4.1.1 Communicable Diseases, Disease Prevention And The Immune System Flashcards
What is a communicable disease?
A disease which can be passed between organisms and are caused by pathogens
What are examples of communicable disease?
Bacteria:
TB- damages lungs ans suppresses immune system in humans, cows, pigs and badgers
Meningitis- damages membranes in brain and can cause blood poisoning in young children
Virus:
HIV- destroys the immune system in humans and primates
Influenza- kills ciliated epithelial cells in airways of mammals
Fungus:
Athletes foot- crackling or scaling of skin between toes
Ringworm- circular red rash in mammals
Protoctist:
Malaria- damages red blood cells, hepatocytes and brain cells
What are each Pathogens mode of infection?
Bacteria- release toxins to damage body cells
Viruses- use host cells to reproduce before busrting out, destroying through host
Protoctista- take over cells and break them open
Fungi- digest living cells to destroy them, can also produce toxins
What are factors which can increase transmission?
Living conditions- overcrowding increases direct transmission
Climate
Social- lack of health care and health education
What are examples of vectors?
Animals: pests like mosquitos, water, food and wind
Plants: wind, water, animals and humans
What are the physical defences in plants?
Waxy cuticles create a barrier to entry
Cell walls provide another barrier
Callose is deposited into plasmodesmata to prevent spread of Pathogens
What are the chemical defences in plants?
Produce natural insects repellants to reduce herbivory (also reduces risk of disease from vectors)
Release of antibacterial substances which can kill or inhibit their growth.
Can produce toxins which break down into cyanide
Can trigger leaf absission to remove parts infected
What are the non-specific defences in humans?
Skin- physical barrier to block entry of Pathogens. Has sebum, an oily layer containing antimicrobial and flora which can outcomepete pathogenic organisms
Mucous membranes- secrete mucous to trap Pathogens, use lysosymes to digest and are wafted away by ciliated
Expulsive reflexes-expel foreign objects from airways or gut (coughing, sneezing, diarrhea or vomiting)
Blood clotting- scab forms from collagen fibres and fibrinkgen fibres and platelets to block entry.
Inflammation- cytokines released increasing permeability of blood vessels, leak tissue fluid causing swelling, isolates pathogens
What are antigens?
Unique molecules on the surface of cell membranes, allows immune system to distinguish between self or foreign cells
What is phagocytosis?
Engulf and digestion of Pathogens done by phagocytes
Neutrophils and macrophages
What are cytokines?
Molecules released by phagocytes and other cells, causes chemotaxis which trigger movement of other white blood cells to the area, increase body temperature to prevent pathogen reproduction.
What are opsonins?
Bind to pathogens, for easier recognition by phagocytes, acting as markers
What are the different t cells?
T helper- receptors on surface to bind to complimentary antigens on antigen presenting cells, produce interleukins to stimulate B cells
T killer- kill abnormal foreign cellsby producing perforin, puts holes in cell surface membrane causing cell death
T memory- provide long term immunity against specific pathogens for a rapid response during re infection
What is the humoural response?
Involves B lymphocytes and antibodies found in bodily fluids (humours)
Antibodies on membrane bind to complimentary antigens becoming apcs
Cloned selection, b cell with correct antibody is activated by t helper cell
Once b cell is activated, it undergoes clonal expansion to become memory or plasma b cells
What are the different types of B cells?
Plasma- secrete antibodies against specific antigens and have a short lifespan
Memory- provide long term immunity with a longer lifespan and rapidly divide to plasma cells when reinfected.
What is the primary response?
Body exposed to pathogen for the first time, slow and symptoms are experienced
Longer lag phase, slow incline for antibody increase, takes time for b cells to divide into plasma cells
What is the secondary immune response?
Exposed to the same pathogen, faster and no symptoms.
Shorter lag phase, antibody number increases quickly, fast division into plasma cells from memory cells
What is an autoimmune disease?
Immune system cannot correct identify ‘self’ antigens, so will attack its own body cells
Type 1 diabeties- attacks beta cells in islets of langerhans
Lupus- attacks connective tissues causing inflammation
Rheumatoid arthritis- attacks cells in joints to cause pain and inflammation
What are antibodies?
Y- shaped glycoproteins.
Have a constant region, variable region andhinge region
Constant region binds to receptors on cells
What are the methods antibodies use?
Agglutination- causes pathogens to clump together, makes easier for phagocytosis (multiple engulfed at once)
Opsonins- act as marker as it binds to antigens for easier recognition
Neutralisation- antitoxins bind to toxins from pathogens to prevent them from damaging cells.
Binding prevention: blocks cell surface receptors needed to bind to bind to host cells, so cannot bind or invade host cells
What is active immunity?
Immune response activated, own antibodies are made. Creates long term immunity as memory cells are produced.
What is passive immunity?
No immune response is triggered, no long term immunity
What is a vaccination
Stimulates body to produce an immune response to pathogen to develop artificial immunity.
Safe to prevent symptoms of disease so isolated antigens or weakened pathogens used
How does a vaccinations work?
Vaccine injected into blood
Stimulates primary immune response to produce antibodies
Memory cells produced
Re exposure causes memory cells to undergo clonal expansion to produce plasma cells
Plasma cells rapidly produce antibodies against the pathogen
Pathogen destroyed before symptoms
