Defence Mechanisms Flashcards
What is an infection?
This is an interaction between a pathogen and the body’s various defence mechanisms.
What is immunity?
This is the ability of organisms to resist infection by defending against disease-causing micro organisms or the toxins that invade their bodies.
Who are most vulnerable to death by infection?
Ill people
Elderly people
Young children
What are the two types of responses by lymphocytes?
Cell-mediated
Humoral
What are lymphocytes?
A type of white blood cell
What type of lymphocyte do cell-mediated responses require?
T lymphocytes
What type of lymphocyte do humoral responses involve?
B lymphocytes.
What would happen if lymphocytes could not distinguish between self and non-self cells?
They would destroy the body’s own tissues.
What do all cells have?
They have specific molecules in its surface that identify it regardless of it being self or non-self.
Why are the protein molecules on the surface of cells the most important?
They have a specific 3D tertiary structure that allows lymphocytes to distinguish them from each other.
What four things do proteins enable lymphocytes to identify?
Pathogens
Non-self material such as cells from different members of the same species.
Toxins
Abnormal body cells such as cancer cells
What is a problem with organ and tissue transplants?
The lymphocytes attempt to destroy them.
How is tissue or organ donor rejection reduced?
The tissue or organ is closely matched.
Immunosuppressant drugs are used.
Are specific lymphocytes produced as a result of an infection?
No, they already exist but more are made.
Explain how lymphocytes recognise the cells that belong to the body whilst the placenta.
In the foetus, the lymphocytes constantly collide with other cells. The lymphocytes collide exclusively with the body’s own material.
If the lymphocyte has receptors that fit the body’s own cells it is suppressed or dies.
