33. Defence System Flashcards
Human Defence system function
Defends and fights against pathogens
Pathogen def.
A disease causing organism
Immunity def.
Ability to resist infection
Characteristics of general immunity
- Doesn’t produce any antibodies
- Non specific- acts on all pathogens
- Defends by stopping entry and attacking
Methods of general immunity
Barriers
- Skin-physically stops pathogens entering, has sebaceous glands which secretes sebum to kill bacteria
- Platelets prevent entry of pathogens if skin is broken by clotting the blood and forming a scab.
- Tears, Sweat and Saliva-enzyme lysozome attacks bacteria walls
- Acid- HCL in stomach kills pathogens
Methods of general immunity
Attack-WBC
- WBCs called phagocytes and monocytes carry out phagocytosis-where pathogen is engulfed by monocyte/phagocyte and killed
Methods of general immunity
Attack- Proteins
- Complement:produces holes in wall of pathogen causing it to fill with fluid and burst. (complimentary wafer thin mint-bursts)
- Inferon: Makes cells surrounding infected cell immune to viral pathogen, stopping spread of pathogen.
Methods of general immunity
Inflammatory response
Infected cells release chemicals causing capillaries to dilate, causing swelling, redness, heat.
Attracts WBCs to the area resulting in further inflammation and heat, restriction of reproduction of bacteria and viral cells as environment doesn’t support bacterial and viral growth.
Specific defence system def.
Part of our immune system that attacks particular pathogens
Specific defence system characteristics
Produces antibodies.
WBCs attack the pathogen
Attacks particular/specific pathogens
Antibody
biomolecule
produced by
attacks what
biomolecule: protein
produced by: lymphocyte
attacks antigens
Antigen def.
(g for germ)
Antigens are any foreign molecule that stimulates the production of antibodies.
eg. Bacterial cell walls, viral coats, foreign cells, cancerous cells
Specific defence system
Monocyte-how it defends
- Recognises and engulfs antigens-phagocytosis, develops into phagocytes/macrophages
- Displays these antigens on its surface stimulating antibody production
SDS Lymphocytes- T-type Where produced and matured types Once activated go to
Produced: Bone marrow
Matured: Thymus
Types: 4 (helper, killer, memory, suppressor)
Once activated go to: Lymphatic system
SDS Lymphocytes- B-type Where produced and matured types Once activated go to
Produced: Bone marrow
Matured: Bone marrow
Types: 2 (plasma, memory)
Once activated: Lymphatic system
SDS
B lymphocytes types
- Plasma: Meets antigen, produces antibodies, which attach to antigen, antigen now recognisable and can be killed by T-cells or Monocytes
- Memory: plasma cells that dont take part in the first defence. Remain in body to recognise the antigen if it reenters the body, allowing it to react quicker.
SDS
T lymphocytes
- T-helper: Stimulate the production of B cells and T killer cells
- T-killer: secrete chemical perforin causes pores on antigen, causing water to enter and it bursts.
- T-Suppressor: Stops immune response after pathogen destroyed. Prevents over reacting
- T-memory: Form during first response but stay in body, intercept antigens quicker and provide quicker response.
Induced Immunity def.
Ability to resist infection by the production of antibodies to specific antigens
Explain passive (induced) immunity
Has not been affected by the pathogen/antigen
Individual is given antibodies produced by another organism
Explain Active (induced) immunity
Has been infected by pathogen/antigen
Production of ones own antibodies to an antigen that has entered their body.
Example of natural and artificial passive immunity
Natural: Baby given antibodies from breastmilk
Artificial: given antibodies by injection
Example of natural and artificial active immunity
Natural: When pathogen enters body and individual produces antibodies in response.
Artificial: When a pathogen is medically introduced into the body- given vaccination
Vaccination def.
Non disease causing dose of pathogen which stimulates the production of antibodies
Organs specific to Immune system
Tonsils
Thymus
Lymph node
Spleen
Antibody def.
Protein produced by lymphocytes in response to an antigen