Immunology Flashcards
What is the First line of defence?
Innate/non-specific.
• Consists of skins & mucous membranes - physical barriers.
• Aims to prevents organisms entering the body.
What is the Second line of defence?
Innate/non-specific.
• Initiated if pathogens penetrate the first line.
• Includes inflammation, fever, antimicrobials & phagocytes + NK cells.
What is Inflammation?
Damage to the bodies tissue triggers a defensive mechanism known as inflammation.
Functions to prevent the spread of microbes, clear cellular debris & repair damaged tissue.
What are the THREE steps to Inflammation?
1- Vasodilation & increased blood vessel permeability.
2- Phagocyte migration to the damaged area.
3- Tissue repair.
What are some common signs of Inflammation?
Heat, redness, swelling, pain, pus.
What are the Phagocytes present in Inflammation?
Neutrophils,
Monocytes,
Natural killer cells.
What is Fever?
A internal body temperature above 37.8°C.
Pyrogens trigger the hypothalamus to increase temperature. Pyrogens are released by phagocytosis.
What is the function of Fever?
High temperatures slow bacterial growth, increases the rate of chemical reactions and induce the feeling of tiredness in the individual to ensure rest.
What are Antimicrobial substances?
Substances which are released when the first line is penetrated. Four substances work to enhance the response of the second line.
What are the FOUR antimicrobial substances?
Interferons,
complement proteins,
iron-binding protein, antimicrobial protein.
What is the function of Interferons?
enhance phagocytes & NK cells, suppress tumor formation and secrete proteins to inhibit virus replication.
What is the function of Complement proteins?
Enhance inflammation, phagocytosis & help with antibody immunity.
What is the function of Iron-binding proteins?
Transferrin: removes iron from circulation to inhibit bacterial growth.
What is the function of Antimicrobial proteins?
Kill a wide range of microbes.
What is the Third line of defence?
Adaptive, (specific) immunity.
Once the first and second line are penetrated, the third line produces an adaptive response to the invader.
What is Immunity?
The capacity of the immune systems to successfully defend the body against potentially infectious agents.
Which cells are vital in adaptive immunity?
Lymphocytes, particularly T & B lymphocytes.
Where do the Lymphocytes originate?
Stem-cells in bone marrow.
Where do T & B lymphocytes complete development?
B cells complete development in the Bone marrow.
T cells complete development in the Thymus.
What occurs to T & B cells after developing?
They are equipped with hundreds of thousands of receptor molecules on their surface which recognise a specific foreign molecule (antigens).
What is an Antigen?
any substance that the body recognises as foreign or non-self.
• Often components of the surface of microbes.
What is Antibody mediated immunity?
A response which activates B cells to proliferate and produce:
•Plasma cells, which make antibodies.
•Memory cells, which persist in the body and can recognise the same antigen if it re enters.
What is Antibody tire?
The concentration of an antibody in a persons serum (blood)
What is the Primary response?
The response of the immune system the FIRST time it encounters a particular antigen.
• Has a ‘lag’ period of 5-7 days as B cells proliferate and plasma cells form.
What is the Secondary response?
Occurs when increased numbers of specific memory cells are stimulated to produce more plasma cells.
• Reaction occurs rapidly.
What are Antibodies?
Y shaped, globular protein molecules.
• also known as immunoglobulins.
• found in blood, lymph, CSF, urine.
What are the different types of antibody?
IgG, IgA, IgM, IgE.
What is IgG?
Comprises about 80% of all antibodies in serum.
• Protect from bacteria, neutralise toxin & viruses, trigger complement proteins.
• Can cross the placenta.
• Longest lasting.
What is IgA?
Comprises about 10-15% of antibodies.
• Most common antibody in secretions & on mucous membranes: mucus, saliva, tears, breast milk.
• Binds to antigens before they invade tissue & prevent adhesion to mucous membranes.
What is IgM?
Comprise about 5-10%.
•First to be produced when antigen is detected.
•Short lasting
•Clump antigen & trigger complement proteins.
What is IgE?
Only present in tiny amounts,
•Binds to mast cells & basophils which release histamine when antigen binds to IgE.
•Major defence in parasite infection.
•Involved in allergic reactions.
What are the main functions of Antibodies?
•Enhance phagocytes: coat the microbes making them easier to detect and ingest.
•Activates complement: antibody binds to antigen and exposes an area for complement proteins to bind.
•Neutralisation: antibodies bind to & block attachment site of microbes.
•Agglutination: clumps microbes into larger complexes so phagocytes can consume them together.
What is Cell mediated immunity?
T cells destroy cells which harbour bacteria, virus, cancer & parasites.
•An infected cell displays microbial antigen fragments on its surface.
• T cells bind to & insert perforin proteins into the cells.
•Perforin allows enzymes to enter the cell and kill it.
Stops virus multiplication & exposes it to antibodies.
•Memory T cells are produced.
How does the body know which cells are its own?
Major-histocompatibility complex (MHC proteins)
•Proteins on the surface of our cells identify them as self. they are unique to each individual and all cells expect RBC have them.
•An alternative form of MHC protein is produced by phagocytes after contact with a foreign cell- results in B&T cells specific to that pathogen.
