disease Flashcards
define health
free from disease
physical & mental & social well being
good nutrition
suitably housed
define disease
condition that impairs normal functioning of the body
departure from good health caused by malfunction of mind or body
define pathogen
organism that causes disease
define parasite
organism that lives on another organism and causes harm to host organism
lives on host for:
- nutrition
- means of transmission
- warmth
- protection
define symptoms
caused by the damage done to cells by pathogens or the toxins they produce
give a synopsis of tuberculosis (TB)
BACTERIA
pathogen - myobacterium tuberculosis
effects- destroys lung tissue and suppresses the immune system
cure - vaccine
6 month course of antibiotics
BUT antibiotic resistant strains emerged
give a synopsis of bacterial meningitsis
BACTERIA
pathogen - strepcoccus pneumoniae
symptoms - fever with cold feet and hands
confusion and irritability
severe muscle pain
distinctive rash
sensitivity to light
cure - vaccine and intravenous antibiotics
give a synopsis of ring rot
BACTERIA
pathogen - clavibacter michiganesis
effects- damage leaves, tubers & fruits
destroy 80% of crop
cure - none
wait 2 years
give a synopsis of HIV/AIDS
VIRUS
effects- destroys T helper cells, gradually destroying immune system leaving patient vulnerable to infection
treatment - NO CURE
antiretroviral therapy (ART)- combination of HIV medicines which control the infection
prevention - sex education, screening for blood, test for HIV
give a synopsis of influenza
VIRUS
pathogen - orthomyoxoviridae spp.
effects - infects ciliated epithelial cells and kills them leaving airways open for secondary infection
cure - NONE
but controlled by a vaccine
give a synopsis of tobacco mosaic virus
VIRUS
affects - tobacco plants (tomatoes, peppers, cucumbers, petunia, delphinius
effects - damaged leaves, flowers and fruit
stunted growth and reduces yield
cure - NONE
but resistant strains
give a synopsis of black sigatoka
FUNGUS
pathogen - mycosphaerekka fijiensis
effects - destroys leaves ,, hyphae penetrates and digests cells
prevention - resistant strains and fungicides
give a synopsis of ring worm
FUNGUS
effects - causes grey-white, crusy infectious circular areas of the skin
doesn’t cause much damage but is itchy
cure - antifungal cream
give a synopsis of fungal foot
FUNGUS
pathogen - tinia pedia
effects - grows on and digests moist skin between toes
causing crackling and scaling which is itchy and sore
cure - antifungal cream
how are pathogens and parasites spread
food and water
insect bites
airborne droplets
indirect contact
direct contact
define transmission
the means by which communicable diseases are spread from one organism to another
give examples of direct transmission
direct contact (kissing)
inoculation (break in the skin)
ingestion (eating contaminated food)
give example of indirect transmission
fomites (inanimate objects)
droplet infection
vectors
spores
how does povert affect transmission of disease
less primary health care
malnutrition leads to weakened immune system (can’t make antibodies)
poor hygiene
how do social factors affect transmission of disease
sexual attitudes
availability of condoms
how do living conditions affect transmission of disease
crowding increases the spread of droplet infection to multiple people in a small zone
define epidemiology and explain how it helps people for health
identifies the cause(s) of a disease and determines and predicts its spread
provides help where it is needed most including vaccination programmes
name 6 non-specific defenses
skin
expulsive reflexes
blood clotting
wound repair
mucous membranes
(ciliated epithelium)
inflammation
define an antigen
molecule on the surface of an organism which is recognised by an antibody
what are phagocytes
non-specific that attack any invading pathogen regardless of its antigens
what do macrophages do?
antigen presentation
partially digest pathogens and expose their antigens on their c.s.membrane to initiate the immune response
what do cytokines do?
released by macrophages and signal to phagocytes to the site of infection (cytotaxis)
have a specific shape to bind to receptors on c.s membrane of target cells
responsible for fevers
what do opsonins do?
proteins that bind to pathogens making them easier to be recognised by phagocytes
what are the differences between macrophages and neutrophils
neutros make a significant proportion of WBC
neutros have a multi-lobed nucleus
macrophages have spherical nucleus
neutrophils completely digest the pathogen and die
macrophages partially digest pathogen
describe inflammation
localised response characterised by redness, swelling, heat and pain
describe how the skin defends the organism from a pathogen
keratinised layer of deal skin cells acts as a physical barrier
sweat is antimicrobial (lowers pH)
how does blood clotting occur
platelets come in contact with collagen
why is clotting important
platelets release substances
via a cascade, forms fibrin which forms a network trapping platelets and forms a scab
which prevents the pathogens from entering through a cut
describe the ‘cascade’ to form a blood clot
thromboplastin
(& cofactor Ca2+)
and prothrombin form thrombin
thrombin causes the fibronogen to form fibrin which forms a clot
what happens under a scab
epidermal skin cells divide by mitosis
damaged blood vessels regrow
when new epidermis reaches normal thickness, scab sloughs off
describe inflammation
histamine released by mast cells and cause arterioles to dilate
makes the blood vessels leaky
cytokines attract WBC
describe a fever
cytokines signal to the hypothalamus to raise the set point
body’s thermoregulatory set point is raised above normal body temperature
describe the stages of the humoral response
antigen presentation
B cell with correct antibody is selected for cloning (clonal selection)
Clonal expansion by mitosis
differentiation of the B cells into:
- B-memory cell
- plasma cell
describe the stages of the cellular response
antigen presentation
T cell with correct antibody is selected (clonal selection) then this cell divides by mitosis (clonal expansion)
then differentiates to form:
- T-memory cells
- T-killer
- T-helper
describe the structure and function of T-helper cells
have CD4 receptors which bind to the surface antigens of APCs
produce interleukins which:
- stimulates macrophages
- stimulates the production of other T-cell
- stimulates the activity of B cells to increase antibody production
describe the function of T-killer cells
destroys pathogen with specific complimentary antigen
produces perforin which kills the pathogen by making holes in the c.s.m to make the membrane permeable
describe the function of T-memory cells
remain in body for long term immunity
recognises the same antigen from pathogen entering body causing a secondary response
divides and differentiates into plasma cells
which produce antibodies at a quicker rate
describe the function of T-regulatory cells
suppress immune response once the pathogen is eliminated
makes the body recognise self-antigens
describe the function of plasma cells
have a short lifespan
produce antibodies to particular antigen
produces 2000 antibodies per second while it is active
what is the difference between B cells and T cells
B cells mature in the bone marrow
T cells mature in the thymus gland
what is cell-mediated response important against
viruses and early cancer
how does cell-mediated response occur
T cells respond to cells that have changed in some way
how does humoral response occur
body responds to antigens outside the cells ( >bacteria >fungi)
produces antibodies soluble in blood and tissue fluid and aren’t attached to cells
how are APCs formed
a B cell with a complementary antibody binds to a pathogen’s antigen, engulf the pathogen and process it to become an APC
what are examples of physical barriers in plant defence
bark
cellulose cell wall
waxy cuticle of leaves
how do plants deal with diseased areas
seal it off and sacrifice it
get replaced by meristems
how does callose provide a physical defense against pathogens in plants
contains beta-1,3 and 1,6 linkages between monomers
callose is deposited between cell walls and the cell membrane in cells next to infected cells
callose papillae act as barriers
prevents pathogen entering the plant cells around the site of infection
callose blocks sieve plates and plasmodesmata to prevent spread of pathogens
describe the effect of chemical defences on pathogens in plants
chemicals repel the vectors of disease or kill invading pathogens
give example of chemicals produced by plants for defence against pathogens
insect repellent
insecticides
antibacterial compounds
antifungal compounds ( >chitinase)
anti-oomyctes (>glucanases)
general toxins
