4.1 COMMUNICABLE DISEASES Flashcards
What is a pathogen?
a microorganism that causes disease.
What are the characteristics of Tuberculosis?
a disease that affects many parts of the body, killing the cells and tissues; the lungs are most often affected.
What organism causes Tuberculosis?
bacteria: Mycobacterium tuberculosis and M. bovis.
Define direct transmission.
passing a pathogen from host to new host, with no intermediary.
Define indirect transmission.
passing a pathogen from host to new host, via a vector.
Define transmission.
passing a pathogen from one host to another.
What is meant by the term passive defence?
This is a defence present before infection, and its role is to prevent entry and spread of a pathogen. Passive defences include physical barriers and chemicals.
What is meant by the term active defence?
When pathogens attack, specific chemicals in their cell walls can be detected by the plant cells. These chemicals include specific proteins and glycolipids. The plant responds by fortifying the defences already present. This includes increasing the physical defences and producing defensive chemicals.
Define inflammation.
swelling and redness of tissue caused by infection.
Define mucous membrane.
specialised epithelial tissue that is covered by mucus.
Define primary defence.
those that prevent pathogens entering the body.
What is an antigen-presenting cell?
a cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system.
What is meant by the term clonal selection?
selection of specific B or T cell that is specific to the antigen.
What are cytokines?
hormone-like molecules used in cell signalling to stimulate the immune response.
What are antibodies?
specific proteins released by plasma cells that can attach to pathogenic antigens.
What are B memory cells?
cells that remain in the blood for a long time, providing long-term immunity.
What is meant by the term clonal expansion?
an increase in the number of cells by mitotic cell division.
What are agglutinins?
antibodies that cause pathogens to stick together.
What are anti-toxins?
antibodies that render toxins harmless.
What are opsonins?
antibodies that make it easier for phagocytes to engulf the pathogen.
Define active immunity.
where the immune system is activated and manufactures its own antibodies.
Define artificial immunity.
immunity that is achieved as a result of medical intervention.
Define epidemic.
a rapid spread of disease through a high proportion of the population.
