M4 C12: communicable diseases Flashcards
what is a disease?
a condition that impairs the normal function of an organism
What is a pathogen?
a microorganism that can cause disease
what are some types of pathogens?
bacteria, viruses, fungi, protoctista
what is a communicable disease?
disease that can be spread from person to person by a pathogen
what is tuberculosis?
bacterial disease can affect animals human/cattle
what is bacterial menigitis?
bacterial disease affects humans
what is ring rot?
bacterial disease affecting tomatoes/ potatoes
what is HIV/AIDS?
a virus affecting humans
What is influenza?
virus affecting animals/humans
what is tobacco mosaic virus?
virus affecting plants
what is black sigatoka?
fungus affecting banana plants
what is ringworm?
fungus affects cattle
what is athletes foot?
fungus affects humans
what is potato/tomato late blight?
a protoctist affecting potato and tomato plants
what is malaria?
a protoctist affecting animals including humans
what is direct transmission of diseases?
when disease is transmitted directly from one organism to another
what is indirect transmission of diseases?
via a intermediate such as air, water, food, vector
what is an example of a direct transmission of disease?
droplets in the air, intercourse, touching an organism. eg athletes foot or HIV
what is an example of indirect transmission of disease?
malaria is transmitted via mosquitoes
potato late blight is transmitted by spores between plants
what are 3 factors affecting transmission?
living conditions
social factors
climate
how does living condition affect transmission of diseases?
overcrowding increases disease as people are closer together eg TB stays in the air for a long time so confined space = increased risk
how does social factors affect transmission of diseases?
income, occupation and area increases risk for example increase risk of HIV when people have limited access to anti-HIV drugs or no education about how to stop HIV
how does climate affect transmission of disease?
affects the spread of disease. for example wet summers increases potato blight as spores need water to spread. malaria need tropical climates to reproduce to spread malaria
why do organisms need defences against pathogens?
pathogens need to enter an organism to cause disease. animals and plants have evolved defences to protect themselves against pathogens.
how is skin a defence against pathogens?
blocks against pathogens as a physical barrier. also secretes antimicrobial chemicals which destroy or slow growth of microorganisms e.g. lysosomes
how are mucous membranes a defence against pathogens?
protect the body openings that are exposed to the environment e.g. nose, mouth etc. some membranes secrete mucus to trap pathogens e.g. mucus lining the lung epithelium which traps pathogens.
how is blood clotting a defence against pathogens?
a mesh of protein fibres that plug wounds to prevent pathogen entry and blood loss. They are formed by chemical reactions in the body that take place when platelets are exposed to damaged blood vessels.
how is inflammation a defence against pathogens?
-the damaged tissue releases molecules to increase the permeability of the blood vessels, so they leak fluid into the surrounding areas. This causes swelling and isolates any pathogens that may have entered the damaged tissue.
- vasodilation increases blood flow to the affected area. This makes the area hot and brings white blood cells to the area to fight off any pathogens.
how is wound repair a defence against pathogens?
Skin is able to repair itself in the event of an injury and re-form a barrier against pathogen entry. The surface is repaired by the outer layer of skin cells dividing and migrating to the edges of the wound. The tissue below the wound then contracts to bring the edges of the wound closer together. It is repaired using collagen fibres.
how are expulsive reflexes a defence against pathogens
cough stems from irritation in the respiratory tract. Both coughing and sneezing are an attempt to expel foreign objects, including pathogen when they become irritated.
what are the physical defences of a plant?
waxy cuticle
cell wall
Callose gets deposited between plant cell walls and plasma membranes
what are some chemical defences of a plants?
Plants produce antimicrobial chemical which kill pathogens or inhibit their growth. Other chemicals secreted by plants are toxic to insects to prevent diseases spread by vectors
what is the immune response?
the body’s reaction to foreign antigens
what is an antigen?
molecules on surface of a cell
what happens when antigens are identified in the body?
activates the immune response
what is a non specific immune response?
same response for all microorganisms