4.1.1 Communicable diseases, disease prevention and the immune system Flashcards
(123 cards)
1
Q
what are communicable diseases
A
- diseases that are caused by infective organisms called pathogens + can be spread between organisms via bodily fluids, bodily contacts + intercourse
2
Q
what are the different types of pathogens
A
- bacteria
- virus
- fungi
- protoctista
3
Q
what are pathogens
A
- microorganisms that attack an organisms + cause disease
4
Q
are bacteria prokaryote / eukaryote
A
- prokaryote
> their cell structure is very different from eukaryotic organisms they infect - no membrane bound organelles
5
Q
what are the diff shapes that bacteria can be
A
rod shaped, spherical, comma, corkscrew
6
Q
how do bacteria cause disease
A
- produce toxins that poison/damage the host cells + causes disease
> does this by breaking down cell membrane
> damage/inactivate enzymes
> interfere with hot cell genetic material
7
Q
what are viruses
A
- non living infectious agents
- basic structure is genetic material (R/DNA) surrounded by protein
8
Q
how do viruses cause disease
A
- invade living cells by genetic material of virus taking over biochemistry of host cell
- virus reproduce rapidly + evolve by developing adaptations to their host
9
Q
what are bacteriophages
A
- viruses that attack bacteria
> viruses are known as the ultimate parasite
10
Q
what are protoctista
A
- group of eukaryotic organisms with a wide variety of feeding methods
> some act as pathogens causing devastating communicable dieases
11
Q
how do protoctista cause disease
A
- they are parasitic so use animals / people as their host
> need vectors to transfer them to the host - can take over cells + break them open
> digest + use cell contents
12
Q
what is fungi
A
- eukaryotic organisms –> often multicellular
13
Q
many fungi are saprophytes meaning that
A
- they feed on dead + decaying matter
14
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some fungi are parasitic meaning that
A
- they feed on living plants + animals
> these are the pathogenic fungi that cause communicable diseases
15
Q
how do fungi cause diseases in plants
A
- they stop plant from photosynthesising + kill it
> when fungi reproduce they produce millions of tiny spores that can spread large distances
16
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how do fungi cause disease (general)
A
- digest living cells + destroy them
17
Q
what are the two modes of actions pathogens produce
A
- damaging host tissues directly
- producing toxins which damage host tissues
18
Q
which pathogens produce toxins that damage host tissues
A
- bacteria produce toxins that damage host cells: break down membrane, inactivate enzymes, interfere with genetic material
- fungi produce toxins that affect host cells + cause disease
19
Q
what type of pathogen is ring rot + host plant + method of transmission + brief symptoms
A
- bacterium
- potato, tomato, aubergines
- infected soil / seeds
- damages leaves, tubers and fruit
20
Q
what type of pathogen is TMV + host plant + method of transmission + brief symptoms
A
- virus
- tobacco
- contaminated tools
- stunts growth, discolours leaves
21
Q
what type of pathogen is late blight + host plant + method of transmission + brief symptoms
A
- protoctista
- potatoes
- wind + rain
- destroys leaves, tubers and fruit
22
Q
what type of pathogen is black sigatoka + host plant + method of transmission + brief symptoms
A
- fungus
- banana
- wind + rain
- attack + destroys leaves
23
Q
what type of pathogen is tuberculosis + method of transmission + brief symptoms
A
- bacterium
- airborne
- damage to lung tissue + suppresses immune system
24
Q
what type of pathogen is HIV/AIDS + method of transmission + brief symptoms
A
- virus
- sexual contact + blood contact
- weakened immune system
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what type of pathogen is influenza + method of transmission + brief symptoms
- virus
- airborne droplets
- fever, weakness, secondary infection
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what type of pathogen is malaria + method of transmission + brief symptoms
- protoctista
- mosquito vector
- fever, chills, nausea
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what type of pathogen is athletes foot + method of transmission + brief symptoms
- fungus
- contact with an infected surface
- cracked itchy skin
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what is direct transmission
- pathogens transferred directly from one individual to another
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what are some examples of direct transmission in animals
- direct contact:
> bodily fluids, kin to skin
- inoculation: through a break in the skin
> animal bite, puncture wound
- ingestion: taking in contaminated food
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what is indirect transmission
- pathogen travels from one individual to another indirectly
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what are some examples of indirect transmission in animals
- fomites:
> inanimate objects like bedding
- droplet infection (inhalation):
> saliva, mucus, sneeze, cough
- vectors: transmits communicable pathogens from one host to another
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what does a vector do
- transmits communicable pathogens from one host to another
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what are some of the factors that effect the transmission of communicable diseases in animals
- overcrowded living + working conditions
- poor nutrition
- climate change (introduce new vectors + diseases)
- culture + infrastructure
- socioeconomic factors: e.g. lack of trained health workers
- poor disposal of waste
- compromised/weakened immune system
34
describe an example of direct transmission in plants
- direct contact of healthy plant with any part of a diseased plant
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what are some examples of indirect transmission in plants
- soil contamination
> infected plants leave pathogens in soil that can infect next crop
- vectors
> wind
> water
> animals
> humans
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what are some of the factors that affect the transmission of communicable diseases in plants
- planting variety of crops susceptible to disease
- overcrowding inc likelihood of contact
- poor mineral nutrition
- damp warm conditions
- climate change
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what are some passive physical defenses in plants to protect from pathogens
- waxy cuticle
- casparian strip in root endodermis
- bark
- cellulose cell walls
- sticky resins in bark
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what are some passive chemical defenses in plants to protect from pathogens
- secreting toxic compounds
- secreting enzyme inhibitors (inhibit enzymes needed by pathogens to enter plant)
- stomatal closure
- secreting compounds which support growth of competitors of pathogen
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what is hypersensitivity / necrosis in plants
- an active defence
- immediate death of tissues surrounding infection site to prevent spread of infection (cell suicide)
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what is callose deposition in plants
- an active defence
- callose is large polysaccharide that blocks sieve tubes (phloem or plasmodesmata, preventing spread of pathogen
> also deposited in cell walls
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what is tyloses in plants
- an active defence
- growths (made of chemicals called terpenes) that block xylem
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what is cell signaling in plants
- active defence
- leads to increased production of defence chemicals
> e.g. antibiotics, antifungals, toxins e.g. cyanide
43
name some non-specific defenses in animals
- skin
- mucous membranes
- lysosomes in tears + urine
- expulsive refluxes
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how does skin act as a non-specific defence
- covers body + prevents entry of pathogens
- produces sebum that inhibits growth of pathogens
> lactic acid + fatty acid produced from sweat/sebaceous glands are acidic
- generally impermeable to most pathogens
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how do mucous membranes act as non-specific defences
- these line parts of body most likely to come into contact with pathogens
> airways, digestive / genital tract
- mucous secreted traps pathogens + contains lysosomes that destroy bacterial + fungal cell walls
> also contain phagocytes
46
how do expulsive refluxes act as non-specific defences
- coughing + sneezing
- areas prone to infection are sensitive to dust / microorganisms
> these are reflexes that happen automatically to expel foreign bodies
47
what is thromboplastin
- enzyme that triggers a cascade of reactions resulting in formation of blood clot
48
what does serotonin do
- makes smooth muscles in walls of blood vessels contract so they narrow + reduce supply of blood to the area
49
give an overview of wound repair
- clotting factors activate enzyme cascade
- mesh forms + traps platelets + forms clot
- clot dries out forming scab
- epidermal cells below scab grow + collagen deposited
- once new skin formed, scan falls off
50
describe the steps in wound repair
- damage to blood vessel wall exposes collagen + releases clotting factors
- platelets come into contact with collagen + release mor clotting factors
- platelets form temporary plug
- inactive thrombokinase activated by clotting factors
- active thrombokinase works with calcium to activate prothrombin
- thrombin catalyses conversion of soluble fibrinogen in plasma to insoluble
- fibrin covers temporary platelet plug forming mesh which traps red blood cells
- new cells grow under clot
- enzyme plasmin releases to dissolve clot
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what do mast cells release
- when activated in damaged tissue they release chemicals called histamines or cytokines
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what do histamines do
- increase permeability of capillaries so blood plasma (fluid) leaks out into surrounding tissue
- also dilate blood vessels causing localised heat + redness (prevents pathogens reproducing)
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what do cytokines do
- attract white blood cells (phagocytes) to the site
> they dispose of pathogens by phagocytosis
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what are phagocytes
- specialised white cells that engulf + destroy pathogens
> produced throughput life by bone marrow
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what are the 2 main types of phagocytes
- neutrophil
- macrophages
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what are some features of neutrophils
- lobed nucleus
- short lived - die after digesting bacteria
- travel in blood + tissue (enter tissue fluid during infections)
- large numbers during infections
- make up much of pus (dead)
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what are some features of macrophages
- larger than neutrophils
- found in lymph / organs (not blood)
- made in bone marrow as monocytes (called macrophages once reached organs)
- long lived
- display antigens from the pathogens to initiate specific immune response
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what are some features of dendritic cells
- have long processes that inc SA to interact with pathogens
- found in areas near surface, skin, digestive tract
- migrate to lymph nodes after phagocytosis
- are antigen presenting cells (APC's)
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describe the steps of phagocytosis
- pathogens produce chemicals that attract phagocytes
- ingestion of microbe by phagocyte
- formation of phagosome (pathogen enclosed in vacuole)
- phagosome combines with lysosome to form phagolysosome
- enzyme from lysosome digests + destroys pathogens
- residual body containing indigestible material expelled
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what do APC's do
- they don't fully digest all the pathogen
> the antigen combines with special protein complex + placed on APC's own membrane
- the APC carries itself to lymph system where lymphocytes produce specific antibodies in response to antigens that are foreign to body
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how are cytokines helpful in phagocytosis
- act as cell-signaling molecules informing other phagocytes that body is under attack + stimulates them to move to site of infection / inflammation
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how are opsonins helpful in phagocytosis
- they're chemicals that bind to pathogens + 'tag' them so they are more easily recognisable by phagocytes
> phagocytes have receptors that bind to common opsonins
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what is the specific immune response
- refers to production of specific antibodies by lymphocytes to combat infection by specific pathogens
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what are white blood cells
- cells in blood that protect against infection
> specific immune system based on white blood cells called lymphocytes
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what are phagocytes
- white blood cells responsible for non specific immune response
> they engulf + destroy pathogens and present antigens to trigger the specific immune response
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what are lymphocytes
- white blood cells responsible for the specific immune response
> they produce antibodies which help prevent pathogens causing disease through agglutination, labeling, attaching to flagella, antitoxin action and neutralisation
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what are B + T cells
- both types of lymphocytes
> B mature in Bone marrow + T mature in Thymus gland
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what are the 3 types of B lymphocytes
- B plasma cells
- B effector cells
- B memory cells
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what do B plasma cells do
- produce specific antibodies to particular antigens + release them into circulation
- active plasma cells live only for few days but produce many when allice
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what do B effector cells do
- divide to form plasma cell clones
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what do B memory cells do
- live for very long
- provide immunological memory
> programmed to remember specific antigen + enable body to make very rapid response when pathogen with that specific antigen is encountered again
> then is produces B plasma cells
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what are antibodies also known as
- immunoglobulins
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what are antibodies
- produced by lymphocytes in response to infection
- they are globular glycoproteins that attach to antigens + make them harmless
74
describe the structure of an antibody
- made of 2 long polypeptide chains called heavy chains + 2 shorter ones called light chains
> chains held together by disulfide bridges + also within polypeptide chains holding them in shape
- each antibody has 2 identical antigen binding sites - variable regions
> order of amino acids in variable region determines shape of binding site
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how do antibodies cause agglutination
- they clump together bacteria makin it easier for pathogens to destroy + making them less likely to spread
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how do antibodies carry out neutralisation
- they block binding sites on pathogens so unable to bind to host cell
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how do antibodies work as antitoxins
- they block toxins
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how does antibodies attaching to bacteria flagella aid in phagocytosis
- makes bacteria less active + easier for phagocytes to engulf
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how do antibodies act as opsonins
- they attach to antigens forming antigen-antibody complex
> this acts as an opsonin so complex is easily identified + engulfed/destroyed by phagocytes (produces a signal)
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what are the 4 main types of T lymphocytes
- T helper cells
- T killer cells
- T memory cells
- T regulator cells
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what do T helper cells do
- bind to surface antigens on APC's because of CD4 receptors on their cell-surface membrane
- produce interleukins (type of cytokine) that stimulate:
> activity of B cells which increase antibody production
> production of other T cells
> attract + stimulate macrophages to ingest pathogens with antigen-antibody complexes
82
what do T killer cells do
- produce chemical perforin which kills pathogens by making holes in cell membrane so its freely permeable
> these are are specific to particular antigens
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what do T memory cells do
- live long + part of immunological memory
- if they encounter antigen again they divide rapidly to form huge number of clones of T killer cells that destroy pathogen
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what do T regulator cells do
- suppress immune system, acting to control + regulate it
- stop immune system once pathogen is destroyed
> makes sure body recognises self antigens + doesn't set up autoimmune response
> interleukins important in this control
85
what are the 2 types of immunity
- cell mediated immunity
- humoral immunity
86
what happens in cell mediated immunity
- T lymphocytes respond to cells that have been altered e.g. by infection, mutation + cells from transplanted tissue
- in non specific defence system, macrophages engulf/digest pathogens (phagocytosis) + process antigens forming APCs
- receptors on some T helper cells fit antigens + they become activated + produce interleukins stimulating T cells to divide ---> form clones T helper cells
- clones of T cells can develop into T memory, produce interleukins that stimulate phagocytosis / B cells division + clones of T killer cells
87
what happens in humoral immunity
- B lymphocytes have antibodies on cell surface membrane that binds to complimentary antigen on pathogen
> B cell engulf + process antigen to become APCs
- activated T helper cell bind to B cell APC (clonal selection)
- interleukins produced by T helper activate B cell
- activated B cell divide mitosis + clones of plasma / B memory cells (clonal expansion)
- cloned plasma cell produce antibodies that bind to antigen + disable them or act as opsonins / agglutinins
- clones B cell can develop into B memory cell
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what types of cells does cell mediated immunity target
- our own cells that have been altered in some way by virus, infection, antigen processing or mutation (cancer)
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what types of cells does humoral immunity target
- foreign antigens found in pathogens not in our cells
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what is an autoimmune disease
- when the immune system starts to attack healthy body tissue as it stops to recognise self antigens
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what is natural immunity
- types of immunity that occur naturally in the body
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what is natural active immunity
- when you encounter a pathogen for the first time the immune system is activated + antibodies form + antigen destroyed
- immune system produces T + B memory cells so it can recognise antigen in future
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what is natural passive immunity
- short term immunity when mother's antibodies passed to foetus via placenta + remains for several months
- colostrum contains lots of antibodies that remain on surface of baby's gut wall + pass into blood
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what is artificial immunity
- immunity without requiring contact with live pathogens
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what is artificial passive immunity
- used when very rapid immune response is needed
- human antibodies injected into bloodstream of another
> gives temporary immunity
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what is artificial active immunity
- the immune system of body is stimulated to make its own antibodies to a safe forms of an antigen
> vaccine injected into bloodstream
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what is an epidemic
- when a communicable disease spreads rapidly to a lot of people at a local or national level
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what is a pandemic
- when the same disease spreads rapidly across a number of countries + continents
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what are vaccines used for
- to give long term immunity to many diseases + prevent epidemics
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describe the steps to how a vaccine works
- pathogens made safe in a number of ways so antigens are intact but there is no risk of infection
> may be a killed or weakened strain
- small amounts of safe antigen injected into blood
- primary immune response triggered by foreign antigens + body produces antibodies + memory cell
- if you come into contact with live pathogen the secondary immune response triggered + you destroy pathogen
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what is herd immunity
- when a significant (large) number of people in population have been vaccinated so gives protection to those who haven't
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what is an example of an autoimmune disease + how does it work
- arthritis
- immune system attacks smooth cartilage of joints + leads to inflammation that can affect entire body
> most commonly affects hands, spine, knees + hips
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what is ring immunity
- when you vaccinate all the people around an outbreak of a disease to contain it
> can be contained with quarantine
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what are some common types of medicine
- antibiotics
- antifungals
- antivirals
- painkillers
- ointment
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what are some natural sources of medicine + examples
- plants + microorganisms
> penicillin (mould), aspirin (willow bark)
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what does it mean if a drug / medicine is sourced syntheitically
- it is made artificially in the lab + use computer aided design to help model the shape of the medicine to target specific areas of the pathogen
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what does it mean if a medicine is sourced semi-synthetically
- when a natural source is modified (synthetically)
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why is it important to maintain biodiversity in terms of medicine
- make sure we don't destroy a plant, animal or microorganism which could give us the key to a life-saving drug
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what is personalised medicine
- a combination of drugs that work with your individual combination of genetics + disease
> you give people different medicine based on their genetics + which will be most effective
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how is personalised medicine achieved
- by analysing the human genome rapidly which gives an understanding of the genetic bases of many diseases
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what is nanotechnology
- where tiny, non-natural particles are used for biological purposes
> e.g. delivering drugs to a very specific site within the cells of pathogens
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what are antibiotics used for
- treating bacterial diseases (not viruses)
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what is selective toxicity
- when antibiotics interfere with the metabolism of the bacteria without affecting the metabolism of human cells
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what are some mechanisms of action in antibiotics
- cell wall synthesis
- cell membrane permeability
- metabolic reactions
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what is bacteriostatic antibiotic
- doesn't kill bacteria but prevents their growth (relies on immune system to kill them)
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what is bactericidal antibiotic
- kills bacteria + doesn't rely on immune system to kill them
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what does a broad spectrum antibiotic do
- affect a large number of diff bacteria (even those that are beneficial to you)
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what does a narrow spectrum bacteria do
- affects a small number of different bacteria
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what leads to antibiotic resistance
- random mutation to an individual bacteria which is unaffected by the antibiotic
- due to natural selection + rapid rate of reproduction in bacteria, this quickly leads to a large population of resistant bacteria
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what are some factors that can leads to increased antibiotic resistantce
- antibiotics added to animal feed to prevent disease
- oversubscription of antibiotics
> MRSA
- not completing your antibiotic course
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what are some things you can do to fight antibiotic resistance
- reduce unnecessary use of antibiotics
- ensure course of antibiotics goes to completion
- focus on hygiene + cleaning sheets / surfaces
> kill pathogens without requiring antibiotics
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