T Lymphocytes Flashcards
What is an antigen?
- Antigen is any part of an organism or substance that is recognised as foreign by the immune system and stimulates an immune response.
- Antigens are usually proteins that are a part of the cell surface membranes or cell walls of invading cells.
- The presence of an antigen triggers the production of an antibody as a part of the body’s defence system.
What type of immune response is phagocytosis?
Non specific
Where are lymphocytes produced?
Stem cells in the bone bmarrow
What are the two type of lymphocyte?
- T lymphocytes
* B lymphocytes
Why are B cells called what they are?
- Mature in the bone marrow.
* They are associated with humoural immunity, .
Why T cells called what they are?
- Mature in the thymus gland.
* Associated with cell mediated immunity.
What is humoural immunity?
immunity involving antibodies that are present in body fluids, or humour such as blood plasma
What is cell mediated immunity?
immunity involving antibodies that are present in body fluids, or humour such as blood plasma I
How can T lymphocytes distinguish invader cells from normal cells?
- Phagocytes that have engulfed and hydrolysed a pathogen present some of a pathogens antigens on their own cell surface membrane.
- Body cells invaded by a virus present some of the viral antigens on their own cell surface membrane.
- Cells from individuals of the same species have different antigens on their cell surface membrane
- Cancer cells are different from normal body cells, and antigens on their cell surface membrane.
What do lymphocytes respond to?
- Cells that have been infected by a foreign material from a different species.
- Cells from another individuals of the same species, as they are genetically different, thus have different antigens on their surface membrane from the antigen on the organism’s own cells.
What are antigen presenting cells?
- Cells that display foreign antigens on their surface.
* They can present antigens of other cell cells on their own cell surface membrane.
What do T lymphocytes respond to?
- Antigens that are presented on a body cells ( as opposed to antigens within the body fluids )
- This type of response is called cell mediated immunity/cellular response.
What is the role of receptors on T cells?
Receptors on each T cell respond to a single antigen, meaning there is a vast number of different types of T cell.
What do the receptor proteins on the surface of T cells do?
Bind to complementary antigens presented to it by phagocytes, activating the T cell.
How do T lymphocytes respond to infection?
- Pathogens invade body cells, or are taken in by phagocytes.
- Phagocyte places antigens from the pathogen on its cell surface membrane.
- Receptors on a specific helper T cell, fit exactly onto these antigens
- Attachment activates the T cell to divide rapidly via mitosis and form a clone of genetically identical cells.
