Communicable Diseases, Disease Prevention And The Immune System Flashcards
How do bacteria cause disease?
- Produce toxins
- Can interfere with enzyme reactions
What is an example of an animal bacterial disease?
- Tuberculosis
- Damages lung tissue
What is an example of a bacterial plant disease?
- Ring rot
- Potato, tomatoes
- Damages leaves to stop photosynthesis
How does a fungi cause disease?
- Produce toxins
- Digests cells (saprophytic)
What is an example of a fungal animal disease?
- Athlete’s foot
- Fungi found in warm, moist areas of foot (between toes)
- Digests skin and cells there causing itching
What is an example of a fungal plant disease?
- Black sigatoka
- Damages leaves
- Causes black lines across leaves
- Destroy chloroplast so they can’t do photosynthesis
How do viruses and protists cause disease?
- Hijack cells to reproduce
- Inject genetic material into host cell
- Genetic material combines with host cell DNA
What is an example of a viral animal disease?
- AIDS
- T helper cells are targeted and destroyed so they can’t send signals to the rest of the immune system
- Body can’t defend itself against other pathogens
What is an example of a viral plant disease?
- Tobacco mosaic virus
- Causes discolouration
- Chloroplasts destroyed so lack of photosynthesis
What is an example of a protist animal disease?
- Malaria
- Transported by a vector (female mosquitos)
- Protist reproduces inside mosquito and is transported as mosquito feeds off human blood
- Protist reproduces in human cells
What is an example of a protist plant disease?
- Potato blight
- Damages leaves
What are examples of direct and indirect transmission in animals?
- Direct contact
- Inoculation (wound)
- Ingestion
- -
- Fomites (inanimate objects an individual comes into contact with)
- Droplet infection
- Vectors
What are examples of direct and indirect transmission in plants?
- Direct contact
- -
- Vectors
- Contaminated soil
What are 4 factors affecting transmission rate?
- Hygeine
- Weak immunity (animals)
- Overcrowding
- Genetic variation (plants)
What are some examples of a primary defence?
Barrier - skin
Chemicals - mucus and lysozymes and blood clotting
Describe the process of blood clotting
- Blood platelets release chemicals thromboplastin and serotonin to enhance clotting
- Thromboplastin is an enzyme that triggers a cascade of reactions resulting in the formation of a blood clot
- Serotonin makes smooth muscle in the walls of the blood vessels contract, so they narrow and reduce the blood supply to that area
- Epidermal cells grow below the scab, sealing it permanently
Name and describe secondary non specific immune responses?
Inflammation - Immune response at vascular tissues when infected
- Mast cells release histamines and cytokines
- Histamines dilate blood vessels which cause localised heat to reduce pathogen reproduction and redness.
- Cytokines are for cell signalling, and they attract phagocytes for phagocytosis
What are the two types of phagocytes?
Neutrophil - Lobed nucleus
Macrophages - Circular nucleus
Outline the process of phagocytosis
- Macrophage contains lots of lysosomes and has a receptor on its surface
- Receptor recognises antigens
- If an antigen is foreign, the macrophage engulfs the pathogen, forming a phagosome
- Lysosomes fuse with phagosome forming phagolysosome, and the lysozymes can then digest the pathogen within
- Pathogen is digested, apart from antigens on surface, so MHC’s bind to them, sending signal to other white blood cells
- Macrophage becomes an antigen presenting cell
What do opsinins do in phagocytosis?
Tag pathogens to allow them to be recognised more easily
Where are T and B cells made and matured?
T - Made in bone marrow but matured in thymus
B - Made and matured in bone marrow
What to T helper cells do?
- CD4 receptors bind to MHC complex on antigen presenting cell
- Release interleukins stimulate B cells and macrophages
What to T killer cells do?
- Destroy cells by releasing perforin
- Makes holes on cell surface membrane
What do T regulator cells do?
- Supress immune system, acting to control and regulate it
- Interleukins are important here
What to T memory cells do?
- Part of immunological memory
- Rapid secondary response therefore
What do B plasma cells do?
- Short lived
- Produce antibodies
What do B effector cells do?
- Divide to form plasma cell clones
What is cell mediated immunity simply?
- T lymphocytes respond to altered cells (APC, cancer, viruses)
- T cells will differentiate into different types of T cells to directly destroy altered cells
Outline the process of cell mediated immunity
- Macrophage becomes an APC with antigen-MHC complex in the same way as in phagocytosis
- CD4 receptor on T helper binds to complex on APC to recognise the attack
- T helper cells release interleukins to alert other cells of the attack and proliferate to make T memory and killer cells
- Interleukins also stimulate B cells to divide into plasma cells to make antibodies in humoral response, or stimulate phagocytes to do more phagocytosis
What is humoral immunity briefly?
- B lymphocytes respond to antigen and make specific antibodies
- B lymphocytes can respond to APC’s or pathogens directly
Outline the process of humoral immunity
- Lots of different shaped antibodies on the B lymphocyte surface
- Complementary shaped antibody to pathogen binds to the pathogen and engulfs it - known as clonal selection
- Becomes B-APC
- T helper cells recognise this APC and become activated, releasing interleukins to signal for further actions
- B-APC divides into plasma cells to make lots of specific antibodies and memory/plasma cells to prepare for secondary response - Clonal expansion
In what ways can a pathogen damage a plant?
- Releasing chemicals into plant cells like toxins
- Digesting cell walls
What is the role of callose in plant defence?
- Blocks plasmodesmata
- Deposit itself along cell wall so pathogen can’t enter cell
- Blocking phloem sieve plates, preventing pathogens travelling elsewhere in the plant
What is the role of lignin in plant defence?
- Chemical found in cell walls of xylem and other cells to prevent further entry of pathogen
What are some chemical defences in plants?
- Insect repellents
- Insecticides
- Antibacterial/antifungal chemicals
What is an autoimmune disease and give 3 examples?
- When the immune system stops recognising self cells and starts to attack healthy body tissue
- Type 1 diabetes
- Arthritis
- Lupus
Describe and give examples of active natural immunity
- Memory cells produced by immune system
- Can recognise antigen on pathogen and destroy it
- Humoral response
Describe and give examples of active artificial immunity
- Body is stimulated to make its own antibodies
- Injected dead pathogen
- Vaccination
Describe and give examples of passive natural immunity
- New born baby is given antibodies while still in uterus
- Lasts until the body can make its own antibodies
- Antibodies in breast milk/placenta
Describe and give examples of passive artificial immunity
- Antibodies can be formed in an animal, extracted and injected into a humans bloodstream
- Only temporary immunity but can be life saving
- Anti venom, needle stick injections
