6.3 The body's response to infection Flashcards
What is an antigen?
A molecule of a substance that the body regards as foreign or harmful.
What is an antibody?
A molecule produced by a B lymphocyte cell when it encounters a particular antigen.
What is lysozyme?
Enzyme found in tears, saliva and nasal secretions, that kills bacteria by breaking down their cell walls.
What is a CD4 receptor?
A receptor molecule found in the cell surface membrane of a particular type of lymphocyte called a T cell.
What is a neutrophil?
A type of white blood cell that forms part of the immune system of the body.
Able to leave blood capillaries by squeezing between the cells of the capillary walls. They remove bacteria from the body by engulfing and destroying them in phagocytosis.
What is a macrophage?
Type of large white blood cell.
They remove bacteria from the body by engulfing and destroying them in phagocytosis.
What is a phagocyte?
Phagocytes are white blood cells that engulf and destroy bacteria and cell debris in phagocytosis. They include both neutrophils and macrophages.
What is histamine?
A chemical released by white blood cells and damaged mast cells. Responsible for the increase in capillary permeability resulting in oedema, and dilation of capillaries resulting in reddening of the area from increased blood flow.
What are mast cells?
Cells found in connective tissue below the skin and around blood vessels, which release histamine in response to cell damage.
How does lysozyme break down bacterial cell walls?
By hydrolysing peptidoglycan in cell walls.
What are functions of the lymphatic system?
Carry excess tissue fluid back to the blood
Important in immune response
Transport substances
What does the lymphatic system consist of?
Lymph
Lymph vessels
Lymph organs (nodes, spleen)
What is lymph?
Like tissue fluid but has a higher concentration of fatty substances. Also contains proteins and white blood cells.
What happens when lymph passes through lymph nodes?
It is filtered of foreign substances, which are trapped in a network of fibres, and are then destroyed by activated lymphocytes and macrophages.
