4.1 Communicable Diseases, Disease Prevention And The Immune System Flashcards
What are the different types of pathogens?
Bacteria, virus, fungi, protoctista
What diseases are caused by bacteria?
Tuberculosis (TB) and ring rot (tomatoes and potatoes)
What diseases are caused by viruses?
HIV/AIDS, influenza, tobacco mosaic virus
What diseases are caused by fungi?
Black sigatoka, athletes foot
What diseases are caused by protoctista?
Malaria, late blight
How are pathogens transmitted?
Vectors, spores, living conditions e.g. climate, social factors
What are vectors?
Organisms that pass the pathogen to humans
What are spores?
Small reproductive structures dispersed into the environment via wind and water.
What are physical plant defences?
- waxy cuticle on leaf epidermis
- Cellulose cell wall
- Callose deposition following pathogen invasion
Name chemical plant defences
Production of antibiotic/ fungicidal compounds, production of insecticides
What are primary, non specific defences in animals?
Skin, wound repair, blood clotting, inflammation, mucous membranes, expulsive reflexes
Describe wound repair
- Outer layer of skin cells divide and migrate to edges of wound
- Tissue below contracts bringing edges of wound together
- Fuse edges by formation of collagen fibres
Describe blood clotting
Platelets release substances
Cascade of events
Formation of fibrin
Fibrin network traps platelets forming clot
Describe inflammation
Swelling of tissue isolates pathogens
Vasodilation increases blood flow to the area helping white blood cells arrive
Describe phagocytosis
Receptors bind to antigens on pathogen, phagocyte cytoplasm extends - engulf, pathogen contained in phagosome, lysosome fuses with phagosome = phagolysosome, lysozymes digest pathogen and destroy it, digested pathogen removed by exocytosis, antigen molecules displayed on surface
What are cytokines?
Cell signalling molecules to attract WBC’s to site of damage
What are opsonins?
Bind to + tag foreign cells making phagocytosis more likely
T lymphocyte activation
- Specific shape receptors -> bind to complementary antigens on APC or pathogen
- Clonal selection
- Divide by mitosis - clonal expansion
- T helper, T killer, T regulatory, memory cells
Role of T helper cells
Release interleukins to activate lymphocytes
Role of T killer cells
Destroy cells infected with the pathogen
Role of T regulatory cells
Suppress other immune system cells to prevent them attacking host cells
Role of T memory cells
Remain in blood for secondary response
B cells
B lymphocytes activated/ clonal selection, divide by mitosis/clonal expansion, produce B plasma and B memory cells
Role of plasma cells
Produce antibodies with a complementary shape to the antigens
Describe the secondary response
Faster
Larger
Shorter duration
Role of anti-toxins
Antibodies can bind to toxins released by pathogens and neutralise them making them harmless
Role of agglutination
Clumps pathogens immobilising them making phagocytosis more likely
Describe active immunity (including natural and artificial)
Body makes own antibodies
Natural: Catch a cold
Artificial: Vaccination
Describe passive immunity
Ready made antibodies
Natural: breast feeding
Artificial: antibody injection
Define autoimmune disease
Immune system fails to distinguish between self and foreign antigens so attacks body cells which are supposed to be there (e.g. rheumatoid arthritis)
Describe rheumatoid arthritis
Immune system attacks cells in joints causing pain and inflammation
What are sources of medicine?
- Plants and microorganisms
- must maintain biodiversity to protect soueces
