Disease and the immune system Flashcards
What is a pathogen and what are its four types b
An organism that causes disease. Bacteria, viruses, fungi and protoctista.
What diseases does bacterium cause?
TB, Bacterial meningitis and ringrot
What diseases does virus cause?
HIV/AIDS, Influenza and Tobacco mosaic virus
What diseases does fungus cause?
Black Sigatoka, ringworm and athletes foot
What diseases does protoctist cause?
Potato/tomato blight and malaria
What are the two ways to spread a communicable disease?
Direct and indirect transmission
What is direct transmission? How?
A disease is transmitted directly from one organism to another.
Droplet infection, sexual intercourse or touching
What is indirect transmission? How?
When disease is transmitted from one organism to another via an intermediate.
Air, water, food or another organism (vector)
Name two diseases spread by direct transmission
HIV (sex) and Athletes foot (touch)
Name two diseases spread by indirect transmission
Potato blight (spores) and malaria (vectors(mosquitoes))
What three factors can affect disease transmission?
1) Living conditions
2) Climate
3) Social factors
How can living conditions affect disease transmission?
Overcrowded conditions can increase transmission - droplets in air remain for long periods of time
How can climate affect disease transmission?
1) Malaria more common in hot countries
2) Potato blight common during wet summers because spores need water to spread
How can social factors affect disease transmission?
1) Good health education means that people are informed about how it is transmitted and how it can be avoided
2) Good healthcare means there are more treatment options available
What barriers do animals have to prevent infection?
1) Skin
2) Mucous membranes
3) Blood clotting
4) Inflammation
5) Wound repair
5) Expulsive reflexes
How is skin a barrier to prevent infection?
Physical barrier that blocks pathogens from entering
How are mucous membranes a barrier to prevent infection?
Sticky substance trap pathogens
How is blood clotting a barrier to prevent infection?
Plug wounds to prevent pathogen infection
How is inflammation a barrier to prevent infection?
Swelling helps to isolate pathogens and increase blood flow to the area, bringing WBC
How is wound repair a barrier to prevent infection?
Skin reforms to prevent pathogen entry
How is expulsive reflexes a barrier to prevent infection?
Coughs and sneezes expel foreign objects
What barriers do plants have against pathogens?
1) Waxy cuticles provide a physical barrier
2) Plant cell walls provide a physical barrier
3) Callose (a polysaccharide) gets deposited at the plasmodesmata to limit spread of virus between cells
4) Antimicrobial chemicals kill pathogens
5) Chemicals secreted by plants toxic to insects
6) Pheromones can tell other plants to protect themselves and produce toxic chemicals
What are the four main stages in the immune response!
1) Phagocytes engulf the pathogen
2) Phagocytes activate T lymphocytes
3) T lymphocytes activate B lymphocytes which divide into plasma cells
4) Plasma cells make more antibodies to a specific antigen
What is a phagocyte?
A type of WBC that carries out phagocytosis
How does a phagocyte engulf a pathogen?
1) Phagocyte recognises the antigens on a pathogen
2) Cytoplasm moves round the pathogen and engulfs it
3) Pathogen is now contained in a phagosome
4) lysosome containing digestive enzymes breaks down the pathogen
5) phagocyte presents pathogens antigens to active other immune system cells
What are neutrophils?
A type of phagocyte that is the first WBC to respond to pathogens inside the body. They move towards a wound in response to signals from cytokines.
What is a T lymphocyte?
A WBC that’s surface is covered with receptors that binds to the antigens presented by the antigen presenting cells (phagocyte after it has finished engulfing and digesting pathogen)
What is clonal selection?
The activation of a T lymphocyte after it has bound with a complementary antigen
What is clonal expansion?
When a T lymphocyte divides to produce clones of itself
What are the different types of activated T lymphocytes?
1) T helper cells
2) T killer cells
3) T regulatory cells
What do T helper cells do?
Release substances to activate B lymphocytes and T killer cells
What do T killer cells do?
Attach to and kill cells that are infected with a virus
What do T regulatory cells do?
Suppress the immune response from other white blood cells to help stop immune system from attacking the hosts body cells
What do T helper cells release in the immune response?
Interleukins that binds to receptors on B lymphocytes to tell them that there’s a pathogen in the body
What are plasma cells?
Clones of the B lymphocytes that secrete loads of the antibody specific to the antigen in the blood
What is an antibody?
Glycoproteins that bind to antigens on the surface of pathogens
What is the structure of an antibody?
Two heavy and two light polypeptide chains that are bound together by a hinge region and have variable regions on top of the light chains for the site of antigen binding
What are disulfide bridges?
A type of bond that holds the polypeptide chains of the protein together
What is the constant region on an antibody?
A region that allows binding to receptors on immune system cells
What is agglutination?
When an antibody binds to two pathogens at the same time, clumping them together for a phagocyte to engulf them together
What is neutralising toxins?
Antibodies called antitoxins bind to the toxins to prevent infection him from affecting human cells
What are the three ways antibodies help to clear infection by?
1) agglutination
2) neutralising toxins
3) preventing the pathogen binding to human cells
Why is the primary response slow?
It has to go through all the processes of phagocytosis and the activiation of T and B lymphocytes before the pathogen is fully removed
Why is the secondary response faster?
Clonal selection will happen faster because the memory B and T lymphocytes are activated to kill the cell carrying the antigen
Does the patient experience symptoms in the secondary response?
No
What does a neutrophil look like?
Three interconnected blobs - multi-lobed nucleus and cytoplasm is grainy
What does a lymphocyte look like?
Smaller than a neutrophil and nucleus takes up most of the cell - little cytoplasm to be seen
What does a monocyte look like?
The biggest WBC with a kidney bean shaped nucleus and a non-grainy cytoplasm
What don’t RBC’s have?
A nucleus
What is active immunity? What are the two ways you can have it?
When your immune system makes its own antibodies after being stimulated by an antigen
1) Natural - immune after catching a disease
2) artificial - immune after vaccination that contains harmless dose of antigen
What is passive immunity? What are the two ways you can have it?
Immunity you get from being given antibodies made by a different organism (yours does not produce antibodies if its own)
1) Natural - baby becomes immune after drinking mothers milk / from placenta
2) Artificial - You become immune after being injected with antibodies from someone else
What is Auto immune disease (AIDS)?
When an organisms immune system isn’t able to recognise the antigens present on its own cells and treats them as foreign antigens, launching the immune response on its own tissue
What are two examples of aids and what are they?
Lupus- immune system attacking connective tissues
Rheumatoid arthritis- immune system attacking the joints
What do vaccines contain?
Antigens that cause your body to produce memory cells without causing disease
What is the difference between vaccination and immunisation?
Vaccination is the administration of antigens and immunisation is the process by which develop immunity.
Vaccination causes immunisation
Why do vaccines change?
The antigens on viruses such as influenza change regularly meaning that new vaccinations will need to be made
What do antibiotics do?
Kill or inhibit the growth of bacteria
What was the first antibiotic made?
Penicillin by Alexander Fleming
What is antibiotic resistance?
Genetic mutations that make some bacteria naturally resistant to an antibiotic
How is antibiotic resistance s problem?
The genetic mutation that has caused resistance is passed on to lots of offspring and antibiotics are ineffective to these
How is antibiotic resistance being aimed to be reduced?
By encouraging doctors to reduce their use of antibiotics - not prescribing for minor infections
Why is it important to maintain biodiversity?
Many medicinal drugs are discovered in manufacturing using natural compounds in plants
What are personalised medicines?
Medicines that are tailored to an individual DNA so that they are most effective for you
What is synthetic biology?
Using technology to design and make artificial proteins cells and microorganisms for medicine
