- antibody production
- plasma cells formed
describe what plasma cells do (B lymphocyte)
- secrete antibodies directly
- antibodies destroy pathogens/toxins.
- responsible for primary immune response.
- only survive for few days
describe what memory cells do (B lymphocyte)
- do not produce antibodies directly but circulate in blood & tissue fluid.
- if encounter same antigen later, develop into plasma cells.
- provide long term immunity = secondary immune response.
- live longer than plasma (sometimes decades)
How do B lymphocytes recognise non-self antigens
- antibodies on surface act as receptors
- these antibody receptors bind to the non-self antigen
outline the stage where hybridoma cells are formed
- cell membrane fuses
- spleen cells (plasma cells) fuse with cancer (myeloma) cells.
- hybridogen used in the process
outline the use of monoclonal antibodies in treatment of disease
- bind to specific antigens
- attach to enzymes
- drug for treatment can be activated
outline the procedure for producing mAbs suitable for use in another mammal
- inject hamster w antigen
- pick out the plasma cells which can make the antibody
- fuse these plasma cells with cancer cells (myeloma cells)
- hybridogen can be used
use of monoclonal antibodies in disease diagnosis
- locate position of blood clots
- locate cancer cells
- identify exact strain of virus
