Immunology and Disease

An organism that causes damage to its host

A disease that may be transmitted from one individual to another.

Shows no symptoms when infected but can pass the disease on to another.

Where a pathogen is normally found; this may be in humans or another animal and may be a source of infection.

A disease, which is always present at low levels in an area

Where there is a significant increase in the usual number of cases of a disease, often associated with a rapid spread.

Uses non-pathogenic forms, products or antigens of micro-organisms to stimulate an immune response, which confers protection against subsequent infection.

A protein on a foreign cell that is recognised by the immune system

A protein produced by the immune system to recognise and destroy antigens.

A chemical produced by a microorganism, which causes damage to its host.

A living organism which transfers a disease from one individual to another.

• Produce toxic substances • Viral cell transformation triggering cells to become cancerous • Infecting the white blood cells to suppress the immune system • Viral DNA instructing the cell to make viral particles leading to full cell lysis where the virus can then infect other cells and organisms

A tough barrier. Strong connective tissue maintained by vitamin C that prevents microbes entering the body. Skin flora competes with pathogenic bacteria to avoid infection.

An enzyme in tears, saliva and stomach acid that kills bacteria.

Traps microbes in inhaled air. Passes up the trachea for swallowing and destruction in the stomach.

• Blood clotting • White blood cells called phagocyted kill invading microbes in phagocytosis

Raised temperature is unfavourable to microbes and increase in blood flow delivers phagocytes to the area.

Something that prevents the growth of bacteria

A drug that kills bacteria

• Inhibits the enzyme that create amino acid cross links to strengthen the cell wall. Thus weaking it and causing osmotic lysis. Gram negative bacteria have the lipopolysaccharide layer proteting them from penicillin

They have no metabolic pathways

Acts as a competitive inhibitor of the second anticodon binding site in bacterial ribosomes preventing the tRNA molecules from binding to its complementary codon. Thus protein synthesis cannot occur.

• Stem cells in bone marrow produce B lymphocytes that mature in the spleen and lymphnodes. Each had specific receptors for a complementary antigen. • Contact with the antigen causes rapid mitosis to form antibody secreting plasma cells in a process of clonal expansion. This is increased further by the cytokines (T helper cells) from the cell mediated response. • Memory cells are produced whrn b lymphocytes differentiate and remain in circularion dividing rapidly when the antigen is encountered again.

• Stem cells in the bone marrow produce T lymphocytes which are activated int eh thymus gland. • Antigens are engulfed and expressed on the surface of the phagocyte. The T- lymphocytes undergo clonal expansion and differentiate. • T killer cells cause lysis of target cells. T memory cells remain in blood stream. T helper cells release cytokines which stimulated phagocytosis and the production of B lymphocytes.