T lymphocytes and cell-mediated immunity Flashcards
What is immunity?
The ability of organisms to resist infection by protecting against disease-causing microorganisms or their toxins that invade their bodies. It involves the recognition of antigens
What is an antigen?
An antigen is any part of an organism or substance that is recognised as non-self by the immune system and stimulates an immune response.
What are antigens usually?
Proteins that are part of the cell surface membrane or cell walls of invading cells.
What does the presence of an antibody trigger?
The production of an antibody as part of the body’s defence system.
What are specific immune responses?
Responses to specific antigens, they take longer but can provide long-term immunity.
Where do B lymphocytes mature? What type of immunity are they associated with?
Bone marrow.
Humoral.
Where do T lymphocytes mature and what type of immunity are they associated with?
Thymus gland
Cell-mediated immunity.
What four cells are distinguished as non self?
Phagocytes that have engulfed hydrolysed a pathogen
Body cells infected by pathogen
Cancer cells
Transplanted tissue cells
Summarise the stages of T lymphocytes response.
Receptors on t helper cell fit attach to antigens presented by phagocytes
This activated the T cell to divide by mitosis
The cloned T cells develop into memory cells, stimulate phagocytes and B cells and they activate cytotoxic T cells.
How do cytotoxic T cells kill cells?
By producing a protein called perforin that makes holes in the cell membrane, causing it to be freely permeable to all substances.
What are T cells most effective against?
Virus infected cells as it prevents the virus from spreading. (They replicate inside host cells of our body)
