The Defence System Flashcards
General defence system
Non-specific methods used to prevent the entry of pathogens into body and killing those that do
Pathogens
Diseases causing microbes
1st line of defence
Skin
Tears - lysozyme
Mucous membranes
Stomach acid
Blood clotting
Inflammatory reaction
Cause redness + swelling at site of infection
More white blood cells moving towards area to fight infection by phagocytosis
Complement protein
(Protein in blood)
Produces holes in wall of bacteria, causing it to fill up with liquid and burst
Interferons
(Protein in blood)
Makes cell resistant to virus so virus can’t spread
Phagocytic white blood cells
Chemicals that attract white blood cells are released when cells are damaged
White blood cells engulfs ad destroy any bacteria
Specific Defence System
Defence against pathogens using antibodies or particular white blood cells
Leads to developing immunity - ability to resist disease
White Blood Cells (Monocytes)
Develop into macrophages
Recognise antigens on surface of pathogen
When pathogens is digested, antigens from pathogens are displayed on surface of macrophage
Can leave blood vessels and engulf damaged / dead cell
Antigens
A foreign molecule that stimulates production of antibodies
Antibody
Protein produced by lymphocytes in response to an antigen
Antigen-antibody relationship
Each type of antibody is specific to a single antigen
Antibodies surround pathogens and cause them to burst by complement system
Cause pathogens to clump together
Lymphocytes
Produces antibodies
B cells
Mature in bone marrow
Adapted to recognise one specific antigen and produces one type of antibody
Plasma B cells
Produce large numbers of antibodies, circulate in lymph + blood
Memory B cells
Allow body to respond if same antigens enter
Effective in preventing infections
Produce antibodies
T lymphocytes
Produced in bone marrow
Matured in thymus gland
Helper T cells
Recognises antigens
Secretes interferons which stimulates production of B cells and killer T cells
Killer T cells
Kills abnormal cells and foreign cells
Release perforin, cause invading cell to become porous and burst
Suppressor T cells
Reduce immune response when invading antigen is destroyed
Memory T cells
Trigger B cells and killer T cells when the same antigen invades
Induced immunity
The ability to resist disease caused by specific pathogens by the production of antibodies
Active immunity
Immunity is built up by the human itself
Natural active immunity
When pathogen enters the body in the normal way
Build up own antibodies to fight infections
