immunity Flashcards
what are pathogens?
pathogens are microorganisms that cause disease
what are the chemical and physical barrier/non-specific response that protect you from pathogens?
- eyes - tears produce enzymes which kill bacteria/ wash out bacteria
- mouth - saliva cleans and removes bacteria
- nose - mucus traps bacteria
- lungs - tiny hairs cilia move mucus to the back of the throat
- stomach - hydrochloric acid kills bacteria
- skin - oil/sebum and dead cells make it difficult for pathogens to enter
- large intestines - bacteria in faeces prevent growth of pathogens
- reproductive system - acid conditions in the vagina prevent growth of pathogens
what is an antigen?
a protein located on the outer surface of cells that triggers the immune response/antibody production?
Antigens are…?
large complex molecules such as proteins, polysaccharides and glycoproteins and also chemical markers
where are antigens found?
the surface of pathogens/abnormal cells/ other organisms of the same species e.g tissues and organs
Why is this a problem with transplants?
the immune system recognises the tissue or organ as non-self eventhough they have come from individuals of the same species. and therefore attempts to destory the transplant
what are self antigens?
antigens on your cells
What are non-self antigens?
antigens which are not on your cells for example Bacteria, viruses or even cell from another human
When pathogens get pass the physica/chemical barrier…?
it causes
1. inflammation
2. Blood clots
3. Phagocytosis
function of white blood cells?
protect the body against infection
How many white blood cells do we produce in a day?
100 billion
Are there fewer rbc or fewer wbc?
for every 1 wbc there is 600 rbc’s
What are white blood cells also referred to as?
leukocytes
Two types of white blood cells?
phagocytes and lymphocytes
Role of phagocytes?
destroy invading microorganism by phagocytosis
Role of lymphocytes?
destroy invaders by producing antibodies
Two types of phagocytes?
neurophils and monocytes
role of Neurophils?
travel in the blood to infected sites where they engulf germs and fungi
Role of Monocytes?
capable of changing into hunting/macro-phages which destroy germs
What is phagocytosis?
the process by which phagocytes engul, ingest and digest pathogens
what type of process is phagocytosis?
non-specific, immediate response
Why is the pathogen not harmful to the phagocytes?
the phagocytes absorbs them
process of phagocytosis?
the phagocyte will recognise the antigen on the membrane of the pathogen as non-self
the phagocyte will engulf the pathogen so go through phagocytosis. The pathogen is wrapped in a membrane sac called a phagosome.
lysosome (vesicles containing digestive enzymes) move towards the phagosome containing the pathogen
the lysosome will fuse with the and lysozymes enzyme is released into it. this is called a phagolysome.
the enzyme hydrolyses the pathogen and kills it. harmless products of digestion are absorbed by the phagocyte.
what is antigen presenting?
The phagocytes sticks The antigens to its surface to activate the immune systems white blood cells
How do we minimise the effect of tissue rejection?
donor tissues is matched as closely as possible/ immunosuppressant drugs are administered
what type of cells does cellular immunity involve?
where do these cells mature in?
t- cells - mature in the thymus gland
Process of cell-mediated immunity?
pathogens invade body cells and are taken in by phagocytes
the phagocyte places antigens from the pathogen on its cell surface membrane and presents it to a t-cell
receptors on a specific helper T cell fit exactly onto the antigens as they are complimentary to antigen
the attachment activated the T helper cell to divide rapidly by mitosis and form a clone of genetically identical cells
After this the cloned T cells…?
develop into memory cells
stimulate phagocytosis
stimulate B cells to divide and secrete their antibody
activate cytotoxic cell
Memory T cells…?
remain in the body for a long time. they recognise the specific antigen which enables a quicker response if re-infected
Cytotoxic cells…?
attach to diseased cells in the body and release toxin to kill the cell and pathogen.
How do cytotoxic T cells kill infected cells?
they kill abnormal cells that are infected by pathogens by producing a protein called perforin that makes holes in the cell-surface membrane
How does Making holes kill the infected cells m?
The cell membrane becomes freely permeable to all substances and the cell dies as a result
What is humoral immunity?
where b lymphocytes respond to antigens presented on the cell membrane of a body cell
What do B cells produce?
a specific antibody that responds to one specific antigen
process of humoral immunity?
The phagocyte presents the antigen on its outer surface
B cells (lymphocytes) antibody on surface of cell is specific To the antigen as they’re complimentary. so the antibody attaches to the complimentary antigen.
the antigen enter the B cell by endocytosis and gets presented on the B cells surface After being processed
T helper cells bind to the processed antigen and stimulate B cells to divide rapidly by mitosis to form a clone of identical B cells called plasma cells (by clonal selection) and memory cells
After dividing by mitosis B cells form..?
plasma cells - primary immune response
memory cells - secondary immune response
Plasma cells..?
Are a clone of identical B cells that produce antibodies that is specific to the foreign antigen (clonal selection)
An Antibody is a protein found in the blood that is produced by plasma cells which binds to antigens as an immune response.
What is Agglutination?
The clumping together of Antigens caused by antibodies which assists phagocytosis. As there are more antigens in the same place, therefore phagocytes can locate them more easily.
Memory cells..?
remain in the body for a long time and recognise specific which enables a quicker response if re-infected
types of immunity
active (natural/artificial) and passive (natural/artifical)
what is active immunity?
individuals make their own antibodies by natural
active artificial - aquired after immunisation with a vaccine
what is passive immunity?
individuals get their antibodies already made e.g across placenta/ breast milk
howver passive artificial - aquired after injection with antibodies
what is a vaccine?
a dead otr inactive pathogen which activated the production of antibodies
what is attenuated vaccine?
a weakened strain of the pathogen
what is herd immunity?
even if individuals are not vaccinated they are less likely to catch the disease because there is fewer people to catch it from
explain the immune response?
latent period - time from infection to antibody production or time for complimentary b cells to collide with antigen
primary response -1st time contact to antigen
second response - 2nd exposure to the same pathogen
explain what happens in the first response?
takes 3-14 days to produce antibodies
- b cells divide to form a clone of plasma cells
- antibodies are produced rapidly then decrease as the antibody destroys the pathogen
- memory cells produced
-person is now immune
explains what happens in the second response?
- 2nd exposure to the antigen
- more rapid response
- memory cells collide more and bind to the antigen more
-memory b-cells divide to produce more plasma cells (more antibodies)
-memory t cells divide into the correct type of t-cell to kill the cell carying the pathogen - pathogens are destroyed even before symptoms are shownn
explain why this isnt the same case for flues or colds?
viruses constantly mutates, antigen variability
- so memory cells produced during the primary response will not recognise the different shaped antigens
what is hiv?
what does hiv stand for?
is a virus which effects your immune system specifically helper t-cells. so ypur immune system can no longer defend itself -aids
human immunodeficiency disease
what does aids stand for?
aquired immunodeficiency syndrome
bodily fluids with a high HIV concentration?
- blood
-semen - breast milk
-pus from sores
bodily fluids with a low concentration of HIV?
- sweat, tears, urine, saliva
how is HIV transmitted?
- sexually
-blood transfusions - infected mothers placentas/breast milk
Describe fully the process of how HIV replicates?
- HIV in blood cells attach to cells carrying the CD4 antigen, mostly t-cells
- the protein capsid fuses with the cell surface membrane . the RNA and enzymes of HIV enter the helper T-cell.
- The HIV transcriptase converts the virus’s RNA into DNA.
- The newly made DNA is moved into the helper T-cell’s nucleus where it is inserted into the cell’s DNA.
- The HIV DNA in the nucleus creates mRNA using the cell’s enzymes. This mRNA contains the instructions to making new proteins and the RNA to go into the new HIV
- The mRNA passes out of the nucleus through a nuclear pore and uses the cell’s protein synthesis mechanisms to make HIV particles
- The HIV particles break away from the helper T-cells with a piece of it’s cell surface membrane surrounding them which forms their lipid envelope.
How does HIV virus infect our cells?
- HIV in blood cells attach to cells carrying the CD4 antigen including t-cells and macrophages.
- after entering cell becomes a provirus in nuclear DNA
- it remains dormant but still being replicated for a long latency period (8-10) years
- eventually the virus re-assembles and emerges from the cell, killing wbc in the process
- this leaves the immune system severely compromised
explain how HIV affects helper t-cells
they use the t-cells organeels to make new HIV’s the new HIV’s are then released and go on to infect other t-helper cells
why is HIV called a retrovirus?
it possesses RNA and the enzyme reverse transcriptase which can make DNA from RNA - a reaction that is reverse of that carried out by transcriptase.
how does aids affect you?
- HIV causes AIDS by killing or interfering with the normal functioning of helper T-cells
- body can not fight infections so you usually die from diseases such as pneomia and tb
medication for HIV?
antiretroviral medication - slows down the progression from hiv to aids
why are antibiotics ineffective to HIV?
hiv is a virus which ivades our cells and antibiotics can not reach inside our cells
what is the ELISA test used for?
to detect and quantify a specific antigen (can be used to detect HIV and pathogens of diseases including TB and hepatitis)
ELISA test to give a positive result
Apply a sample to a surface, for example a slide to which all the antigens will attach.
1. Antigen is attached to a well.
2. Wash to remove any unbounded antigen
3. Add antibody which is complimentary To antigen
4. Wash to remove any unbounded antibodies
5. Add in second antibody which is complimentary to the first antibody and binds to it. The second antibody’s has an enzyme attached to it.
6. Wash to remove any unbounded antibody
7. Add colourless substrate of the enzyme. the enzyme acts on the substrate to change it into a coloured product
8. Intensity of colour change indicates quantity of antigen present.
what is an antibody? draw
where do you find antibodies?
- a protein that a b-cell secretes in response to a non-self antigen
structure - forms antigen-antibody complexes
- quaternary protein
- specific antigen binding site/ variable region
- 4 polypeptides
- Disulphide bridges
How does an antibody lead to the destruction of an antigen?
- immobilises the pathogen
- easier for phagocytes to detect and engulf invading cells
- inactivates the pathogen active region so it becomes less toxic
- they cause agglutination of bacterial cells, making it easier for phagocytes to locate them
what is a monoclonal antibody?
produced from a single group of genetically identical b-cells
uses of monoclonal antibodies
- medical diagnosis - preg tests, urine-drugs
- cancer treatment - anitibodies only attach to cancer cells and activate cytotoxic drug attached to the monoclonal antibody, only cancer cells killed by the drug
- transplant surgery - knock out specific t-cells which trigger rejection
ethical issues
- spleen of mouse is removed and deliberately given cancer
- there has been some deaths associated with monoclonal antibodies so patients must have full knowledge of risks
How are monoclonal antibodies used in pregnancy tests to give a positive result?
- pregnant women produce HGC hormone in urine
- the HCG binds to monoclonal antibodies with attached blue pigment - mobile phase
- the monoclonal antibodies move down along with the pigment and become immobolised
- some monoclonal antibodies are still mvoing down to the control strip and bind to the monoclonal antibodies on the control strip to show that the test is working
How can monoclonal antibodies be used to treat cancer cells via monoclonal antibody therapy?
- monoclonal antibodies are produced that are specific to antigens on cancer cells
- these antibodies are given to a patient and attach themselves to the receptors on their cancer cells
- they attach to the surface of their cancer cells and block the chemical signals that stimulate the uncontrolled growth
Explain the advantage of this?
since antibodies are not toxic and highly specific, they lead to fewer side effects than other therapies
DONE!!
