defence mechanisms Flashcards
(24 cards)
What are the types of defence mechanisms?
Specific and non-specific
Which response is quicker?
Non-specific
Which response is specific to each pathogen?
Specific
What are the types of non-specific responses?
Physical barriers, phagocytosis
What are the types of specific responses?
Cell-mediated responses, humoral responses
What is phagocytosis?
The engulfment and destruction of microorganisms by phagocytic cells
What can phagocytes also act as?
Antigen presenting cells
What does this involve?
Phagocyte removing antigen from the pathogen and presenting the antigen on their cell surface membrane to T cells
What does detection involve in phagocytosis?
The phagocyte detects the microbes by the chemicals they give off (chemotaxis)
What is the next step in phagocytosis?
Ingestion where the microbe is engulfed by the phagocyte membrane
What forms after this?
A phagosome
What does the phagosome fuse with?
Lysosomes which contain hydrolytic enzymes
What happens after this?
Microbe is hydrolysed
What is the final step of phagocytosis?
Indigestible matter is discharged
Where do phagocytes destroy pathogens?
The blood and tissues
Why do they do this?
To reduce them spreading to other parts of the body
What do these mechanisms involve?
The immune system
What do these responses provide?
Long lasting immunity
What does the humoral response involve?
B lymphocytes
What does cellular response involve?
T lymphocytes
When can specific responses begin?
When they have been activated
What are antigens?
Proteins or glycoproteins that appear foreign to the individual organism exposed to them
What do antigens activate?
The production of antibodies by B lymphocytes
Where may antigens be present?
On the surface of a pathogen, on the cell-surface membrane of other organisms of the same species, abnormal body cells, as a toxin
