Immunology Flashcards
What is a pathogen?
A pathogen is a bacterium, virus or other organism that can cause disease.
What are epithelial cells?
Epithelial cells form a physical barrier. Closely packed epithelial cells are found in the skin and inner linings of the digestive and respiratory system.
What is the inflammatory response?
The inflammatory response is a defence mechanism triggered by damage to living tissue.
What is histamine?
Histamine is released by mast cells, causing vasodilation and increased capillary permeability. The increased blood flow leads to an accumulation of phagocytes and clotting elements at the site of infection.
What are phagocytes?
Phagocytes recognise pathogens and destroy them by phagocytosis. They also release cytokines.
What is phagocytosis?
Phagocytosis involves the engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes.
What are cytokines?
Cytokines are protein molecules that act as a signal to specific white blood cells, causing them to accumulate at the site of infection.
What are lymphocytes?
Lymphocytes are the white blood cells that are involved in the specific immune response. They respond to specific antigens on invading pathogens.
What are antigens?
Antigens are molecules, often proteins, located on the surface of cells that trigger a specific immune response.
What are the two types of lymphocytes?
B- lymphocytes and T- lymphocytes.
What are B-cells?
B-cells produce antibodies against antigens and this leads to the destruction of the pathogen.
What are T-cells?
T-cells destroy infected body cells by recognising antigens of the pathogen on the cell membrane and inducing apoptosis.
What are antibodies?
Antibodies are Y-shaped proteins that have receptor binding sites which are specific to a particular antigen on a pathogen. They become bound to antigens, inactivating the pathogen.
What happens to the antigen-antibody complex?
It is destroyed by phagocytosis.
What is an allergic reaction?
An allergic reaction is a hypersensitive response that comes around when B-cells respond to substance that are harmless to the body. (Pollen)
What is apoptosis?
Apoptosis is programmed cell death.
What happens to a cell once apoptosis has happened?
It is removed by phagocytosis.
What happens when T-cells fail to distinguish between self-antigens and non-self antigens?
Autoimmune disease.
What are memory cells?
Cloned B and T cells that survive long term.
What happens in a secondary response?
Antibody production is greater and more rapid then during the primary response.
What is HIV?
HIV attacks and destroys T-cells. HIV causes the depletion of T-cells, which leads to AIDS.
What happens to individuals with AIDS?
Individuals with AIDS have a weakened immune system and so are more vulnerable to opportunistic infections (pneumonia).
How can immunity be developed?
By vaccination using antigens form infectious pathogens, so creating memory cells.
What is an adjuvant?
An adjuvant is a substance which makes the vaccine more effective, so enhancing the immune response.
What is herd immunity?
Herd immunity occurs when a large percentage of a population is immunised. Non-immune individuals are protected as there is lower probability they will come into contact with infected individuals.
What does the herd immunity threshold depend on?
- the type of disease
- the effectiveness of the vaccine
- the density of the population
What are mass vaccine programmes designed for?
To establish herd immunity.
What difficulties arise from widespread vaccination?
- poverty in the developing world
- when vaccines are rejected by a % of the population in the developed world.
What is antigenic variation?
Antigenic variation occurs in the influenza virus explains why it remains a major health problem and why individuals are required ti be vaccinated every year.
What does the design of clinical trails to test vaccines and drugs involve?
- randomised trails
- double- blind trials
- placebo- controlled trials
What is immunity?
Immunity is the ability of the human body to resist pathogens, some toxins and cancer cells through the immune system.
What are mast cells?
Mast cells are types of white blood cells which release histamine and various cytokines when skin is injured.
What is a self antigen?
A self antigen is found on the bodies own cells and is recognised as belonging to ‘self’
What is a non-self antigen?
A non-self antigen belongs to invading bacteria , transfused cells and trigger an immune response.
What is so special about the membrane receptor on a lymphocyte?
It is specific for one antigen.
What happens once an antigen binds to a lymphocyte?
Antigen binding leads to repeated lymphocyte division, resulting in the formation of a clonal population of identical lymphocytes.
How can immunity be developed?
By vaccination using antigens from infectious pathogens, so creating memory cells.
What is different about the antigens used in a vaccine to one found on a pathogen?
It has either inactivated,dead part of it or weakend.
What is an adjuvant?
An adjuvant is a substance which makes the vaccine more effective, so enhancing the immune response.
What substance is commonly used as an adjuvant?
Aluminium salts.
What is herd immunity?
Herd immunity occurs when a large percentage of the population is immunised. Non-immune individuals are then protected as there is a lower probability they will come into contact with infected individuals.
What does the herd immunity threshold depend on?
- type of disease
- the effectiveness of the vaccine
- the density of the population
What are mass vaccination programmes designed to establish?
Herd immunity
What difficulties can arise with widespread vaccination?
Due to poverty in the developing world or when the vaccines are rejected by a percentage of the population in the developed world.
When are memory cells ineffective?
When the antigens change shape.
What is antigenic variation?
Antigenic variation is when the antigens on a pathogen change shape causing memory cells not to work.
What is a clinical trial?
A clinical trial is a research study to evaluate the effectiveness of drugs or vaccines by monitoring their affects on a large group of people.
What three parts are part of a clinical trial?
Randomised trials, double-blind trials and placebo controlled trials.
What is meant by randomised trial?
Subjects in clinical trials are divided into groups in a randomised way to reduce bias in the distribution of characteristics within a group.
What is meant by a double-blind trial?
In a double-blind trial neither the subjects nor the doctor know which group subjects are in to prevent bias.
What is meant by placebo controlled trial?
One group of subjects receives the vaccine or drug well the second group received a placebo control to ensure valid comparisons.
In a clinical trial should the group sizes be small or large and why?
Group sizes should be large to reduce experimental experimental error and established statistical significance.
