chapter 12 - communicable diseases Flashcards
define disease
a condition that impairs the normal functioning of an organism. both plants an animals can get diseases
define pathogen
a (micro)organism that causes a disease - often called a microbe
what are communicable diseases
diseases that spread between organisms
what are the 4 types of pathogen
fungi, bacteria, protoctista (protista) and viruses
how do fungi cause disease
some fungi are parasitic so they feed off of living plants and animals. (saprophytic digestion)
produce millions of spores allowing them to spread rapidly throughout crop plants.
stop plants from photosynthesising
some fungi produce toxins which effect host cells
how do viruses cause disease
- virus attaches to cell
- viral DNA injected into cell
- viral components assembled, viral nucleic acid is replicated and proteins are synthesised
4.viruses released, death/ bursting of cell
how do bacteria cause disease
bacteria produce toxins that poison or damage host cells
either destroying cell membranes, cell walls or genetic information so the host cell cannot reproduce
what is the name for the collection of hyphae on fungi
mycelium
tuberculosis
organism effected:
pathogen type:
animals
bacterial
bacterial meningitis
organisms effected:
pathogen type:
humans
bacterial
ring rot
organism effected
pathogen type
potatoes and tomatoes
bacterial
HIV/AIDS
organism effected
pathogen type
humans
viral
influenza
organism effected
pathogen type
animals
viral
malaria
organism effected
pathogen type
animals
protoctist
late blight
organism effected
pathogen type
potatoes and tomatoes
protoctist
black sigatoka
organism effected
pathogen type
banana plants
fungal
ring worm
organism effected
pathogen type
cattle
fungal
athletes foot
organism effected
pathogen type
humans
fungal
what are examples of direct spread of disease
droplet infection (coughing or sneezing)
sexual intercourse
touching
what are examples of indirect spread of disease
intermediate eg. air, water, food, surfaces or another organism (vector)
what factors can effect the spread of disease
social :
overcrowding, poor health and nutrition
poor education of health , culture and infrastructure - some countries traditional medical practices can increase transmission
climate:
potato/tomato blight is most common in WET SUMMERS
malaria most common in TROPICAL COUNTRIES
how does climate change effect the spread of disease
results in changing environments which can lead to new vectors and disease in different areas
what are some physical plant defences
thick waxy cuticle: physical barrier + waterproof
cell wall - physical barrier + contains chemicals
callose - polysaccharide deposited between cell walls and membranes when plant is infected
prevents pathogens entering cells - blocks phloem sieve plates - stop spread of pathogen
what are some chemical plant defences
produce antimicrobial chemicals which kill or inhibit the growth of pathogens
e.g. saponins destroy the membranes of fungi
produce chemicals that are toxic to insect pests eg. vectors
what is the function of saponins in plants
destroy the membranes of fungi
define primary non-specific defence in animals
prevent initial entry of ANY TYPE of pathogen into an organism
what are some primary non-specific defences in animals
skin - physical barrier + secretes antimicrobial chemicals
nose hairs, eyelashes + tears - physical barrier
mucus - traps pathogens
wound repair - mitosis and migration of epidermal skin cells repair open wounds
blood clotting - platelets stop pathogens from entering + prevent blood loss
swelling - more tissue fluid drains into the lymphatic system
describe the primary non-specific defence of swelling in animals
histamines make the blood vessels dilate and more leaky more tissue fluid drains into the lymphatic system and heat raises
raised heat helps prevent pathogens reproducing
cytokines attract white blood cells to the site
define secondary non-specific defence in animals
once ANY TYPE of pathogen is already in an organism
why is the specific immune response quicker than the non-specific response in animals?
because the immune cells have to identify the specific pathogens that enter an organism
why is the secondary specific immune response faster than the primary?
because the secondary immune response already has memory cells which, when they come across the pathogen for the second time, are able to rapidly divide and form a large number of clones
what are helpful chemicals in non-specific defence
cytokines - act as cell signalling molecules informing other phagocytes that the body is under attack
can also increase body temperature and stimulate the specific immune system
opsonins - bind to pathogens and tag them so they can be more easily recognised by the phagocytes
what is an antigen?
a protein or glycoprotein that has a specific shape for organisms to recognise self-antigens and foreign antigens
what two responses do foreign antibodies trigger?
phagocytosis (secondary non-specific)
or
production of antibodies (specific)