Pathogens, antigens and allergens Flashcards
Pathogen
An agent that causes disease
Antigen
Any molecule that may trigger an immune response / activate immune system
Non self antigen
A molecule from outside the body that is recognised by the immune system and initiates an immune response. Also known as a foreign antigen
Major histocompatibility complex ( MHC ) proteins
A group of proteins present on the surface of all self - cells that enables the immune system to distinguish it from non - self material. Also known as self antigens
What are self antigens also called
Major histocompatibility complex 1
MHC I
proteins expressed on all nucleated cells of the body. Therefore most cells of the body minus RBC’S
MHC II
proteins are found on specialized cells of the immune system
Autoimmune disease
A disease in which an individuals immune system initiates an immune response against their own cells
Allergen
A non pathogenic antigen that triggers an allergic reaction
Allergic reaction
An over reaction of the immune system to a non pathogenic antigen
How does a virus infect a cell?
First they must link with host cell and inject DNA / RNA
attachment
penetration
biosynthesis of components
reassembly and lysis
Types of antigens
self antigens
non self antigens
allergens
Malfunctions involving self antigens/self-markers
self cells that set off the immune system.
Disease
Any change that impairs the function of an individual in some way.
Infectious Disease
A disease caused by a pathogen.
Infection
When the pathogen is present in/on the host.
Sterile
Free from pathogens
Types of pathogens
Cellular pathogens
Non cellular pathogens
Cellular pathogens
A pathogen that has a cellular structure and exhibits the processes of a living organism . Examples include bacteria, fungi, protozoa and parasites
Non cellular pathogens
A pathogen that neither has a cellular structure nor exhibits the processes of a living organism . Examples include viruses and prions
Prions
Are proteins that can reproduce on their own and can be infectious through consumption. They are abnormally folded proteins that can induce normal nearby proteins to become misfolded, Only occur in mammals and only affect brain. They do not contain nucleic acids
There are 2 forms of prions:
- PrP-sen (normal)
- PrP-Sc (disease causing)
Viruses
- An infectious agent composed of genetic material ( DNA / RNA ) inside a protein coat ( capsid )
- Viruses can cause disease through the lysis of cells during viral replication
- must infect a host before reproduction
Lysis
The disintegration or rupturing of a cell
Hyphae
Branching filaments of a fungus which help absorb nutrients from the environment
Parasite
An organism that lives in or on another organism, usually deriving nutrition from a host
Best treatment for viruses
vaccinations
How may bacteria enter humans
body contact
sexual contact
food and water
droplet or airborne
carrying vector
How does bacteria reproduce
binary fission
Treatment of bacterial infection
antibiotics
Fungi
Eukaryotic organism that secretes digestive enzymes into the environment. They include yeasts and moulds and contain long branching filaments called hyphae
Worms
multicellular invertebrate parasites. Can vary in length
Protozoa
Single celled eukaryotes that can be free living or parasitic/ They have many different mechanisms of action
