IMMUNITY

Question	Answer
Name some parts of the body in which lymphocytes (white blood cells are found)	Blood, lymph and tissue fluid
What is the difference between specific and non specific defence mechanisms?	Non specific - don't distinguish between pathogens; respond to them all in the same way; response is immediate. Specific - distinguishes between different pathogens; takes longer but provides long lasting immunity
Name some examples of physical barriers?	Skin, mucus linings, HCl in stomach
How are phagocytes attracted towards the pathogen in phagocytosis?	Chemical products of the pathogen act as attractants
What happens after the pathogen is attached to the phagocyte?	The phagocyte ingulfs it
What is the name of the vesicle in which the pathogen is engulfed in?	A phagosome
Which structures inside the phagocyte bind to the phagosome and release their contents?	Lysosomes
What is in the contents of the lysosomes and what do they do?	Enzymes - break down the pathogen by hydrolysis
What happens to the soluble products from the breakdown of the pathogen?	They are absorbed into the cytoplasm of the phagocyte
Phagocytosis causes ___________ at the site of infection	Inflammation
What are the two specific defence mechanisms?	Cell mediated response, humoral response
Which lymphocytes are involved in humoral immunity?	B lymphocytes
What do T cells respond to?	An organisms own cells that have been invaded by non-self material
What is a pathogen?	A microorganism that causes disease
How can T cells distinguish between invader cells and normal cells?	Phagocytes present antigens of pathogen on their own surface, virally invaded body cells present viral antigens on their cell surface membranes, cancer cells present antigens as a sign of distress
What name is given to these types of cell?	Antigen presenting cells
What helper T cells do to the antigens on the surface of the phagocyte?	Fit onto them
What does this activate?	Other T cells to divide rapidly and form clones
What are the 4 things the cloned cells can do?	1. Develop into memory cells 2. Stimulate phagocytosis 3. Stimulate B cells to divide 4. Kill infected cells
Which part of the T helper cells fit on to the antigen?	The specific receptor
What do killer T cells produce and how does it kill infected cells?	A protein - makes holes in the cell surface membrane; cell becomes freely permeable and dies as a result
Where do T lymphocytes mature?	The thymus gland
Where do B lymphocytes mature?	Bone marrow
What do B cells produce?	Antibodies
What happens when a specific antibody attaches to an antigen in the blood?	The type of B cell that produces it divides rapidly by mitosis
In practice, most pathogens have different proteins on their surface, what do these act as?	Antigens
Give an example of a pathogen that releases a toxin	The pathogen that causes cholera - vibrio cholerae
What do antibodies do?	Destroy the pathogen and any toxins it produces
What do the plasma cells do?	Produce antibodies to destroy the pathogen
Why do people get flu more than once?	There are many different strains - the antigens of the virus are constantly changing (antigenic variability)
How many polypeptide chains are antibodies made of?	4 (2 heavy chains and 2 light chains)
When the antibody fits onto the antigen, what name is given to this structure?	The antigen-antibody complex
Name the regions of an antibody	Variable region Constant region
How can monoclonal antibodies be used in cancer treatment?	They can attach to the cancer cells and activate a cytotoxic drug which kills the cancer cells
Why does this cause little, if any damage to other cells?	The cytotoxic drug is only activated by cells to which the monoclonal antibodies are attached i.e the cancer cells
Monoclonal antibodies can 'knock out' specific T cells - what is this useful for and why?	Transplant surgery - there is often rejection due to the action of T cells
What were the 2 main struggles with trying to produce monoclonal antibodies?	B cells are short lived and only divide inside a living organism (have to use mice)
Why are they called 'monoclonal' antibodies?	Because they come from a single B cell
What is the name given to the process in which the antibodies are modified so that they work in a human? Why is this necessary?	Humanisation Monoclonal antibodies from a mouse will be recognised as 'non-self' and destroyed by human antibodies
What is active immunity?	When an individual is exposed to a pathogen and becomes immune by producing their own antibodies in response.
What is passive immunity?	Immunity by the introduction of the antibodies from an outside source - can be induced by a vaccine
What are 4 features of a successful vaccination programme?	Few side effects - must be sufficient quantities to immunise the entire vulnerable population - must be means of producing, transporting an storing the vaccine available - trained staff
A vaccination might not eliminate a disease. Why?	People may have defective immune systems - antigenic variability - objections to vaccination - people may harbour the pathogen and infect others - some pathogens 'hide' from immune defences
Tuberculosis is another disease that is difficult to control by vaccination. There are 4 reasons why. What are these reasons?	Increase HIV = increase in defective immune systems; increase elderly population = increase in defective immune systems; many people in overcrowded accommodation; mobile populations
IMMUNITY (1.7)

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