Communicable Diseases Flashcards
Pathogens
Organisms that cause disease
-they live in organisms called hosts
-bacteria, viruses, fungi, protocists
Bacteria
Produce toxins and cause cell damage
-cocci (spherical)
-bacilli (rod shaped)
-vibrio (curved)
-spirilli (spiral)
Divide by binary fission
Problems with quick spreading bacteria
-food spoilage
-spread of disease
Virus
Virus attaches to host cell
-genetic material injected into host cell
-causing host cell makes new virus
-host cell splits open releasing new virus
Fungi
fungus send out specialised reproductive hyphae which grow. To the surface of the skin to release spores
-causes redness and irritation
Protoctista
These organisms cause harm by entering host cells feeding on the contents as they grow
-unicellular & have nucleus
eg amoeba and plasmodium
Types of viruses
HIV (animals)
tobacco mosaic virus (plants)
Types of bacterial infections
Tuberculosis (animals)
Ring rot (plants) - ring of decay
Types of fungal infections
Athletes foot (humans) - growth under skin of feet
Black sigatoka (bananas)
-leaf spots
Types of protoctists
Malaria (humans)
-headache, fever
Blight (tomatoes)
Direct transmission
-physical contact
-faecal oral transmission
-droplets in air or water
-transmission by spores in soil
Indirect transmission
Pathogens transmitted by a vector
eg mosquito bite passes malaria pathogen on
Factors affecting transmission
-over crowding
-poor ventilation
-poor health
Physical Plant defences
Cellulose cell wall-barrier
Lignin-waterproof
Bark-contains chemical defences
Stomata closure- prevents entry for pathogens
Chemical plant defences
Plant tissues contain chemicals that have anti pathogenic properties
-terpenoids
-phenols
-alkaloids
Necrosis
Deliberate cell suicide
-saves the rest of the plant
-stops further spread of infection
Blood clot
Damaged tissue exposes collagen and releases clotting factors ➡️
platelets activated by damaged tissue ➡️temporary plug formed
➡️thromboplastin (enzyme) catalyses prothrombin catalysed to thrombin (enzyme)
➡️fibrinogen (soluble) —> fibrin (insoluble) mesh of fibres
human primary defences
Skin- barrier
-reflexes (coughing, sneezing)
-nose (hairs)
-eye contains lysozymes kill pathogens
-clilia- mucus traps microbes
ciliates cells waft to throat to swallow(hcl)
human secondary responses
opsonins- protein molecule that attaches to antigens on pathogen surface -helps phagocyte bind
-phagocytosis
-Lymphocytes
-Fever and inflammatory response
Vaccines
Intentional exposure to a pathogen to be IMMUNE
-harmless or attenuated (weakened) version
HIV
Retrovirus
HIV replication-single stranded RNA instead of DNA
-reverse transcriptase enzyme uses RNA as template to make single strand DNA
-DNA polymerase makes double stranded DNA
-Attached to host DNA
-Host cell makes new virus
Types of vaccination
Herd - all/most of population are provide with immunity preventing spreads
Ring- all the immediate vicinity of the outbreak get vaccinated
Active immunity
active - your immune system makes its own antibodies after being exposed to antigens
Passive immunity
Antibodies are made by another organism can be achieved naturally or artificially
Why do we need new drugs
Antibiotic resistance -MRSA
-if you don’t finish course still traces of virus/pathogen that can mutate
How does HIV affect immune system
HIV turns into aids
-affects T helper cells
-won’t produce plasma cells & antibody
-weaker immune system
Cellular response
-the T cells & other immune system cells they react with eg phagocytes
Humoral response
B cells, clonal section and production of monoclonal antibodies
antigen exposure
⬇️
engulfed by Macrophage
⬇️
becomes antigen presenting cell
⬇️
B cell⬅️helper T Cell➡️cytoxic T cell
⬇️ ⬇️ ⬇️
Plasma Memory helper Active
cells. T cell. Cytoxic T
⬇️. 2nd ⬇️.
Memory B cells. Memory T cells
Roles of the cells produced in immune response
T helper cells- release cytokines that stimulate the B cells to stimulate phagocytosis
T killer cells- attack and kill host body cells that have antigen
T memory cells - provide long term immunity
T regulator cells - shut down immune response after pathogen removed
phagocytosis
phagocyte recognises the antigens
-cytoplasm of phagocyte moves round the pathogen to engulf it
-lysosome containing digestive enzymes fuses with phagosome
-enzymes break down pathogen
neutrophils
type of phagocyte
-first responders to cytokines(proteins)released by cells at site of a wound
-multilobed nucleus
-made in bone marrow
antibodies
composed of 4 polypeptide chains, which are linked together by disulphide bridges
-constant region- phagoctye interaction
heavy chain-middle
light chain at sides
antibiotics
kill bacteria and stop growth
-bacterial antibiotics- kill bacteria by destroying their cell wall (burst)
-bacteriostatic antibiotics- inhibit the growth of bacteria, stopping protein synthesis
T- cell clones
killer T cell- destroys antigens
Helper T cell- stimulates T & B cells
suppressor T cells- inhibits T & B cells
Memory T cells- remembers antigens for future encounters
