Alpha Flashcards
Name the two types of lymphocytes.
T lymphocytes and B lymphocytes
What response are T lymphocytes involved in?
Cell-mediated response
As a general statement, how are lymphocytes able to defend the body?
By being able to distinguish between molecules which are self and non-self.
What allows the immune system to identify non-self?
The specific proteins on the pathogens surface.
Give two examples of non-specific defence mechanisms.
Physical barrier and phagocytosis.
The lymphocyte which fits a specific protein is stimulated to do what?
Divide to build up its numbers to a high level.
What is the next line of defence after physical barrier?
Phagocytosis
What is the role of the receptors on the cell surface membrane of a phagocyte?
They attach to chemical on the surface of the pathogen.
What occurs after phagocytosis?
The primary immune response
Define antigen
Any part of an organism that is recognised by the immune system as being non-self.
Where are lymphocytes produced and what are they produced by?
In the bone marrow by stem cells
Where do B lymphocytes mature?
In the bone marrow
What process are B lymphocytes associated with?
The humoral response. (Antibodies)
Where do T lymphocytes mature?
In the thymus gland
What are cells called which display foreign antigens on their surface?
Antigen-presenting cells
What does a phagocyte do after engulfing and breaking down a pathogen?
It displays the antigens from the pathogen on its cell surface membrane.
What can T cells do (list 4 things)?
Develop into memory cells, stimulate phagocytosis, stimulate B cells, activate cytotoxic T cells
What do cytotoxic T cells do?
They kill cells infected by pathogens.
How do cytotoxic T cells kill infected cells?
They produce a protein called perforin which makes holes in the cell membrane.
State two differences between a specific and a non specific defence mechanism.
Non-specific mechanisms are quicker and the same response is given for all pathogens.
What are commonly used as antigens?
Proteins
How do T lymphocytes respond to a phagocyte displaying foreign antigens?
-receptors on a specific helper T cell fit onto these antigens -this attachment causes the T cell to rapidly divide by mitosis
How do B cells respond to invading pathogens?
-the antigens of a pathogen are taken up by a B cell -it processes them and displays them in its surface -helper T cells attach to these antigens, activating the B cell -the B cell divides via mitosis producing plasma cells -plasma cells secrete antibodies
