The Defence System Flashcards
What is a pathogen?
A disease causing organism
Examples of pathogenic organisms include…
Some bacteria, fungi and viruses
Two lines of defence
- The general defence system
* The specific defence system
Antibodies are part of what system?
Specific defence system
What is part of the general defence system?
Skin Mucus Chemicals White blood cells Platelets
What is an antigen?
An antigen is a ‘foreign’ substance that causes a white blood cell to produce an antibody
Where are antigens found?
Antigens are found on the surface of pathogens and transplanted organs (eg. heart)
Where are antigens found?
On the surface of pathogens and transplanted organs
What is a lymphocyte?
A lymphocyte produces antibodies which attach to specific antigens
What is an antibody?
A protein made by white blood cells (lymphocyte) that recognises and attaches to specific antigen
What is a monocyte?
A monocyte engulfs a pathogen and destroys it
What is the process in which monocytes engulf pathogens?
Phagocytosis
What are memory cells?
Memory cells are made by your body when you make antibodies
What is the function of memory cells?
Memory cells speed up the response time when an invader of the same type returns in the future
What is immunity
Immunity is the protection against infection
What is induced immunity?
Induced immunity is protection against infection using antibodies
What are the two types of induced immunity
1) Active induced immunity
2) Passive induced immunity
What is active induced immunity
- you make the antibodies and the memory cells
- Can be natural (made during infection)
- Can be artificial (vaccination)
- Long-term
What is passive induced immunity
- antibodies given to you (you do not make antibodies or memory cells)
- short-term
- Natural (given to a child in the womb before birth or in breast milk after birth)
- Artificial (given by injection of antibodies example antitetanus)
What is immunisation
Immunisation involves giving a person a vaccination or an injection of antibodies to protect against infection
What is a vaccination
A vaccine is a dead or damaged pathogen that triggers antibody production
How do vaccinations work
Vaccination tricks lymphocytes into producing antibodies and memory cells so that if the real pathogen attacks in the future antibodies are produced very quickly to destroy it before It can do damage
How does the general defence system fight fever
- High temperatures denature enzymes in the pathogen
- The pathogen dies
Where are b-lymphocytes produced
In the bone marrow
What is the function of b-lymphocytes
To produce antibodies
Where are T-lymphocyte produced
In the bone marrow
Four types of T cells
Helper T cells
killer T cells
suppressor T cells
memory T cells
Function of helper T cells
Trigger the production of b cells and killer T cells
Function of killer T cells
They destroy
- virus infected cells
- tumour cells (cancer)
- foreign cells (this is why transplants are rejected)
Function of suppressor T cells
They switch off the immune response after the antigen (pathogen) has been destroyed
Function of memory T-cells
These remember the antigens
Autoimmune diseases
1) rheumatoid arthritis (where joints are attacked)
2) Multiple sclerosis MS (where the myelin sheet of nerve cells is attacked)
3) Psoriasis (where the skin is attacked)
What are allergies
Allergies occur when antibodies are made against material that should not be antigenic
Example of allergies
Hayfever (the body reacts to pollen which is harmless)
