14.3 Flashcards
(18 cards)
What are the 2 main types of lymphocytes? (2)
Where are they produced? (2)
Where do they mature? (2)
(1) T lymphocytes —> (1) bone marrow —> (1) thymus gland
(2) B lymphocytes —> (2) bone marrow —> (2) bone marrow
What type of immunity are T lymphocytes associated with? (1)
cell-mediated immunity (immunity involving body cells)
What type of immunity are B lymphocytes associated with? (1)
humoral immunity (immunity involving antibodies present in body fluids)
What is an antigen? (2)
(1) any part of an organism or substance that is recognised as non-self (foreign) by the immune system
(2) and stimulates an immune response
What are antigens usually made of? (1)
Proteins that are part of the cell-surface membranes or cell walls of invading cells or abnormal body cells
What is the initial response of the body to infection? (1)
Non-specific responses
Why do lymphocytes respond to an organism’s own cells that have been infected by a virus? (1)
Because the** infected cells present** some of the viral antigens on their own cell-surface membrane
Why do lymphocytes respond to cells from other individuals of the same species? (2)
(1) Because these cells are genetically different
(2) and have different antigens on their cell-surface membranes
What type of APCs (antigen presenting cells) do T lymphocytes distinguish? (4)
(1) phagocytes (they present the antigens that are from the pathogen they engulfed)
(2) body cells invaded by a virus (present some of the viral antigens)
(3) transplanted cells
(4) cancer cells
What are APCs? (1)
they are cells that display foreign antigens on their cell-surface membrane
Why is the type of immunity called “cell-mediated”? (1)
because T lymphocytes will only respond to antigens that are presented on a body cell (rather than to antigens within the body fluids)
The receptors on each T cell respond to a __(1)__ ___(2)___, which is why there is a vast number of different __(3)__ of T cell, each one responding to a ____(4)____ ___(2)___.
(1) single
(2) antigen
(3) types
(4) different
Describe the stages in the response of T lymphocytes to infection by a phagocyte. (5)
(1) Pathogens (invade body cells or) are taken in by phagocytes
(2) The phagocyte presents antigens from the pathogen on its cell-surface membrane
(3) Receptors on a specific T helper cell (TH cell) fit exactly onto these antigens
(4) this attachment activates the TH cell to divide rapidly by mitosis & form clones of genetically identical cells
(5) the cloned TH cells:
- develop into memory cells
- stimulate phagocytes
- stimulate B cells to divide & secrete their antibodies
- activate cytotoxic T cells (TC cells)
NOTE: to visualise the process of cell-mediated immunity / cellular response, check figure 1 on page 181
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How do cytotoxic T cells (TC cells) kill infected cells? (4)
(1) they produce a protein called perforin,
(2) which makes holes in the cell-surface membrane,
(3) which then causes the cell membrane to be freely permeable to all substances, so the cell dies as a result
Why are T cells most effective against viruses? (2)
(1) Because viruses replicate inside cells
(2) so the sacrifice of body cells prevents viruses multiplying & infecting more cells
What is the relationship between antibiotics and immunity? (1)
Antibiotics have nothing to do with immunity
ADDITIONAL TASK: Blurt by drawing the process of Cell-Mediated Immunity and label your diagram. (5)
Check your answer using Figure 1 from Page 181
