2c the immune system Flashcards
What is an antigen
Molecules that can generate an immune response when detected by the body
Found on the surface of cells used by immune system to identify pathogens
What is a pathogen
Organism that causes disease or abnormal body cells or toxins
what is a phagocyte
a type of white blood cell which carries out phagocytosis
found in blood and in tissues and are the first cells to respond in immune response
1–how do phagocytes work
1- recognise foreign antigens on pathogen
2-cytoplasm of phagocyte engulfs pathogen
3-pathogen now contained in phagocytic vacuole in cytoplasm
4-lysosome fuses with phagocytic vacuole , lysozyme breaks down pathogen
5- phagocytes then present the pathogen is antigen is it sticks the antigens on its surface to activate other immune system cells
what’s a lysosome
organelle that contains enzyme called lysozyme
2–describe phagocytes activating t cells
T cells have receptor proteins on surface which bind to complimentary antigens presented to it by phagocytes this activates the T-cell
How do you helper T cells respond
Release chemical signals that activates and stimulates phagocytes and cytotoxic T cells which kill abnormal foreign cells
Also activate B cells which secrete antibodies
What are B cells and T cells
Types of white blood cells
Describe B cells
covered with antibodies - proteins that bind antigens form an antigen-antibody complex
each B cell has different shape antibody on its membrane so form to different antigens
3–Describe how T cells activate b cells which divide into plasma cells
1) When antibody on the surface of the cell meets complimentary shaped antigen and they bind
2) this with substances released from helper T-cell is activate B-cell process called clonal selection
3) activated B cell divides into plasma cells
what are monoclonal antibodies
Plasma cells are identical to be cells secrete loads of antibodies specific to the antigen
How many binding sites does an Antobody have and what does this mean
Two so it can bind two pathogen is at same time meaning pathogen is become clumped together called agglutination
Phagocytes then bind to antibodies and phagocytose many pathogens at once process leads to destruction of pathogen is carrying this antigen in the body
what’s a cellular response
T cells and other immune system cells that they interact with
what’s a humoral response
B cells clonal selection and the production of monoclonal antibodies form the humoral response
describe primary response
When antigen enters body for first time
Response is slow as not many B cells present that can make Antibody needed to bind to auntigen
Body will then produce enough of right Antibody to overcome infection
B cells and T cells produce memory cells memory cells stay in body for long time
Person is now immune
Describe the cells and T cells in primary immune response
Memory T cells remember specific antigen and will recognise it a second time round
Memory B-cell is record specific antibodies needed to buy to antigen
Describe secondary response
If same pathogen enters body again immune system produces quicker stronger immune response
Clonal selection happens faster memory B-cell is activated dividing into plasma cells which produce right antibodies for antigen
Memory T cells activated dividing into correct type of T-cell to kill cell carying antigen
Gets rid of pathogen before person shows any symptoms
Describe vaccine
Contain antigens causing your body to produce memory cells against pathogens without pathogen causing disease meaning immunity without any symptoms
Describe herd immunity
Vaccine protecting individuals this reduces occurrence of disease therefore those who are not vaccinated also less likely to catch disease
What does vaccines contain
Antigens free or attached to a dead attenuated pathogen
What is disadvantage of taking vaccine orally
Could be broken down by enzymes in gut
or molecules of vaccine too large to be absorbed into blood
What are booster vaccines
Given later on to make sure memory cells are produced
What is antigenic variation
When pathogens change the surface antigen is different antigens are formed due to the changes in the genes of a pathogen
What are the strainss of influenza
Immunologically distinct
Why is the influenza vaccine changed every year
The strains are immunologically distinct meaning it has different antigens
What is active immunity
When your immune system makes its own antibodies after being stimulated by antigen
Describe natural active immunity
When you become immune after catching disease
Describe artificial active immunity
When you become immune after been given a vaccination containing harmless dose of antigen
What is passive immunity
Type of immunity you get from being given antibodies made by different organism
Describe natural passive immunity
When a baby becomes immune due to antibodies it receives from its mother placenta and breast milk
Describe artificial passive immunity
When you become immune after being injected with antibodies from someone else e.g. from blood donations
Difference in active and passive immunity
- Active immunity requires exposure to antigen( p doesn’t)
- takes awhile for protection to develop (p is immediate)
- memory cells are produced (not produced in p)
- protection is long-term as antibody is produced after activation of memory cells (p is short term antibodies broken down)
What are monoclonal antibodies
Antibodies produced from a single group of genetically identical be cells or plasma cells
meaning identical in structure
How are antibodies very specific
The binding sites have a unique tertiary structure that only one particular antigen can fit to
complimentary shape
How are monoclonal antibody is different
You can make them bind to anything you want
How are monoclonal antibody is useful for targeting cancer cells
Cancer cells have antigen is called tumour markers monoclonal antibody are made that bind to tumour markers
you can attach anti-cancer drugs to antibodies
antibodies come into contact with cancer cells they bind to tumour markers
meaning the drug will only accumulate in the body where they are cancer cells
therefore side-effects are low
What is the name of the hormone that pregnancy test detect
Human chorionic gonadotropin
hcg
How does a pregnancy test work
1-Application area contains antibodies for HCG bound to coloured blue bead
2-urine is applied any HCG binds to Antibody on beads forming antigen Antibody complex
3-urine moves up stick to test strip carrying beads with it
4-test stripped contains antibodies to Hache CG that are immobilised
5-if HCG present test strip turns blue as immobilised antibodies bind to any HCG concentrating the HCG Antibody complex with the blue beads attached
6-if no HCG present beads pass through test without binding
What is the ELISA test
Medical diagnostic test using antibodies
Allows you to see if patient has any antibodies to a certain antigen or any antigen to a certain antibody
what does ELISA stand for
Enzyme-linked immunosorbent assay
What is a direct ELISA test
Uses a single antibody that is complimentary to antigen your testing for
What is an indirect ELISA test
Uses two different antibodies
Method of an indirect ELISA test for HIV
…
Briefly describe the HIV
A virus that affects immune system eventually leading to Acquired Immune Deficiency Syndrome AIDS
Describe AIDS
Condition were immune system deteriorates and fails someone with AIDS is more vulnerable to other infections like pneumonia
How does HiV work
hIV infects and kills helper T cells which act as host cells for the virus
without helper T cells the immune system is unable to mount an affective response to infections as T cells activate phagocyte cytotoxic T cells and B cells
When does someone with HIV develop AIDS
When the helper T cells numbers in the body reach a critically low level
Describe HIVs core
The core contains genetic material RNA
and some proteins including the enzyme reverse transcriptase which is needed for virus replication
Describe HiV core outer coating
Outer coating of protein called capsid
What is the hiv extra outer layer around the capsid
Envelope made of membrane stolen from cell membrane of the previous Host cell
What is sticking out from envelope on HIv cell
Loads of copies of an attachment protein that helps HIV attached to host helper T cells
called envelope proteins
How does HIV virus replicate
HIV can only reproduce inside cells of the organism it’s infected
HIV replicates in helper T cells of the host
uses the equipment of the host cell to replicate
How does HIV replicates detailed
1-the attachment protein attaches to receptor molecule on cell membrane of helper T-cell
2-the capsid is released into the cell where uncoats and releases the RNA into the cell cytoplasm
3-in the cell reverse transcriptase used to make a complimentary strand of DNA from the viral RNA template
4-double-stranded DNA is made and inserted into human DNA
5-host cell enzymes used to make viral proteins from viral DNA found within human DNA
6-viral proteins assembled into new viruses which bad from cell and go on to infect other cells
What is the name of the periods where the person infected with HIV experiences no symptoms
Latency period which can last for years
What are the initial symptoms of AIDS
Minor infections of mucus membranes inside of nose ears or genitals
re-occurring respiratory infections
Describe mid stage of AIDS
As aids progresses number of the immune system cells decrease further
patients more susceptible to more serious infections like chronic diarrhoea severe bacterial infections and tuberculosis
Describe the late stages of AIDS
Patient has very low number of immune system cells can develop range of infections such as
toxoplasmosis of the brain a parasite infection
candidiasis of the respiratory system fungal infection these will likely kill patients
How does antibiotics kill bacteria
Interfering with their metabolic reactions target bacteria enzymes and ribosomes used in these reactions
Why can antibiotics kill bacteria
As bacteria enzymes and ribosomes are different for human enzymes and ribosomes meaning antibiotics only target bacterial ones and don’t damage human cells
Why can’t antibiotics kill viruses
Viruses don’t have their own enzymes and ribosomes they use Host cells
so antibiotics can’t inhibit them because they don’t target human processes
What do most anti-viral drugs target
The few virus-specific enzymes for example in HIV reverse transcriptase is targeted
the drug that targets this is called reverse transcriptase inhibitors
What are the best ways to combat HIV is
Anti-viral drugs can slow progression of HIV best way to control is reducing unprotected sex
HIv can be spread through infected bodily fluids e.g. blood from sharing needles and from HIV positive mother to fetus
How can HIV positive mothers have HIV negative babies
HIV positive mothers can take anti-viral drugs during pregnancy and reduce chances of baby having HIV
