communicable diseases Flashcards
bacterial infections
- tuberculosis
- lungs, bacteria kills cells/tissues + suppresses the immune system - bacterial meningitis
- infection and swelling of membranes around the brain and spinal cord - ring rot
- damage/decay of potato tubers + tomatoes
fungal infections
- athlete’s foot
- skin of foot/ between toes - ringworm
- skin of cattle, infectious grey rash - black sigatoka
- destroys plant leaves
viruses
- HIV/ aids
- attacks the immune system - Influenza
- attacks the respiratory system - TMV
- pattern of leaf discolouration
protoctista
- malaria
- plasmodium parasite - fever leads to coma/death
- hard to make vaccine because the Protoctista hide in red blood cells so are hard to detect, and they have 3 stages to their life which makes it more challenging - potato/tomato blight
- hyphae penetrate into host cells in leaves/fruits
animal direct pathogen transmission
- physical contact
- droplets
- contaminated surfaces
- eating or drinking
- spores
animal indirect pathogen transmission
- vectors
plant-pathogen transmission
- soil contamination
- contact
- root entry
- airborne transmission (spores carried through air)
- insects/ vectors
factors which affect transmission
- overcrowding
- poor nutrition
- climate change - new diseases + vectors
- increased rainfall
- socioeconomic factors
- poor soil richness
- warm damp conditions
plant defences
PHYSICAL
- waterproof lignin walls
- waxy cuticles
- guard cells
- callose deposits in sieve tubes - blocks spreading
- tylose - swelling which fills xylem - blocks spreading
ACTIVE
- production of repellant chemicals
- terpenoids - strong-scented, antibacterial properties
- alkaloids - bitter taste, prevent eating - hydrolytic enzymes - break down pathogen cell walls
PNSDAP
skin
- prevents entry of the pathogen
- skin flora of healthy microorganisms outcompete pathogens
- dead cells act as effective barriers
PNSDAP
blood clotting
- site of damage
- platelets adhere to the site of damage
- clotting factors released as enzyme cascade is activated
PNSDAP
wound repair
- scab forms
- new skin forms underneath (cell differentiation)
PNSDAP
mucous membranes
- specialised epithelial tissue covered in mucous
- goblet cells secrete mucous which traps pathogen
- mucous contains hydrolytic enzymes which destroy bacterial and fungal cell walls
- cilia beat mucous into acidic stomach
PNSDAP
expulsive reflexes
- coughing, sneezing
- ejects pathogens
PNSDAP
inflammation
- swelling of infected tissue
- histamine released by cells causing vasodilation
- capillary walls more permeable to white blood cells
SNSDAP
phagocytes
- engulf, digest and kill pathogens
- considered secondary because they only act after the pathogen has entered the body
neutrophils = most common phagocyte
- recognises antigen on pathogen as foreign
- engulfs pathogen
- pathogen enclosed in vacuole - phagosome
- phagosome combines with lysosome - phagolysosome
- enzymes in lysosome break down and digest the pathogen
- produces fragments which are combined with glycoproteins = MHC - major histocompatibility complex
- MHC moves antigens onto its own surface producing antigen-presenting cells - APC’s
antigen presentation
- so T and B lymphocytes can recognise and come into contact with the APC’s
- full specific immune response stimulated
cytokines
- cell signalling, molecules that have a specific shape complementary to the shape of the receptor site of lymphocytes, they bind to their receptors
- stimulate phagocytes to move to the site of infection (specific immune response)
opsonins
- tag to/mark invasive pathogen so that they can be recognised
- stimulates phagocytosis
macrophage
type of phagocyte, responsible for detecting, engulfing and destroying pathogens
produced through differentiation of monocytes
specific immune response
4 main steps
- APC antigens bind to T helper cell receptors, activating the T helper cells.
- clonal selection occurs of T helper and killer cells
- for each type of cell, clonal expansion occurs = mass cell replication - T helper cells produce interleukins (cell signalling molecules) which activates B cells
- clonal expansion of B cells
- some B cells = B plasma cells which manufacture antibodies/ immunoglobins
- some B cells = B memory cells which provide immunological memory - T killer cells attach to infected cells and secrete toxic substances into the cells, killing them
- T regulator cells suppress and control the immune system by stopping immune responses post pathogen elimination and making sure body recognises self-antigens
interleukins
cell signalling molecules
autoimmune disease
the immune system doesn’t recognise its own antigens and attacks different parts of the body
e.g. Lupus, Arthritis
anti-toxins
antitoxins bind to harmful substances/toxins released by pathogens and render them harmless
agglutins
cross-linking between pathogens causes them to group together which means pathogens are more readily engulfed
antibody regions
top of each branch of Y = antigen-binding site
variable region = specific to antigen
S-S disulfide bridges hold polypeptide together
hinges between heavy and light polypeptide chains allow bending - bind to more than 1 antigen
constant region - attachment to phagocytes
natural active immunity
- natural response
- production of antibodies
- body brings about the response
natural passive immunity
- foetus receives antibodies across the placenta
- foetus doesn’t produce antibodies itself
artificial active immunity
- vaccination
- antibodies produced by the body when foreign substance is introduced into the body
artificial passive immunity
- antibodies from another organism are injected into the bloodstream of another
- short-lasting
vaccinations
provide immunity to specific diseases by exposure to harmless antigenic material
- dead or inactivated bacteria
- weakened strains
- modified toxin molecules
- genetically engineered antigens
vaccination types (mass, herd, ring)
mass
- prevent spread in the wider population
herd
- provides immunity to most/all of the population
ring
- people in the vicinity are vaccinated to prevent spreading
parasite
- lives in the host
- feeds on the host
- harms the host
bacteria and antibiotics
- some develop resistance
- bacteria can’t be immune because they don’t have an immune system
- they are unicellular only multicellular organisms can have an immune response
T cells
matured in thymus
4 types T killer T helper T regulator T memory
