4.1.1 communicable diseases and the immune system Flashcards
what is a pathogen
an organism that causes disease by taking nutrition from another organism or causing it harm
what does parasitic mean
organisms that live in or on a host and take their nutrition
what is fungi
eukaryotic
non-pathogenic
parasitic
release spores and multiply via budding
grow under skin
what is a virus
akaryotic (non-living)
uses cell’s nucleus to multiply
what is a protoctista
eukaryotic
non-pathogenic
parasitic
require a host
release toxic waste
what is bacteria
prokaryotic
non-pathogenic
multiply by binary fission
release toxic waste
what is tuberculosis
bacteria
kills cells and tissues and affects respiratory system
what is HIV/AIDs
virus
attacks immune system
what is influenza
virus
attacks respiratory system and causes muscle pain/headaches
what is tobacco mosaic virus
virus
discoloured leaves
what is blight
protist
affects leaves and potatoes
what is black sigatoka
fungus
leaf spots on banana plants that reduce yield
what is ringworm
fungus
growth in skin causes rash
what is athlete’s foot
fungus
growth under skin in feet
what is ring rot
bacteria
ring of decay in vascular tissue
what is malaria
protist
parasite in blood causes fever then death
what is bacterial meningitis
bacteria
infection of meninges (membranes around brain and spinal cord)
what is direct transmission
when communicable diseases are passed along by direct contact
what are examples of direct transmission
direct physical contact
faecal-oral transmission
droplet infection
spore transmission
what are the passive physical plant defences
cellulose cell wall
lignin thickening of cell walls
waxy cuticles
bark
stomatal closure
what is a callose
polysaccharide deposited in the sieve tubes to restrict entry of pathogens
what is a tylose
a swelling that fills xylem vessels that stops passage of water
what necrosis
cells are killed to prevent the spread of infection
what is a canker
produced by death of cambium creating a sunken lesion
what are the chemical plant defences
terpenoids
alkaloids
tannins
pheromones
hydrolytic enzymes
defensins
what does non-specific mean
fast acting
same for any infection
provides a general defense against most threats
what are the primary physical barriers
skin
mucous membranes
stomach acid
lysozymes
sebum
expulsive reflexes
how does skin act as a barrier
epidermis contains keratinocytes so when cells dry out the cytoplasm becomes keratin
how do mucous membranes act as a barrier
contain ciliated epithelium
how does stomach acid act as a barrier
acidic conditions and digestive enzymes break down pathogens
what do lysozymes do
break down bacteria
what is a neutrophil
made in bone marrow
multi-lobed nuclei
in blood and tissue fluid short-term
what is a macrophage
made in bone marrow
larger than neutrophils
in body organs or lymph nodes
travel in blood as monocytes
what is the inflammatory response
mast cells detect damage and release histamines so blood flow to area increases
histamines cause capillaries to leak so phagocytes and clotting factors are released into wound
phagocytes engulf bacteria and cellular debris
platelets move out of capillary to seal wound
what is phagocytosis
pathogen detected by phagocyte
pseudopodia engulf pathogen
phagosome carries pathogen into cell
lysosomes fuse with phagosome to make phagolysosome
hydrolytic enzymes break pathogen down
debris released via exocytosis
foreign antigens can be presented on cell surface - APC
what are the three main stages of the primary immune response
1- phagocytosis + antigen presentation
2- cell mediated response (T-lymphocytes)
3- humoral immunity (B-lymphocytes)
what happens in the cell mediated response
antigens on antigen presenting cells bind to receptors of T-lymphocytes - CLONAL SELECTION
causes T-cell to divide rapidly by mitosis - CLONAL EXPANSION
can make either T-helper, T-memory or T-killer
what is a T-helper cell
release cytokines
stimulate B cell development + phagocytosis
what is a T-killer cell
kill infected cells using cytotoxins
what is a T-memory cell
immunological memory in secondary response
what happens in humoral immunity
antigens on antigen presenting cells bind to receptors of B-lymphocytes - CLONAL SELECTION
causes B-cell to divide rapidly by mitosis - CLONAL EXPANSION
can make either plasma cells or B-memory
what is a plasma cell
release antibodies
what is B-memory cell
immunological memory
what is the structure of an antibody
flexible hinge region
disulphide bridges
antigen binding site
light and heavy chains
variable region - specific to antigen
constant region - efficient for cloning + protein synthesis, binds to phagocytes
what is an opsonin
antibody attaches to antigens on pathogen surface - helps phagocyte engulf pathogen
what is an anti-toxin
neutralise toxins from pathogens
what is an agglutinin
two binding sites so bind to more than one pathogen at once so cross-links pathogens - ‘agglutinates’ them
what is the secondary response
B+T memory cells go through clonal selection and expansion quickly - more antibodies produced faster - immunological memory
what is an autoimmune disease
when the immune system attacks itself so B+T cells specific to our antigens are destroyed
what is active immunity
immune system activated - B+T mem cells
what is passive immunity
antibodies from mother or injection
what is natural immunity
gained when people acquire a disease normally
what is artificial immunity
deliberate exposure to an antigen
natural active
antigens enter naturally
produce antibodies and specialised lymphocytes
natural passive
mother to foetus
artificial active
vaccines
produce antibodies and specialised lymphocytes
artificial passive
immune serum
body doesn’t produce its own antibodies
what are the forms of antigens in a vaccine
dead pathogen
inactive toxin
antigen isolation
live microorganism
harmless pathogen
what is an epidemic
wide spread communicable disease in 1 country
what is an endemic
area specific disease
what is a pandemic
world-wide spread
what is herd vaccination
vaccinating lots of people to decrease spread in population
what is local vaccination
vaccinating only most at risk people
antibiotic resistance
A random mutation (DNA change) occurs in a single bacteria.
Some mutations protect the bacteria against the antibiotic.
These bacteria survive and divide to produce more bacteria containing the antibiotic-resistance gene.
how to prevent antibiotic resistance
The rotated use of different antibiotics
Taking the full course of antibiotics
Avoiding overuse of antibiotics
