4.1 communicable diseases Flashcards
What are 3 diseases caused by bacteria
Tuberculosis
bacterial meningitis
ring rot
What are 3 diseases caused by viruses
HIV/AIDS
influenza
tobacco mosaic virus
What are 2 diseases caused by protoctista
Malaria
Potato/tomato blight
What are 3 diseases caused by fungi
black sigatoka
ring worm
athletes foot
Why are some bacteria harmful
They reproduce rapidly and their presence can cause disease by damaging cells or by releasing waste products which are toxic to us
How do viruses cause disease
They have a core of genetic material, outer envelope of lipoproteins and inner protein coat.
without organelles to respire or absorb nutrients the virus can’t grow so it infects host cell to replicate and damages it
How do protoctista cause disease
They cause harm by entering the cell and feeding on its content as it grows
How do fungi create harm
In animals fungi lives in the skin and hyphae grow to the skin surface
In plants it lives in the vascular tissue and hyphae release extracellular enzymes to digest tissue
what are the symptoms of tuberculosis
Affects many parts of the body killing tissues and cells and the lungs are mostly affected
cough
What are the symptoms of bacterial meningitis
infection of the meninges; brain and spinal cord membranes become swollen and may cause damage to the brain or nerves
headache, rash
What are the symptoms of ring rot
Ring of decay in the vascular tissue of a potato tuber or tomato
accompanied with leaf wilting
What are the symptoms of HIV/AIDS
Attacks cells in immune systems and compromises immune response
What are the symptoms of influenza
Attacks respiratory system and can cause muscle pain and headaches
What are the symptoms of tobacco mosaic virus
mottling and discolouration of leaves
What re the symptoms of malaria
parasite in the blood that causes headache, fever and chills and may progress to coma or death
What are the symptoms of blight
Affects both leaves and potato tubers
watery rot of leaves which soon collapse and turn brown
What re the symptoms of black sigatoka
leaf spots in banana plants
What are the symptoms of ringworm
Circular rash caused by growth of fungus
What are the symptoms of athletes foot
growth under skin of feet particularly toes
define passive defenses
they are present before infection and prevent entry and spread of pathogens
what are the 7 physical plant defenses
cellulose cell wall
lignin thickening of cell walls
waxy cuticle
bark
stomata closure
callose
tylose
describe how to cell wall is a physical plant defense
acts as a physical barrier and contains a variety of chemicals which may activate when a pathogen is discovered
describe how lignin is a physical plant defense
the lignin thickening of cell walls are waterproof and undigestible
describe how waxy cuticles are a physical plant defense
prevents water from collecting and the absence of water protects the plant by ensuring the pathogen doesn’t survive
describe how bark acts as a physical defense for plants
it acts as a barrier and contains chemical defenses against pathogens
describe how stomatal closure acts as a physical defense in plants
guard cells close to prevent entry of pathogen
describe how callose acts as a physical defense in plants
it is a polysaccharide deposited in phloem sieve tubes blocking the flow in it and preventing spread of pathogens
describe how tylose acts as a physical defense against pathogens
it is a projection that fills the xylem vessel so that it can no longer carry water and spread pathogens
it also contains chemical toxic to pathogens e.g. terpenes
describe chemical defenses
terpenoids, phenols, alkaloids and hydrolytic enzymes that may be present before infection.
However, they require a lot of energy to be produced so they usually aren’t until a pathogen is detected
what occurs during active defense in plants
already existing defenses are fortified
thickened cell wall
increased production of chemicals
deposition of callose
oxidative bursts that can damage invading cells
name the 5 chemicals produced during plan defense action
terpenoids
phenols
alkaloids
defensins
hydrolytic enzymes
what is the action of terpenoids
they are essential oils with anti bacterial and anti fungal properties e.g. menthols in mint
what is the action of phenols
they are anti biotic and anti fungal
tannin inhibits insect attacks by binding to their salivary proteins and digestive enzymes deactivating them and can inhibit insect growth and may even cause death
what is the action of alkaloids
nitrogen containing compounds e.g. caffeine and cocaine that have a bitter taste to inhibit herbivores
they also act on metabolic reactions via inhibiting or activating enzymes e.g. some may inhibit protein synthesis
what is the action of defensins
they are small cysteine rich proteins with broad anti-microbial activity and appear to act in plasma membranes possibly inhibiting ion channels
what is the action of hydrolytic enzymes
found in spaces between cells and include:
chitinases - break down chitin in cell wall
glucanases - break down glycosidic bonds in glucans
lysosomes - can degrade bacterial cell wall
define direct transmission
passing a pathogen from host to new host with no intermediary
define indirect transmission
passing a pathogen from host to new host via a vector
what are the 4 direct transmissions of disease
physical contact
faecal
droplet infection
spores which can be carried in soil or air
describe physical contact transmission and what factors affect it
physical contact e.g. HIV athletes foot and bacterial meningitis
- hygiene and sanitisation of surfaces
describe faecal/oral transmission and what factors affect it`
faecal - oral transmission e.g. cholera and food poisoning usually by eating or drinking food infected with pathogen
- using human waste to fertilise crops
-cross-contamination of food
-washing food
describe droplet infection and what factors affect it
droplet infection e.g. tuberculosis and influenza
-cover mouth when sneezing or coughing
- masks
Describe infection by spores and what factors can affect transmission
spores which can be carried in soil or air e.g. anthrax
- washing skin after soil contact
-masks
what other factors can affect transmission of a disease
overcrowding
poor ventilation
poor diet
homelessness
not being exposed to that disease before and not having resistance
what are some indirect methods of transmission
vectors
for example the the plasmodium parasite that causes malaria uses the anophales mosquito as a vector
what are some example of direct transmission of disease in plants
soil contamination
protist or fungi in soil
e.g. TMV, tomato blight, black sigatoka
What are some examples of indirect transmission of pathogens in plants
vectors such as wind, water, animals and humans
define inflammation
swelling and redness of tissue caused by infection
what are the 5 primary non-specific defenses against pathogens
skin
blood clotting
mucous membranes
coughing or sneezing
inflammation
How does the skin act as a primary non-specific defense against pathogens
the outer layer of the skin (epidermis) consists of layers of cells most of which are keratinocytes and the keratinised layer of cells acts as a barrier to pathogens
How does blood clotting act as a primary non-specific defense against pathogens
It involves calcium ions and at least 12 other clotting factors in an enzyme cascade.
once the clot has formed it begins to dry out and form a scab creating a temporary seal under which the skin is repaired
Describe how the skin is repaired after a scab has formed
firstly there is a deposition of fibrous collagen under the scab and stem cells in the epidermis divide by mitosis to form new cells which migrate to the edges of the cut and differentiate to form new skin.
New blood vessels grow to supply oxygen and nutrients to the new tissues.
The tissues contract to help draw the edges together so that the repair can be completed
describe the enzyme cascade
damage to the blood vessel wall exposes collagen and releases clotting factors
platelets bind to collagen and release clotting factors such as inactive thrombokinase in blood which is a factor and active thrombokinase (enzyme) and calcium ions
soluble fibrinogen in blood becomes insoluble fibrin which attaches to platelets in plug and clots
How do mucous membranes act as primary non-specific defenses against pathogens
they trap pathogens that may be in the body and are wafted where it can be swallowed (if in the airways )
How does coughing and sneezing act as a primary non-specific defense against pathogens
the sudden expulsion of air will carry the microorganism causing the irritation
how does inflammation act as a primary non-specific defense against pathogens
mast cells detect the presence of micro organisms and release histamines which are cell-signaling substances.
this causes vasodilation and make the capillary walls more permeable to white blood cells and some proteins
blood plasma and phagocytic cells leave the blood and enter the tissue fluid and leads to increased production of tissue fluid which causes swelling (oedema)
Excess tissue fluid is drained into the lymphatic system where lymphocytes are stored and can lead to pathogens coming into contact with them and initiating an immune response
what are other examples of primary defenses?
Eyes are protected by antibodies and enzymes in the tear fluid
The ear canal is lined by ear wax which traps pathogens
The female reproductive system is protected by a mucus pug in the cervix and relatively acidic conditions in the vagina
Describe an antigen presenting cell
It is a cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system
define antigen
a protein on the pathogens outer membrane which is recognised as non-self (foreign) and can initiate an immune response
describe opsonins
protein molecules that attach to the antigen on the pathogens surface and are a type of antibody
What is the need for opsonins being non-specific
This enables them to attach to a variety of pathogen antigens
What is the role of opsonins
they enhance the ability of phagocytic cells to bind and engulf the pathogens
Describe phagocytic
they are the first line of secondary defence and are specialised cells in the blood and tissue fluid which engulf and digest pathogens
Which phagocytes are the most common
neutrophils
Describe neutrophils and their role
They are multi-lobed white blood cells which are produced in the bone marrow which travel in the blood and squeeze out of it into the tissue fluid.
Neutrophils contain a large number of lysosomes and they engulf and digest pathogens and will die soon after. They then may collect after an infection as pus
Describe the difference between macrophages and monocytes
macrophages travel in the blood as monocytes and usually reside in the lymph nodes where they will mature into macrophages
What are dendritic cells and where are they found
They are a type of macrophage and are found in peripheral tissues
Describe macrophages and their role
They are a type of white blood cell which is produce in the bone marrow and play an important role in initiating the specific immune response against a pathogen
When a macrophage engulfs a pathogen it doesn’t fully digest it but rather saves the pathogen and and is moved to a special protein complex on the surface of the cell and becomes and antigen-presenting cell
What does the special protein complex on the antigen-presenting cell ensure
That it isn’t mistaken for a foreign cell and engulfed by other phagocytes.
How do the antigen presenting cells help with the initiation of the specific immune response
It increases the chance that the antigen will come into contact with the Band T lymphocytes
Describe cytokines
hormone-like molecules used in cell signalling to activate an immune response
Describe the specific immune response
It involves B and T lymphocytes and produces antibodies which neutralises the foreign antigen
It can also provide long-term protection by producing immunological memory through the release of memory cells.
What are the 6 types of lymphocytes involved in the specific immune response
Plasma cells
B memory cells
T helper cells
T memory cells
T killer cells
T regulator cells
define antibodies
a protein which is complementary and attaches to the antigen of a pathogen and neutralises it
define interleukins
signalling molecules which are used to communicate between white blood cells
What is the role of T helper cells
they release cytokines that stimulate Bcells to develop and stimulate phagocytosis
What is the role of T killer cells (cytotoxic )
Attack and kill host-body cells which display the foreign antigen
What is the role of T memory cells
Provide immunological memory
What is the role of T regulator cells
They shut down the immune response after the pathogen has been successfully removed and are involved in preventing autoimmune diseases
What is the role of plasma cells
They circulate in the blood manufacturing and releasing antibodies
What is the role of B memory cells
Provide immunological memory
describe three examples of using cytokines in cell communication
macrophages release monokines , some attract neutrophils and others stimulate B cells to differentiate
T cells and macrophages release interleukins which can stimulate clonal expansion and differentiation of B and T cells
Many cells can release interferon which inhibits virus replication and stimulates T killer cell activity
When does an autoimmune disease arise
when antibodies start to attack our own antigens
define clonal selection
selection of a specific B or T cell that is specific to the antigen
define clonal expansion (proliferartion)
once the correct lymphocyte has been activated it must replicate to become more efficient which is done by mitotic division
Why are antibodies described as immunoglobulins
they are complex globular proteins produced by plasma cells
describe the structure of antibodies
they are Y shaped with disulphide bridges and hinge regions to allow flexibility
What are the three main groups of antibodies
opsonins
agglutinins
anti-toxins
Describe how opsonins work as antibodies
they bind to the antigen on the pathogen and then act as binding sites for phagocytic cells
Describe how agglutinins work
The antibody molecule crosslinks pathogens by binding to more than one at a time and clumps pathogens together physically impeding them from carrying out their functions
Describe how anti-toxins work
some antibodies bind to molecules that are released by phagocytic cells rendering them harmless
describe how the secondary immune response differs from the first
The concentration of antibodies rises quicker and sooner and is usually quick enough to prevent the host from experiencing any symptoms
Define vaccine
a way of stimulating an immune response so that immunity is acheived
what are the 5 types of vaccine
whole live microorganisms are injected which aren’t as harmful as the real pathogen but have similar antigens cowpox and smallpox
weakened version of pathogen - measles and TB
dead pathogen - cholera
a preparation of the antigen from a pathogen - hep B
A toxoid (harmless version of toxin ) - tetanus
Define herd vaccination
Using a vaccine to provide immunity to all or almost all of those at risk. Once enough people are immune the disease can no longer be spread through the population
Define ring vaccination
used when a new case of a disease is reported and all the people in the immediate viccinity of the area are vaccinated
Define active immunity
Where the immune system is activated and the body produces antibodies e.g infection
Define artificial immunity
Immunity achieved through medical intervention e.g. vaccines
Define natural immunity
immunity achieved through natural life processes
define passive immunity
immunity achieved when antibodies are passed to the individual e.g. breast feeding and injection
define antibiotic
chemical which prevents the growth of micro organisms and can be antibacterial or antifungal
Define personalised medicine
development of designer medicine for individuals
Define synthetic biology
the re-engineering of biology this could be through production of new molecules that mimic natural processes or the use of natural molecules to produce new biological systems which don’t exist in nature
