Pack 10 disease and immunity

What is an antigen

a foreign non self protein that stimulates an immune response

2 ways pathogens can cause disease

Release toxins, damage cells

name the white blood cells and the type of immune response they are involved in

phagocytes-involed in non-specific response form along with platlets which are involved in clotting, lymphocytes-specific response such as B and T cells, Plasma-specific response that transports components around the body

what do lysosomes contain and what is their function

hydrolic enzymes (lysozyme) which hydrolise cells and organelles

describe the non specific immune response /phagocytosis (5 marks)

phagocyte recognises and binds to the pathogen, phagocyte engulfs pathogen, they are enclosed in vesicles, lysosomes fuse with the vesicle, lysosomes contain hydrolic enzymes which damage bacterial cell wall, these hydrolise the pathogen

describe the cellular response

A specific Th cell binds to an antigen on antigen presenting cell, this activates Th cell to divite by mitosis, to produce more Th cells and memory cells, Th cells release cytokines which stimulate cytotoxic t cells to divide by mitosis

Describe the hummoural response

receptors on specific b cell bind to an antigen, they are activated by cytokines to divide by mitosis, producing plasma cells and memory cells, plasma cells produce and release antibodies, memory cells remain to divide and prpoduce more antibodies more rapidly following second exposure to same antigen

what is an antigen presenting cell

cells infected by virus such as a phagocyte which has just engulfed a pahtogen or an abnormal cell which has become cancerous

explain why secondary response is more rapid than primary response

it takes time for specific B lymphocytes to be activated which has to undergo mitosis to produce plasma, memory b cells and antibodes in primary response whereas in secondary response there are already memory cells against the ag which can divide more quickly in mitosis and produce larger numbers of antibodes quicker.

outline 3 differences between the cellular and hmoural response

cellular: no antibodies,act on damaged or infected cells, t cells involed. Humoural:antibodies made, act on pathogens, b cells involved

describe antigenic variability (2 marks)

when the antigens on the surface of each strain are different so will not correspond to memory cells from previous infections

How does HIV replicate

attachment proteins bind to specific complimentary receptors on surface of Th cells, the capsid(containing genetic material) and reverse transcriptase are released, RT us released used to make a complimentary strand of DNA using the viral RNA as a template. from this, double stranded DNA is made which is incorporated into the Th cells own DNA and used to make new viral proteins. These new HIV viruses bud from cell and destroy them and other cells