Immunology - basis of infection and immunity Flashcards
What is a Eukaryote?
Organisms incl. animals, plants, fungi, protists and algae.
What are the features of a eukaryote cell?
Has a nucleus and other membrane bound organelles.
Can be single celled or multicellular.
What is a prokaryote?
Bacteria and archaea
What are the features of a prokaryote?
Lacking a nucleus and a lot of other organelles. Often have a cell wall and a simple chromosome.
Single cell mostly
What are Saprophytes?
Prokaryotes that feed on dead and decaying matter
What are symbionts?
Prokaryotes that live with another organism and mutually beneficial
What are commensals?
Prokaryotes that live in association with another organism, adversely affecting said host
What are parasites?
Prokaryotes that require a host and are detrimental to said host
How is a pathogen defined?
An organism that will cause disease to a host
What is virulence?
The severity of the disease
What is an obligate pathogen?
Also called a primary pathogen.
Infection is ALWAYS associated with the pathology aka if the organism is there the disease will be very likely present
What is an example of a primary pathogen?
Brucella abortus - causes abortion/premature births
What is an opportunistic pathogen?
Also known as a secondary pathogen.
it is found on the epithelium of an organism but isn’t a commensual. It will become pathogenic if the opportunity present e.g. if there is a break to the epithelia
What is an example of an opportunistic pathogen?
Mannheimia haemolytica (pasteurella) - the bacteria isolated from the respiratory disease in cattle and pneumonia in calves.
What are the routes of infection?
Direct/indirect contact (skin infections)
Aerosol (respiratory)
Oro-faecal (enteric)
Vector born (requires an intermediate or transport host)
Transplacental (vertical)
What is an exogenous site of infection?
Epithelial surfaces
e.g. skin, respiratory tract, GIT and urogenital tract
What is an endogenous site of infection?
Body tissue
e.g.
Intracellular - cytoplasm
Extracellular - tissue fluid
Vesicular - endosomes
What infects intracellularly?
Viruses
What infects extracellularly?
Most bacteria and helminth parasites
What infects vesicular?
Mycobacteria and some protozoan parasites
What are the immune cells of the blood and of the tissues?
White blood cells and macrophages respectively
What types of white blood cells are there?
Neutrophils, Eosinophils, Monocytes/macrophages and lymphocytes
What do neutrophils do?
Phagocytose bacteria
What do eosinophils do?
Kill parasites