Module 2 : Cell Recogintion And The Imune System Flashcards
What is a pathogen?
Microorganisms that cause diseases.
What is a communicable disease?
An infectious disease that can be passes form one organism to another. They are caused by microorganisms known as pathogens.
What are the four main types of pathogen?
Bacteria, viruses, protoctists and fungi.
Why can bacteria be considered a pathogen?
They produce toxins that can damage body cells.
Why can viruses be considered a pathogen?
They use host cells to replicate before bursting out and destroying cells.
Why can protoctists be considered pathogens?
They take over cells and break them open.
why can fungi be considered pathogens?
They digest living cells to destroy them and some produce toxins.
What is a non-specific defence?
These act quickly to defend the body, but response in the same way for all pathogens.
What is a specific defence?
These are slower to decent the body but produce a specific response for each pathogen.
Why is the skin considered a physical barrier form pathogens?
It blocks the pathogens from entering the body.
Why is the skin considered a chemical barrier form pathogens?
It produces sebum, an oily, anti microbial substance that lowers the pH to inhibit the growth of pathogens.
What is a mucous membrane and how does it defend agains pathogens?
Parts of the ear,nose,throat and digestive tract are lined by mucous membranes.
These membranes secrete mucus to trap pathogens and use lysosomes to destroy they.
How do expulsion reflexes help to defend against pathogens?
Coughing and sneezing are methods of expelling foreign objects from the gas exchanging system.
Vomiting and diarrhoea expel the contents of the gut along with any pathogens present.
How does blood clotting and wound repair defend the body agains pathogens?
A cut to the skin provides a possible entry for pathogens and so blood clots act quickly to seal any wounds. The clot dries out the form a scalp that blocks entry to the body. After a scab has formed the skin is capable of repairing itself to reform its physical barrier. Epidermal cells underneath the scalp divide while damaged blood vessels regrow and collagen fibres are used to provide strength to the new tissue. Once the epidermis is the required thickness, the scalp breaks off and the wound is healed.
What is inflammation?
Consists of swelling, heat, redness, and pain at the site of infection or wounds.
What are the two ways that inflammation on can be triggered by damaged issues which release chemicals affecting the blood vessels?
- blood vessels dilate which increases blood flow to the area, making it hotter to prevent pathogens from reproducing.
- blood vessel walls become more permeable so that they start to leak tissue fluid, causing swelling and isolating any pathogens in the damaged tissue.
What is an antigen?
They are unique molecules (usually proteins) that can be found on the surface of cells.
What do antigens do in the immune system?
They allow the immune system to distinguish between the body’s own cells and foreign cells. Any foreign cells can be destroyed whilst leaving the body’s own cells unaffected.
What is phagocytosis?
A type of non-specific defence involving a type of cell known as a phagocyte.
What do phagocytes do?
A type of white blood cell that engulf and destroy pathogens. They are found in the blood and body tissues of many organisms.
How is the process of phagocytosis carried out?
- The pathogen releases chemicals that attract the phagocyte.
2.the phagocyte recognises the pathogens antigen as non-self. This causes the phagocyte to bind to the pathogen.
3.the phagocyte engulfs the pathogen. - The pathogen is now contained within a vesicle known as a ‘phagosome’.
5.the lysosome, containing hydrochloride enzymes called lysozymes, fuses with the phagosome to form a phagolysosome. - Lysozymes digest and destroy the pathogen.
- The phagocyte presents the pathogens antigens on its surface to active at other cells in the immune system. The phagocyte is then referred yo as an antigen presenting cell (APC).
What are specific defence mechanisms?
Slower than non-specific defences, but they produce a unique response for each type of pathogens. They also provide long-term immunity against specific pathogens.
What is the specific immune response dependent on?
Lymphocytes.
What is a T lymphocyte?
Also known as T cells. They mature in the thymus gland. They are involved in their cellular response where they respond to antigens presented on the body cells.
What is a B lymphocyte?
Also known as B cells. They mature in the bone marrow. They are involved in the humoral response where they produce antibodies found in body fluids.
What are Th cells?
These cells have receptors on their cell-surface that bind to complimentary antigens on antigen presenting cells. After binding, they can form memory cells, stimulate B cells or phagocytes, and activate cytotoxic T cells.
What are Cytotoxic T cells?
These cells kill abnormal and foreign cells by producing a protein known as performing. This protein makes holes in the cell-surface membrane, causing it to become freely permeable and causing cell death.
What are Memory T cells?
These cells provide long-term immunity against specific pathogens. They provide a rapid response if the body is re-infected by the same pathogen.
What are the stages of the cellular response?
Phagocytes engulf pathogen and display their antigens on the cell-surface. They are known as antigen-presenting cell.
Helper T cells with complimentary receptors bins to these antigens.
On binding, the helper T cell is activated to divide by mitosis to from genetically identical clones.
Why do cloned T cells develop into memory cells?
These circulate in the body to provide long-term immunity.
Why do cloned T cells stimulate phagocytosis?
Cloned cells stimulate phagocytosis to engulf pathogens.
Why do cloned T cells stimulate division of B cells?
Cloned cells stimulate b cells to divide and produce antibodies.
Why do cloned T cells activate cytotoxic T cells?
The allows Tc cells to kill infected cells.
What is the humoral response?
The humoral response is one of the specific defence mechanisms used to protect the body for disease. It involves the production of specific antibodies to destroy pathogens.
Which cells are involved the humoral response?
The humoral response involves the use of B lymphocytes or B cells. B cells produce and are covered in proteins known as antibodies. It is called the humoral response as antibodies are found in body fluids, which are otherwise known as ‘humors’.
How are B cells involved in the humoral response?
- these cells have antibodies on their cell-surface membrane that bind to complimentary antigens.
- on doing so , they engulf the antigens and display them on their cell-surface to become antigen-presenting cells.
- once activated, B cells can divide into plasma cells and memory cells.
How are plasma cells involved in the humoral response?
- these are types of B cells that can produce and secrete antibodies angiostatin a specific antigen.
- they have a short lifespan of only a few days.
How are memory cells used in the humoral response?
- these are types of B cells that provide long-term immunity against specific pathogens.
- that have a much longer lifespan than plasma cells.
- they rapidly divide into plasma cells if the body is re-infected by the same pathogen.
How are helper T cells used in the humoral response?
- these cells bind to antigen-presenting cells to activate the division of B cells.
What are the stages of the humoral response?
- A B-cell with a complimentary antibody binds to the antigens on a pathogen.
- The B-cell engulfs the pathogen and presents its antigens on the cell-surface membrane to become an antigen-presenting cell.
- Clonal selection - Activated T helper cells bind to the B-cell, causing activation of this B-cell.
- Clonal expansion - The activated B-cell divides by mitosis to from plasma and memory cell clones.
- The cloned plasma cells produce and secrete the specific antibody which is complementary to the antigen on the pathogens surface. These antibodies attach to antigens on pathogens and destroy them.
- The memory cells circulate the blood an tissue fluid, ready to divide if the body is re-infected by the same pathogen.
What is the difference between Clonal Expansion and Clonal Selection?
In clonal expansion the division of specific
B cells to produce genetically identical clones. In clonal selection the B cell with the correct antibody is selected for cloning.
What is the primary immune response?
This takes place when the body is exposes to a pathogen for the first time. This response is slow and the infected individual experiences symptoms of the disease.
What is the secondary immune response?
This takes place when the body has been exposed to the dame pathogen before. This response is much faster and stronger and pathogens are destroyed before any symptoms appear.
What do antibody’s look like?
They have a Y-shaped glycoprotein made up of four polypeptide chains, two heavy chains and two light chains.
What is the contrast region of an antibody?
This is the same for call antibodies and binds to receptors E on cells such as B cells.
What is the variable region of antibodies?
This is different for each antibody as its shape is complimentary to a specific antigen. This is the part of the antibody that binds to antigens.
What is agglutination of pathogens in antibodies?
This involves clumping pathogens together to enable easier phagocytosis.
Antibodies act as agglutinins, causing pathogens to clump together. This makes it easier for phagocytes to locate pathogens and allows them to engulf a number of pathogens at once.
What is neutralisation of toxins with antibodies?
This is when antibodies bins to toxins to inactivate them.
Antibodies can act as antitoxins where they bind to toxins produced by pathogens. This binding neutralises the toxins to prevent them form damaging body cells.
What is preventing pathogens form binding with antibodies?
This is when antibodies bind to pathogens to stop them form infecting body cells.
When antibodies bind to a pathogens antigens, they block cell-surface receptors needed to bind to host cells. This means that the pathogens cannot bind to or invade host cells.
How can you use monoclonal antibodies to diagnose disease?
Monoclonal antibodies bind to specific cell types to identify infected cells.
How can you use monoclonal antibodies for the treatment of disease?
Monoclonal antibodies bind to specific calls, bringing therapeutic drugs with them.
How can monoclonal antibodies be used for pregnancy testing?
Monoclonal antibodies bind to a pregnancy hormone in home pregnancy testing kits.
How can monoclonal antibodies be used to detect certain cancers?
Monoclonal antibodies can bind to prorate specific antigens for example, to identify prostrate cancer in men.
What is an ELISA test?
The Enzyme Linked ImmunoSorbant Assay test uses monoclonal antibodies to detect both the presence and quantity of protein in a sample. It is often used to find out weather a patient has antigens for a pathogen, and hence has the disease.
What are the two types of ELISA test?
The direst test - this uses only one antibody.
The indirect test this uses two antibodies.
What are the stages of carrying out an indirect ELISA test?
- Add the sample to a well plate where the target protein can attach to the well.
- Add the antibody that is specific to the target protein. These antibodies will bind to the target proteins attached to the well.
- Wash the well to remove any unbound antibodies.
- Add a second antibody that will bind to the first antibody. These secondary antibodies are attached to an enzyme.
- Wash the well again and remove any unbound secondary antibodies.
- Add a solution containing substrate to the well. The enzyme attached to the secondary antibody will act on the substrate to cause a colour change. The intensity of the colour indicated the quantity of protein present.
What is active immunity?
- this type of immunity develops when the immune system make it’d own antibodies after exposure to a pathogens antigens.
- it take a while to become immune to the disease, but it is long-term protection because memory cells are produced.
What is passive immunity?
-this type of immunity develops when and individual is given antibodies made by different organisms.
- this method provided immoderate immunity to the disease, but it is short-term protection because the antibodies are Brocken down and memory cell are not produced.
What is a vaccination?
The involve the introduction of a pathogens antigens into the body’s, usually via injection. This stimulated the body to produce an immune response to the pathogen and in doing so, allows the body to develop artificial active immunity.
What may vaccines contain they will stimulate an immune response?
- dead or inactive pathogens.
- attenuated pathogen strains.
- a harmless version of a toxin
- isolated antigens from a pathogen.
- genetically engineered antigens.
What are the main steps of a vaccination?
- The vaccine, containing antigens, is injected into the blood.
- This stimulates the primary immune response to produce antibodies against the pathogen.
- Memory cells, capable of recognising these antigens, are produced.
- On second exposure to this pathogen, memory cells rapidly divide into plasma cells.
- Plasma cells rapidly produce antibodies again the pathogen,
- Th E pathogen is destroyed before any symptoms are experienced.
How can availability effect how successful a vaccination program is?
Suitable vaccines must be affordable and available in large amounts for mass immunity.
How does having minimal side effect determine how effective a vaccine is?
The fewer the side effects form the vaccine, the ester the public accepts it.
How does infrastructure determine how successful a vaccine is?
Necessary resources for producing, storing, and transporting the vaccine are essential, including advanced technology and refrigeration.
How does administration determine how successful a vaccine is?
Proper and timely vaccine administration is important, requiring trained healthcare workers.
How does her immunity determine how successful a vaccine is?
The goal is to vaccinate the majority of the population to achieve hear immunity.
Why might individual immunity failures prevent the elimination of a disease?
People with weak immune systems may not be able to withstand vaccines, or may not develop an immune response.
Why might pre-immunity infection prevent the elimination of a disease?
Some individuals might contract the disease post-vaccination but before immunity develops, becoming potential disease reservoirs.
Why might pathogen mutation and antigenic variability prevent the elimination of a disease?
Rapini antigenic changes due to frequent mutations can mean vaccines ineffective, as the immune system can no longer recognise the pathogens new antigens.
Why might pathogen variety prevent the elimination of a disease?
With disease like the common clod, the sheer number of pathogen variants can make developing a universally effective vaccine nearly impossible.
Why might pathogen hiding prevent the elimination of a disease?
Certain pathogens can evade the immune system by ‘hiding’ inside cells or inhabiting hard to reach body regions like the intestine.
Why might vaccine objections prevent the elimination of a disease?
Personal, religious, ethical, or medical objections to vaccinations can hinder disease eradication. Misinformation can lead to reduced vaccination rates.
What is a live attenuated vaccine?
Modifies strain which multiplies a bit but is not pathogenic.
What is a recombinant vector vaccine?
Genes for antigen are transferred to a harmless organism which is injected.
What is an RNA vaccine?
RNA coding for an antigen is injected in a vesicle. Cells translate the RNA and trigger an immune response.
What is a subunit vaccine?
Antigen is extracted and injected. It may be attached to a protein.
What is an inactivated vaccine?
Killed pathogen is injected. Antigens are intact but there is no multiplication.
What is a Toxoid vaccine?
Toxins which are treated with formaldehyde. These trigger the production of antitoxins.
What it the genetic material in a HIV?
Two single strands of RNA.
What enzymes are found in a HIV?
One of these enzymes is reverse transcriptase, which allows the virus to convert RNA into DNA.
What is the capsid found in HIV made of?
A layer of protein molecules that surrounds and protects the genetic material.
What is the envelope found in HIV?
An outer later made up of phospholipids.
What are the glycoproteins found on the envelope for?
Also known as attachment proteins or envelope proteins, these help the virus to bind to host cells.
How do HIV cells replicate?
- Attachment proteins on the HIV attach to receptors on the helper T cells.
- HIV releases its RNA into the helper T cell.
- Reverse transcriptase converts this RNA into DNA.
- The viral DNA is injected into the helper T cells genome.
- The helper T cells DNA translated make viral proteins.
- The proteins are used to assemble new HIV particles.
- Fully assembles HIV particle leave the cell in order to infect other cells.
What is the first stage of infection of HIV?
Transmission - HIV is transmitted via direct contact with bodily fluids from an infected individual.
What is the second stage of HIV transmission?
Accuse infection - once HIV enters the body, it rapidly replicates. This causes flue-like symptoms for 2 to 4 weeks.
What is the third stage of HIV transmission?
Latency period - HIV replication drops to a low level for several years or decades. During this time, the individual usually experiences few or no symptoms. Antiretroviral therapy can prolong this stage for many years.
What is the fourth stage of HIV transmission?
AIDS development - after some years, HIV reactivates and destroyed helper T cells. As the number of T cells in the body drops over time, the immune system begins to fail. At this point, we classify the person as having AIDS.
How can HIV be treated?
Though it is currently incurable, antiretroviral therapy can reduce viral replication to such low levels that most infected individuals don’t experience any symptoms and can’t transmit the virus.
What are antibiotics?
Drugs that kill or inhibit the growth of bacteria. They target the bacterial enzymes and ribosomes used in metabolic reactions, meaning that do not damage human cells.
What are so ways that antibiotics can affect bacteria?
- Preventing the synthesis of bacterial cell walls.
- Disrupting proteins activity in the cell me membrane.
- Disrupting enzyme action.
- Preventing DNA synthesis.
- Preventing protein synthesis.
Why do antibiotic not work on viruses?
Antibiotics are unable to reach viruses as they invade the organisms own cells. This is due to the fact that viruses rely on host cells to Cary out metabolic reactions so antibiotics can’t disturb them to prevent replication.
What is antibiotic resistance?
Due to the increased use of antibiotics since the recovery of penicillin in the mid 20th centenary, antibiotic resistance had increases. This means that antibiotic that were once effective against bacteria no longer works, making it much more difficult to treat bacterial infections.
How does antibacterial resistance develop?
- Genetic mutations occur, making some bacteria resistant to an antibiotic.
- When an infection is treated with antibiotics, resistant bacteria are able to survive.
- Resistant bacteria reproduce, passing on the allele for the antibiotic resistant to their offspring.
How does the antibiotic resistant gene often get backed for one bacterium to another?
Conjugation - theses genes often occur in plasmids.
