Unit 2 Cell Recognition and immune systems Flashcards
What is an infection?
It is an effect as well as an interaction between the pathogen and the body’s various defence mechanisms
Explain how an infection can be in 2 different ways?
1) Sometimes the pathogen can overwhelm the human defences and so the individual dies
2) Sometimes the human body defence mechanisms overwhelm the pathogen and the individual can recover so that when the pathogen infects for the second time, the body defences are better prepared and can kill the pathogen before any harm. This is immunity
Why are some vulnerable and other not due to the infection?
The young and elderly that are ill can be vulnerable as there defence mechanism is not fully fledged and a healthy individual is less likely to die from the same infection
What 2 longer-lasting defence mechanism involving a white blood cell are there?
Cell mediated responses involving T-lymphocytes
Humoral responses involving B-Lymphocytes
How does the body distinguish its own cells from foreign cells?
Each type of cell self (body’s own cells) and non-self (foreign cells) have specific molecules on its surface that creates an identity. These specific molecules are proteins that have a large variety and highly specific tertiary 3D structure that allows the cells to distinguish each other .
These 3D protein molecules allow the immune system to identify what 4 things?
1) Pathogens
2) Non-self materials from other cells or organisms of the same species
3) Toxins and pathogen produced toxins
4) Abnormal body cells such as cancer cellls
What is the relation between tissue rejection and identification of these cells?
Tissue or organ transplants allow cells from the same organism to be recognised as non-self despite being like human to human so to minimise this effect of rejection closely mathed relatives are used as donors as they are genetically close.
Also immunosuppressant drugs are used to reduce the effect of the immune system on these donor cells/ non-self cells
What is a common misconception about lymphocytes?
That they are produced when an infection is induced but actually all ten million different types of lymphocytes already exist
Why is it useful that there is a high concentration of lymphocytes during an infection?
There will be a higher probability of the protein molecule on the lymphocyte being complementary to the antigen on the pathogens surface.
What happens when there is an infection a second time in relation to the lymphocytes and pathogens?
The lymphocye with the specific protein molecule o n its surface will be stimulate to produce more of itself so that it can substantially overcome (the reson why there is a lag time between production and exposure to a pathogen)the pathogen and therefore destroy it, this is called clonal selection
How is it that from an early stage the lymphocytes in the body are recognised every single cell?
In the fetus, the lymphocyes are constantly colliding with other cells and it is rare to have an infection in the fetus because it is protected by the placenta from the outside. Therefore all the lymphocytes with the specific protein molecule will be complementary to all the cells in the fetus and those that are not will just die out. The only exception is the lymphocytes that have a specific protein molecule that is complementary to a non-self cell.
How do the lymphocytes in adults work?
In adults the lymphocytes are found in bone marrow so so initially they only encounter self-antigens, if lymphocytes encounter self-antigens and produce an immune response then these lymphocytes undergo apoptosis in which they self-destruct before differenmtiation into mature lymphocytes.
As a result there is no versions/clones of these anti-self lymphocytes (self-destruct lymphocytes) in the blood
What are the chemical defence mechanism consisting of?
Lymphocytes and Phagocytes
What are Phagocytes?
Phagocytes are a type of white blood cell that ingest pathogens and destroyting them in a process called phagocytosis before it can cause any harm
What are Lymphocytes involved in?
Lymphocytes are involved in the immune responses
What is an antigen?
Any part of an organism or substance that is recognized as non-self (foreign) by the immune system
What is the relation between antigens and microorganisms?
Antigens are proteins that are a part of the cell-surface membrane or cell-walls of invading cells such as cancer cells
What does the presence of an antigen allow the immune system to do?
To trigger an immune response via the the production of antibodies as part of the body’s defence system
What type of response is Phagocytosis?
A non-specific response
What is the difference between specific responses to non-specific responses?
Specific responses react to specific antigens and are slower in action but provide long term immunity
What do specific immune responses rely on and where are they found?
Type of white blood cell such as lymphocytes produced by the stem cells in bone marrow
What are the 2 types of Lymphocytes?
B-Lymphocytes and T-Lymphocytes
How do B-Lymphocytes work?
B-lymphocytes mature in the bone marrow and are associated with humoral immunity involving antibodies that are present in bodily fluids such as blood plasma
How do T-Lymphocytes work?
T-lymphocytes mature in the thymus gland and are associated with cell-mediated immunity which is the immunity involving body cells
What do lymphocytes respond to?
They respond to another lymphocyte when it has been infected by a foreign / non-self body and also respond to another lymphocyte of the same species because they are gentically different
What 2 lymphocytes of the same species that allow them to be distinguished?
They have the different antigens collectively to the the pathogen so they can be distinguished
What are the 2 ways that lymphocytes are able to distinguish themselves from the pathogens?
Phagocytes that have engulfed and hydrolysed an a pathogen have some of the pathogen’s antigen present on the surface of the cell membrane
Body cells invaded by a virus present some of the virus antigens on their cell-surface membrane
What are the 2 other ways that lymphocytes are able to distinguish themselves from the pathogens?
Transplanted cells from individuals of the same species have different antigens on their cell surface membrane
Cancer cells have antigens on their cell surface membranes which are different to normal body cells
What are antigen presenting cells?
Cells that present the antigens of foreign / non-self particles on their cell surface membrane
What is the cell-mediated response?
In which T-lymphocytes only respond to the antigens present on a body cell rather than to the antigens within the bodily fluids
What is the cellular response also known as?
Cell-mediated response
What are the 5 main stages of the role of a T cell?
1) Pathogens invade body cells or are taken in by phagocytes
2) The phagocyte places the pathogen’s antigens on the cell-surface membrane of itself
3) Receptors of a specific helper T cell binds exactly to one of these antigens
4) The attachment of the T cell to an antigen allows the T cell to rapidly divide by mitosis and form a clone of genetically identical cells
5) These gentetically identical cells can develop into 4 stages
What are the 4 stages that a cloned T cell can develop into?
1) Develop into memory cells that enable a quick response to future infections by the same pathogen
2) Stimulate phagocytes to engulf pathogens by Phagocytosis
3) Stimulate B cells to divide and secrete their antibody
4) Activate cytotoxic T cells
What are cytotoxic cells?
Cytotoxic cells kill abnormal cells and body cells that are infected by pathogens producing a protein called perforin that makes holes in the cell-surface membrane
What do the holes made by perlofin that makes holes in the cell-surface membrane mean?
The holes in the cell-surface membrane allow the cell membrane to be freely permeable to all substances so the cell dies
What does the importance of cell surface membranes allow?
It allows the integrity of cell surface membranes and therfore it aids the survival of cells
This action of T cells turning into cytotoxic cells is important due to what?
It allows the prevention of viruses using body cells as hosts so that they can be multiplied and divided infecting more cells
What does humour actually biologically mean?
Body fluids
What is humoral immunity?
It involves antibodies soluble in the blood and tissue fluid in the body
What do each B-cell have that it is complementary to the pathogen’s antigen?
B-cells have an antibody that is complementary to the pathogen’s antigen within the blood or tissue fluid
What is the process of which B-cells antibody collides with the pathogen antigen and how does it work
The antibody attaches to the complementary and specific antigen via endocytosis and so the antigen is expressed on the cell-surface membrane of the B-cell allowing the B-cell to divide rapidly by mitosis and therefore start to clone
What is clonal selection?
In which the antibodies of a cell attach with the antigen to allow the cloning of the same genetically identical cells which allows the faster response to a vast number of antigens during another encounter
When B-cells make clones of themselves what does this mean that they produce?
The genetically identical cloned B-cells produce monoclonal antibodies
As well as producing monoclonal antibodies what else does the B-cell clone produce?
The cells produced are then into 2 other types of cells - plasma and memory cells
What are plasma cells and how do they work?
Plasma cells secrete antibodies into blood plasma , they make about 2000 antibodies every second and last only a few days. They are responsible for the immediate defence against the body
What is the initial production of antibodies and memory cells called?
The primary immune response
What is the secondary immune response?
The secondary immune response uses memory cells that last longer and produce antibodies not directly but into the blood and tissue fluid so that when these antibodies interact with the pathogen’s antigen they are producing more memory cells and plasma cells
What is the result of the immune system in relation to the secondary immune response?
The secondary immune response produces the antibodies and memory cells at a faster rate so that the pathogen is defeated much faster so that the individual is not ill or is ill for a shorter amount of time
What are the 7 main stages of a B-cell?
1) The surface antigens of a pathogen are taken up by B-cells
2) The B-cell processes the antigens and expresses them on the surface cell membrane
3) Helper T cells are attached to the antigens on the cell-surface membrane and activate the B-cell
4) The B-cells is now rapidly dividing via mitosis to give a clone of plasma cells
5) The cloned and genetically identical plasma cells produce and secrete the specific antibody that is complementary to the pathogen’s antigen
6) These antibodies attach to the antigen and destroy them
7) Some B-cells are developed into memory cells so they can respond to future infections by the same pathogen by dividing rapidly and therefore developing into plasma cells to produce antibodies
What is antibody in detail?
An antibody is a protein with specific binding sites made by B-cells
Explain the antibody binding sites?
An antibody has 2 binding sites which are complementary to the pathogen’s specific antigen
How is it possible to have a vast variety of antibodies?
Antibodies are made up of proteins which are molecules that occur in an infinite amount of atoms
What are antibodies made up of ?
They are made up of 4 polypeptide chains in which the chains of one pair are long and are called heavy chains while the chains of the other pair are called the light chains
What is the antibody-antigen complex?
When the antibody has a specific binding site to which the it attaches to a specific antigen
Why is the binding site of the antibody known as a variable region?
The binding sites of an antibody are considered to be changeable for every antibody
What does each antibody binding site consist of?
Each antibody binding site consists of amino acid sequences that form a specific 3D shape that directly binds to the complementary antigen
Other than the heavy and light chains, binding site what is the rest of the antibody known as?
The constant region
What does the constant region bind to?
The constant region binds to the receptors on cells such as B-cells
What is a common misconception about antibodies and antigens?
Antibodies kill the antigens when they actually just prepare the antigens for their destruction
What are the 2 ways in which an antibody is used to destroy the bacteriums
The antibody can cause the alggutination of the bacterial cells so that clumps of bacterial cells are formed making it easier for phagocytes to locate them
They serve as markers that stimukate the phagocytes to engulf the bacterial cells to which they are attached
How are monoclonal antibodies used to treat cancer cells?
Monoclonal antibodies are used to be attached to the specific cancer cell antigens
These antibodies are attached to the receptor on the cancer cells
These monoclonal antibodies attach to the surface of their cancer cells and block the chemical signals that stimulate their uncontrolled growth
Give an example of a monoclonal antibody and the cancer it treats?
Herceptin is used to treat breast cancer this type of treatment is called the direct monoclonal antibody treatment
What is an advantage of direct monoclonal antibody treatment?
The antibodies are not toxic and highly specific whcih leads to fewer side effects than other forms of therapy
Describe the indirect monoclonal antibody therapy?
Attaching a radioactive or cytotoxic drug to the monoclonal antibody so that when the monoclonal antibody attaches to the cancer cells the cancer cell is destroyed
Why are monoclonal antibodies used in smaller doses?
Monoclonal antibodies are used as they are cheaper and also reduces any side effects the drug may have
How can a monoclonal antibody help identify the prostate cancer levels in the body and how does this work?
Prostate cancer produces a protein called PSA (prostate specific antigen) which leads to high level of that protein in the blood so allowing that antibody to attach to PSA will allow it to be able to measure the level of PSA in the blood so that it can give a warning about the need for further diagnostic tests
Describe the relation between the pregnancy test and the monoclonal antibodies?
These tests rely on the hormone produced by the placenta called the human chorionic gonadatrophin (hCG) this is detected in the mother’s urine. This monoclonal antibody that is specific to hCG is attached to some coloured dyes so that when the hCG is present the colour dyes indicate this
What are the ethical issues that are raised with the production fo Monoclonal Antibodies?
Monoclonal antibodies are produced via the mice producing producing both antibodies and tumour cells which have been injected into the mice which can cause the suffering
What are the ethical issues about the patient using the monoclonal antibodies?
The patient is sometimes not told about the major risks or even benefits which allowed some cases of using monoclonal antibodies that lead to multiple sclerosis
What are the ethical issues about using human test subjects on trial for use on monoclonal antibodies?
Testing for the safety and dosage of drugs in which 2006 six volunteers took place in a trial of anew monoclonal antibody and were diagnosed with organ failur within the first few minutes of taking the newly proposed monoclonal antibody
Explain the first 4 steps of producing monoclonal antibodies?
1) A mouse is exposed to non-self material to the point that an antibody is required
2) The B cells in the mouse produce a mixture of antibodies which are extracted from the spleen of the mouse
3) To allow these B cells to divide outside of the body these B cells are fused together with a cancer cell
4) The detergent is added to the mixture to break down the cell-surface membrane of both types of cell to allow the cancer cell and the B cell to fuse together to form hybridoma cells
Explain the last 4 stages of producing monoclonal antibodies?
5) These monoclonal antibodies are separated under a microscope and each single cell is cultured to form a clone, in which each clone is used to test if it is producing the required antibody
6) Any clone that is producing the specific antibody for the cancer cell antigen is then mass-produced and the antibodies are extracted from the growth medium
7) Since these antibodies come from a single clone of a single B cell they are called monoclonal antibodies
What are the 4 type of immunity?
Passive immunity
Active immunity
Natural active immunity
Artificial active immunity
What is passive immunity?
Immunity that is produced by the introduction of antibodies into indiciduals from an external source. There is no direct contact between antibodies and the antigens of the pathogens
Give 2 examples of passive immunity?
The immunity that is passed from the mother to the child / embryo in the placenta
The immunity that is given to an individual when there is an interaction bteween anti-venom
What is active immunity?
Stimulating the production of antibodies by the individuals own immune system when there is direct contact involved with a pathogen’s antigen and the antibodies of the individual
What are the 2 types of Active immunity?
Natural and artificial immunity
What is Natural immunity?
The immune system acting under normally infected conditions in which it produces antibodies due to a natural stimulus
What is artificial immunity?
The immune system has an induced immune response from a vaccination without the individual suffering from the response
What is a vaccine?
An artificial stimulus via the mouth or the body in which the body is stimulated by a variation of one or more antigens
During the infection during a vaccination what is a key factor?
Memory cells are the key factor produced during the infection or stimulation of a vaccine as they allow the mass production of T cells and B cells to prevent any signs of illness for the individual
What are the successes of a vaccination shown by?
Economically available to sufficient of the populations as they can be immunised
Less side effects so there is more of the populations volunteering to be immunised
Methods of producing, storing and transporting the vaccine should be able
Hygienic conditions and refrigerated support
Appropriate staff with administering skills should be employed in the vaccine sectors across the area
Vaccination of the whole population so that herd immunity is established
Explain what and how herd immunity works?
Herd immunity is when most of the population is immunised so that the few individuals that are not will have a lower risk to getting and transmitting the disease to others as the spread is lowered as the majority are immunised
What is the advantage of herd immunity?
Herd Immunity allows the large population to remain stable since it is very difficult to immunise everyone in the population because if they were ill and were vaccinated the immune system would be able to defend against the disease as well as the disease could adapt and evolve into a mutated disease so it helps to prevent these 2 factors
What happens to the influenza virus that allows it to mutate?
The influenza virus has the antigenic variability which allows it to change its antigens frequently so that the antibiotics and vaccines are unable to catch up with its evolutions and adaptations
What are the 7 ethics of using vaccines?
1) Use of animals for trial
2) Should individuals be used for volunteering to test
3) Accepting the risk in the interests of public health
4) Trialling the unknown vaccine in a poor country with the most of the disease is located
5) Religious and personal belief and medical grounds what age range should have the treatment or vaccine
6) Priority for other diseases and money sacrificed for larger projects such as cancer
7) Individual health risks vs controlling the public health of a population at a large sector
Explain the process of how HIV replicates within the human body?
1) HIV enters the body and circulates in the blood
2) A protein of HIV readily binds to a protein called CD4
3) HIV most readily attaches to the T-Helper Cells
4) The HIV reverse transcriptase converts the Virus’s DNA from RNA
5) The newly made DNA moves into the T helper cell’s nucleus inserted into the cell’s DNA
6) HIV DNA makes mRNA in the nucleus using cell enzymes
7) The mRNA passes out of the nucleus via a nuclear pore so that via protein synthesis it can make HIV particles
8) HIV particles break away from the human cell leaving behind the protein coat on the cell-surface membrane
How are new viral proteins made during the HIV replication within the human body?
The mRNA contains instructions for making the viral proteins and new RNA for the Viral cell
How HIV causes the symptoms of AIDS?
HIV attacks the T helper cells so there is a reduction of 800-1200 mm-3 of cells to 200 in each mm^-3 of blood which means they can’t stimulate the B-cells to produce enough memory cells or cytotoxic cells to destroy the pathogen based human cells. As a result the immune system is now relatively vulnerable to other diseases. Over times this can lead to the causation of AIDS
What is ELISA?
Enzyme Linked Immunosorbant Assay which can detect the presence of a protein which in a sample and the quantity
How is the technique for analysing ELISA work?
1) Apply the sample for the surface
2) Wash the surface (glass tile or slip) so that there is
