Disease And The Immune .System :) Flashcards
What organisms can get diseases?
Both plants and animals
What is a pathogen?
An organism that causes disease
What types of pathogens are there?
Bacteria
Viruses
Fungi
Protoctista
What is protoctista?
A type of single-celled eukaryotic organism
What are communicable diseases?
Diseases that spread between organisms
What diseases do you need to know about?
Tuberculosis, bacterial meningitis, ring rot, HIV/AID’s/ influenza/ tobacco mosaic virus, black Sigatoka, ringworm, athlete’s foot, potato/ tomato late blight/ malaria
What is mostly affected by tuberculosis?
Animals, typically humans and cattle
What causes tuberculosis?
Bacterium
What is mostly affected by bacterial meningitis?
Humans
What causes bacterial meningitis?
Bacterium
Who is mostly affected by ring rot?
Potatoes, tomatoes
What causes ring rot?
Bacterium
What causes HIV/AID’s?
Virus
Who is mostly affected by HIV/AID’s?
Humans
Who is mostly affected by influzena?
Animals, including humans
What causes influenza?
Virus
What causes tobacco mosaic virus?
Virus
Who is mostly affected by tobacco mosaic virus?
Plants
Who is mostly affected by black sigatoka?
Banana plants
What causes black Sigatoka?
Fungus
What causes athlete’s foot?
Fungus
Who is mostly affected by athlete’s foot?
Humans
Who is mostly affected by potato/ tomato late blight?
Potatoes/ tomatoes
What causes potato/ tomato late blight?
Protoctist
Who is mostly affected by malaria?
Animals, including humans
What causes malaria?
Protoctist
What is a disease?
A condition that impairs normal functioning of an organism
What is direct transmission?
When a disease is transmitted directly from one organism to another
How can direct transmission happen?
Droplet infection (coughing or sneezing tiny droplets of mucus or saliva directly into someone. Sexual intercourse Touching an infected organism
How is HIV transmitted?
Directly between humans via sexual intercourse
How can athlete’s foot be spread?
Via touching
What is indirect transmission?
When a disease is transmitted from one organism to another via an intermediate
Name some indirect transmission forms?
Air
Water
Food
Another organism (vector)
How is potato/tomato late blight spread?
When spores are carried between plants- first in the air, then in water
How is malaria spread?
Between humans and other animals via mosquitoes insects (vector) that feed on blood
Do mosquitoes cause malaria?
No just spread the protoctista that cause it
What three things affect disease transmission?
Living conditions
Climate
Social factors
What type of living conditions increases transmission of many communicable diseases?
Overcrowded living conditions
Give an example of when overcrowded living conditions increase transmission of a communicable disease? Is
TB spread directly via droplet infection and indirectly because bacteria can remain in air for long periods of time and infect new people.
What happens to risk of TB infection in overcrowded areas?
It increases
Give a plant example of when climate affects infection of disease?
Potato/ tomato late blight is especially common during wet summers because spores need water to spread.
Give a animal example of when climate affects infection of disease?
Malaria is most common in tropical countries which are humid and hot because ideal conditions for mosquitoes (vector) to breed
In humans what also can increase transmission of communicable diseases?
Social factors
Give an example of when social factors can increase transmission of communicable diseases?
The risk of catching HIV is high in places with limited access to: good health care, good health education
How can limited access to good healthcare increase risk of HIV?
People are less likely to be diagnosed and treated for HIV and the mort effective anti-HIV drugs are less available do virus more likely to be passed on to others
How can limited access to good health education increase risk of HIV?
You can’t inform people about how HIV is transmitted and how it can be avoided such as safe-sex like using condoms
What are the two types of defences plants have?
Physical and chemical
Name three physical defences of plants?
Waxy cuticle
Cell wall
Callose
How is a waxy cuticle a physical defence for a plant?
Provides physical barrier against pathogen entry
May also stop water collecting on leaf reducing risk of infection by pathogen transferred between plant and water.
Most plant leaves and stems have them
How is a cell wall a physical plant defence?
Plant cells are surrounded by cell walls forming physical barrier against pathogens that make it past the waxy cuticle
What is callose?
A polysaccharide produced by plants.
What happens to callose during times of stress?
Gets deposited between plant cell walls and plasma membrane
What’s a time of stress?
Pathogen invasion
How does callose help as a physical defence?
Callose desposition may make it harder for pathogens to enter cells. Callose deposition at plasmodesmata may limit spread of viruses between cells.
What else other than physical defences do they rely on?
Chemical defences
Produce antimicrobials chemicals which kill pathogens or inhibit growth.
Name two chemicals plants produce as chemical defence?
Saponins
Phytialexins
What do saponins do?
May destroy cell membranes of fungi and other pathogens
What do phytoalexins do?
Inhibit growth of fungi and other pathogens
What are other chemicals by plants for insects?
Toxic reducing amount of insect-feeding on plants reducing risk of infection by plant viruses carried by insect vectors
What do pathogens need to do to cause disease?
Enter an organism
What does pathogens needing to enter an organism to cause disease mean most animals including have?
A range of primary, non-specific defences to help prevent this from happening
Name 6 primary non-specific defences in animals?
Skin, mucous membranes, blood clotting, inflammation, wound repair and expulsions reflexes
How is skin a primary non-specific defence?
Acts as physical carrier blocking pathogens from entering the body
Acts as chemical barrier by producing antimicrobial chemicals inhibiting growth of pathogens and can lower pH
How is mucous membranes a primary non-specific defence?
Protect body openings that are exposed to environment.
What do some membranes secrete?
Mucus
What is mucus?
A sticky substance that traps pathogens and contains antimicrobial enzymes
What are some body openings exposed to the environment?
Mouth Nostrils Ears Genitals Anus
What is a blood clot?
A mesh of protein (fibrin) fibres
How is blood clotting a primary non-specific defence?
Plugs wounds to prevent pathogen entry and blood loss
How are blood clots formed?
By a series of chemical reactions that take place when platelets are exposed to damaged blood vessels
What are platelets?
Fragments of cells in the blood
What are the signs of inflammation include?
Swelling, pain, heat and redness
What is inflammation triggered by?
Tissue damage
How does tissue damage trigger inflammination?
Damaged tissue releases molecules increasing permeability of blood vessels so they start to leak fluid to surrounding areas.
What does the leaking fluids to surroundings area do?
Swelling
Helps to isolate any pathogens
Cause vasodilation
What does vasodilation lead to?
Widening of the blood vessels increasing blood flow to affected area making areas got and being white blood cells to area fight off any pathogens present.
What is the skin able to do in event of injury?
Repair itself and reform a barrier against pathogen entry.
How is skin repaired?
Surface repaired by outer layer of skin cells dividing and migrating to edges of wound. Skin below wound then contacts to bring edged of wound closer together.
What is skin repaired with?
Collagen fibres
What causes a scar?
Too many collagen fibres
Name two repulsive reflexes?
Coughing and sneezing
When does a sneeze happen?
When mucous membranes in the nostrils are irritated by things such as dust or dirt.
What a cough stem from?
Irritating in the respiratory tract
What are both coughing and sneezing attempts at?
To expel foreign objects including pathogens from the body
What are expulsive reflexes?
Automatic
What are antigens?
Moles found on the surface of cells
What are antigens usually?
Proteins or polysaccharides
What happens when a pathogen invades the body?
The antigens on its cell surface are identified as foreign which activates cells in the immune system
What two types of stages does the immune response involve?
Specific and non-specific stages
Explain non-specific responses?
Happens in all microorganism whatever foreign antigens they have
Explain specific response?
Antigen-specific aimed at specific pathogens involving white blood cells called T and B lymphocytes
What is a phagocyte?
A type of white blood cell that carries out phagocytosis
What is phagocytosis?
Engulfment of pathogens
Where are phagocytes found?
In blood and in tissues and carry out non-specific immune responses
Basic stages of phagocytosis?
Recognises pathogen Engulf pathogen Pathogen in phagosome Lysosomes breaks down pathogen Phagocyte presents pathogens antigens
Explain recognition stage phagocytosis?
Phagocyte recognises antigens on pathogen
Explain engulfing stage phagocytosis?
Cytoplasm of phagocyte moves round pathogen engulfing it may be made easier by opsonins
What are opsonins?
Molecules in blood that attach to foreign antigens to aid phagocytosis
How do opsonins?
Some hide negative charge on membrane of pathogen making it easier for negatively-charged phagocytes to get closer to the pathogen
Explain pathogen contained stage?
Pathogen contained in phagosome (type of vesicle) in cytoplasm of phagocyte
Explain lysosomes step?
Lysosomes contains digestive enzymes fuses with phagosomes. The enzymes break down the pathogen
Explain phagocyte presents?
Phagocyte presents pathogens antigens sticking antigens on its surface to activate other immune system cells. When phagocyte does this by acting as antigen presenting cell
What are neutrophils?
A type of phagocyte the first white blood cells to respond to a pathogen inside the body.
What do neutrophils do near wounds?
Move towards them in response to signals from cytokinesis that acts as messenger molecules. Cytokinesis released by cells at site of the wound
What is a T-lymphocyte?
A type of white blood cell
What is the outside of the T lymphocyte covered with?
Receptors
What do the T lymphocytes receptors do?
Bond to antigens present by antigen-presenting cell (APC)
Are receptors on all antigens the same?
No each T lymphocyte has a different receptor on its surface
What can these receptors on T lymphocytes do?
Meet a complementary antigen it binds to it so each T lymphocyte will bind to a different antigen
What happens when each T lymphocyte binds to a different antigen?
T lymphocytes are activated in a process called clonal selection
What happens after clonal selection?
T lymphocytes undergo clonal expansion
What’s clonal expansion?
T lymphocytes divides to produce clones of itself
What do different types of T lymphocyte do?
Different functions
Name some T lymphocytes cells that are activated in clonal selection?
T helper cells
T killer cells
T regulatory cells
T Memory cells
What do T helper cells
Release substances to activate B lymphocyte and T killer cells
What do T killer cells do?
Attach and kill cells that are infected with a virus
T regulatory cells do what?
Suppress the immune response from other white blood cells to help stop immune system cells from mistakenly attaching the host’s body cells
What are B lymphocytes?
Another type of white blood cell
What are B lymphocytes covered in?
Proteins called antibodies
What do the antibodies on the B lymphocytes do?
Bind to antigens to form an antigen-antibody complex
True or false B lymphocytes have a similar shaped antigen on its surface?
False
B Lymphocytes have a different shaped antigen on its surface
What can a antibody of a B lymphocyte do?
Meet a complementary shaped antigen it binds to it so each B lymphocyte will bind to a different antigen
After each B lymphocyte has bonded to a different antigen?
Together with substances released from T helper cells activates the B lymphocyte (clonal selection
B lymphocyte clonal expansion?
Activated B lymphocyte divides by mitosis into plasma cells and memory cells
How do cells communicate?
Cell signalling
Explain cell signalling
Cell may release or present a substance that binds to receptors on another cell causing a response of some kind in the other cell
Why is cell signalling important in the immune response?
It helps activate all the different types of white blood cells needed
Give example of cell signalling?
T helper cells release interleukins that bind to receptors in B lymphocyte activating B lymphocytes
What are the helper cells signalling?
B lymphocytes that there’s a pathogen in the body
What is interleukins?
A type of cytokine
What are plasma cells?
Clones of B lymphocytes
What do plasma cells secrete?
Loads of antibodies specific to antigen into the blood
What do the antibodies bind to?
The antigens on the surface of the pathogen to form a lot antigen-antibody complexes
Name bits of antigens you need to know?
Variable region
Hinge region
Constant region
Disulfate bridges
What does the variable region of an antibody do?
Form antigen binding sites . Shape of region complementary to particular antigen. Variable region differs between antibodies
Describe hinge region?
Allows flexibility when antibodies bind to antigen
Describe constant region?
Allows binding to receptors on immune system cells e.g. Phagocytes. Constant region always the same in all antibodies
Disulfide bridges describe
Type of bond
Holds polypeptide chains of proteins together
Name three wars antibodies help to clear an infection?
1) agglutinating pathogens
2) neutralising toxins
3) preventing pathogen binding to human cell
agglutinating pathogens explain
Each antibody has 2 binding sites so antibody can bind to 2 pathogens at the same time. Pathogens become clumped together. Phagocytes bind to antibodies and phagocytose a lot of pathogens at once. (Agglutinins= antibodies behaving like this)
neutralising toxins explain?
Toxins have different shapes. Antibodies called anti-toxins bind to toxins produced by pathogens preventing toxins from affecting human cells so toxins neutralised. Toxin-antibodies complexes phagocytosed.
preventing pathogen binding to human cell explain?
When antibodies bind to antigen on pathogens they may block cell surface receptors that pathogens need to bind to host cells meaning pathogens can’t attach to or infect host cells.
Which is quicker primary or secondary response?
Secondary
What happens when a pathogen enters the body for the first time?
Antigens on surface activates the immune system (primary response)
Why is primary response slow?
They aren’t many B lymphocytes that make the antibody needed to bind to it.
What will the body eventually do? Primary response
Produce enough of the right antibody to overcome the infection. Meanwhile infected person shows symptoms of the disease.
What do T and B lymphocytes produce after exposed to an antigen?
Memory cells which remain in the body for a long time.
What will memory T lymphocytes?
Remember specific antigen and will recognise it a second time around
What will memory B lymphocytes do?
Record the specific antibodies needed to bind to the antigen
What will the person be after primary response?
Immune so immune system had ability to respond quicker to a swine infection.
What happens if the same pathogen enters the body again?
The immune system will produce a quicker, stronger immune response (secondary response)
Secondary response does clonal selection happen?
Faster
What happens to memory B lymphocytes secondary response?
Activated and divide into plasma cells that produce the right antibody to the antigen.
What happens to memory T lymphocytes secondary response?
Activated and divide into the correct type of T lymphocyte to kill cell carrying the antigen.
Secondary response often what?
Gets rid of pathogen before you begin to show any symptoms
Primary response
Pathogen enters for 1st time
Slow response
B and T lymphocytes activated
Symptoms
Secondary response
Enters for 2nd time
Fast response
Memory cells activated
No symptoms
What is a blood smear?
Sample of blood smeared over microscope slide
What are added to blood smears and why?
Stains to sample to make different cells easy to see
Likely to see what when looking at blood smear?
Red blood cell
White blood cell
Platelets
Do white blood cells have granules in their cytoplasm?
Some do some don’t
How to spot red blood cells?
No nucleus so easy
Neutrophil recognise?
Nucleus looks like three interconnected blobs (multi-loved). Cytoplasm is grainy
Lymphocyte recognise
Much smaller than neutrophil
Nucleus takes up most of the cell
Very little cytoplasm to be seen not grainy
Can’t tell if T or B lymphocytes under light microscope
Monocytes
Biggest white blood cell
Type of phagocyte
Kidney-bean shaped nucleus
Non-grainy cytoplasm
Active immunity
Your immune system makes own antibodies after stimulated by antigen
Active natural immunity
Become immune after catching disease
E.g. If you have measles as child you can’t catch it again
Active artificial
Become immune after given vaccination containing harmless dose of antigen
Passive immunity
Type of immunity you get from being given antibodies made from different organism- immune system doesn’t produce antibodies of its own
Passive natural
Baby become immune due to antibodies it receives from mother through placenta and in breast milk
Passive artificial
Immune after injected with antibodies from someone else e.g. Contract tetanus can be injected with antibodies against tetanus toxin collected from blood donation
Active immunity summary
Requires exposure to antigen
Take while to gain protection
Long term
Memory cells produced
Passive immunity summary
No exposure to antigen
Immediate protection
Short-term protection
No memory cells produced
What does an autoimmune disease involve?
An abnormal immune response
What causes an autoimmune disease?
Sometimes, an organism isn’t able to recognise self-antigens- antigens present on organisms own cells
When this happens, immune system treats self-antigens as foreign antigens and launched immune response against organism own tissue resulting in a disease called an autoimmune disease
Two examples of autoimmune diseases?
Lupus
Rheumatoid arthritis
Lupus describe
Caused by immune system attacking cells in connective tissues damaging tissues and causing painful inflammination. Lupus affects skin, joints and organs (heart)
Rheumatoid arthritis describe
Caused by immune system attacking cells in joints causing pain and inflammination
Autoimmune disease last and how can they be helped?
Usually chronic but often treated but not cured
What’s your immune system doing while you are suffering from a disease
While B lymphocytes are busy dividing to built up numbers to deal with pathogen (primary response)
What can vaccines do?
Help avoid you suffering from the disease
How do vaccines work?
By containing antigens that cause your body to produce memory cells against particular organisms without pathogen causing disease meaning immunity without symptoms
What happens if most people in a community are vaccinated?
Disease becomes extremely rare meaning people who haven’t been vaccinated are unlikely to get the disease because there’s no one to catch from (herd immunity)
What does herd immunity help prevent?
Epidemics, mass outbreaks of disease
What do antigens always contain?
Antigen may be free of attached or dead or attenuated pathogens
Attenuated means?
Weakened
Why are booster vaccines needed later on?
To make sure memory cells are produced
Vaccination and immunisation?
Vaccination administration of antigens in a vaccine into body
Immunisation is process by which you develop immunity
Link between vaccination and immunisation?
Vaccination causes immunisation
Name two routine vaccines offered to everyone?
MMR
Meningitis C vaccine
MMR describe
Protects against measles, mumps and rubella
Usually given to children as infection around a year old and before starting school
Contains attenuated measles, mumps and rubella viruses
Meningitis C virus describe
Protects against bacteria that causes Meningitis C
First given as injection to babies at 3 months
Boosters given to 1 years olds and teenagers
What happens to flu vaccine every year?
Changes because antigens on surface of influzena virus change regularly forming new strains of virus
Why does the flu vaccine have to change due to antigen flu virus changes?
Memory cells produced from vaccination with one stain of flu won’t recognise other strains with different antigens. Strains are immunologically distant
What happens every year flu strains?
Different influzena virus strains circulating in population so different vaccine has to be made
Laboratories do what for influzena?
Collect samples of different strains and organisations like WHO and CDC test effectiveness of different influzena vaccines against them
WHO
World health organisation
CDC
Centre for disease control
Who is a influzena vaccine chosen?
New vaccines are developed and one is chosen every year that is most effective against recently circulating influzena viruses
What must governments and health authorities?
Implement programmes of vaccination using most suitable vaccine. Sometimes people are given vaccine that protects from strain causing epidermis in another county helping stop strain spreading globally
What do your genes determine?
How your body responds to certain drugs
Different people respond to the same drug how?
In different way so makes certain drugs more effective for some people then others. So personalised medicines are a good idea.
Personalised medicines are?
Medicines tailored to individual DNA.
Theory behind personalised medicines?
If doctors have genetic information, they can use it to predict how you will respond to different drugs and only prescribe ones that will be most effective
What do scientists hope relating to personalised medicine?
By studying relationship between someone’s genetic make up and responsiveness to drugs the more effective drugs can be produced in the future
What does synthetic biology involve?
Using technology to design and makes things like artificial protein, cells or even microorganisms
Applications of synthetic biology?
Lots of different areas including medicine e.g. Scientists are looking at engineering bacteria to destroy cancer cells leaving healthy body cells intact
What are antibiotics?
Chemicals that kill or inhibit the growth of bacteria
When are antibiotics used by humans?
As drugs to treat bacterial infections. Useful because they can target bacterial cells without damaging human body cells
What was penicillin?
First antibiotic isolated by Alexander Fleming in 1928
Antibiotic use became widespread from?
Mid-twentieth century partly thanks to successful treatment of soldiers with penicillin in WW2
Past few decades we have dealt with bacterial infections?
Pretty easily using antibiotics causing death rate from infectious bacterial disease has fallen dramatically
What are some risks of antibiotics?
Can cause side effects, severe allergic reactions in some people, biggest risk is antibiotic resistance
Bacterial infections treatment in animals?
Antibiotics
What is their in the bacteria population?
Genetic variation
What makes some bacteria naturally resistant to antibiotics?
Genetic mutations
What is the ability to resist an antibiotic to a bacterium?
A big advantage
Why is the ability to resist an antibiotic to a bacterium a big advantage?
It’s better able to survive, even in a host who’s being treated with antibiotics to get rid of the infection and so it lives fit longer and reproduces many more times.
What’s does the host being the bacteria living longer and reproducing more times mean for the ability to resist an antibiotic?
Leads to the allele for antibiotic resistance being passed on to lots of offspring. Example of natural selection. This is how antibiotics spread and become more common in a population of bacteria over time.
What is the issue with bacteria being resistant to antibiotics for people?
People who become infected with these bacteria can’t easily get rid of them with antibiotics
What does increased use of antibiotics mean?
Antibiotic resistance is increasing. Superbugs that are resistant to most known antibiotics are becoming common meaning we are less able to treat potentially life-threatening bacterial infections.
Two examples of antibiotic resistant bacteria?
MRSA
Clostridium difficile
MRSA
Methicillin resistant Staphylococcus aureus
MRSA describe
Causes serious wound infections
Resistant to several antibiotics including meticillin
Clostridium difficile describe
Infects digestive system
Usually causing problems with people already treated with antibiotic
Thought to be harmless bacteria that are normally present in digestive system being killed off by antibiotics which C. difficile is resistant to
Allowing C. difficile to flourish
What symptoms does Clostridium difficile cause?
Produces a toxin causing diarrhoea, fever and cramps
What are two ways of overcoming problems of antibiotics?
Developing new antibiotics
Modifying existing ones
(Harder work to do than learning this lol)
Ways in which the likelihood of antibiotics resistance developing?
Doctors encouraged to reduce use of antibiotics
Patients advised to take all antibiotics they’re prescribed to make sure the infection is cleared and all the bacteria have been killed reducing risk of population of antibiotic-resistant bacteria developing
Doctors encouraged to reduce use of antibiotics examples?
Not to prescribe for minor infections
Not to prescribe to prevent infection (except for patients with already weakened immune system e.g. HIV sufferers, elderly)
How are many medicinal drugs manufactured?
Using natural compounds found in plants, animals or microorganisms e.g. Penicillin obtained from fungus
Some cancer drugs made from soil bacteria
Daffodils now grown to produce a drug used to treat Alzheimer’s disease
What proportion of organisms have been investigated so far?
Only a small proportion of organisms have been investigated so far, it’s possible that plants or microorganisms exist that contain compounds that could be used to treat currently incurable disease such as AID’s. Others may produce new antibiotics
What do possible sources of drugs need to be?
Protected by maintaining biodiversity on earth. If we don’t protect them some species could die out before we have a chance to study them
Even organisms studied could do what?
Prove to be useful sources of medicines as new techniques are developed for identifying, purifying and testing compounds
