specific response

Created by

Charlotte Waters

Cards (26)

how is the immune response activated
the presence of foreign antigens
what is an antigen
a molecule (usually glycoprotein) on the cell surface of a pathogen that triggers an immune response
what are the two types of phagocytes
neutrophils and macrophages
what happens in phagocytosis
phagocytes recognise non-self cells, engulf and digest them within a phagolysosome
describe the steps of phagocytosis
1. a phagocyte recognises the antigens on a pathogen
2. the plasma membrane and cytoplasm move around the pathogen, engulfing it and seal it in a phagosome. this may be made easier by opsonins which attach to the antigens to aid phagocytosis
3. a lysosome fuses with the phagosome to form a phagolysosome, the digestive enzymes which destroys the pathogen
4. if it's a macrophage, it will present the antigens on its surface to activate other immune system cells forming an APC
how do cytokines work
they are produced by phagocytes that have engulfed pathogens and act as cell signalling molecules, signalling to other phagocytes to move to the site of infection or inflammation
they can also increase body temp and stimulate the specific immune response
how do opsonins work
they attach to the cell receptors on the phagocyte and the antigen to help phagocytosis and make them more easily recognisable
how can you identify red blood cells on a blood smear? 
they are naturally stained red and don't have a nucleus
how can you identify neutrophils on a blood smear? 
multi-lobed nucleus and a grainy cytoplasm
how do you identify lymphocytes on a blood smear? 
much smaller than a neutrophil. The nucleus takes up most of the cell --> little cytoplasm to be seen + not grainy --> can't distinguish between T or B lymphocytes on a light microscope
how do you identify a macrophage on a blood smear? 
biggest white blood cell, and has a non-grainy cytoplasm
why does a neutrophil have a multi-lobed nucleus? 
flexibility --> can squeeze between other cells
which organelle do lymphocytes have in large numbers and why? 
mitochondria - for protein synthesis - to produce antibodies
what are T lymphocytes covered in
receptors
how does a T lymphocytes become activated + what is this called
the receptors on the surface bind to antigens presented by APCs --> clonal selection
what happens when a T lymphocyte become activated
clonal expansion: it divides to produce clones of itself:
T helper cells
T killer cells
T regulatory cells
T memory cells
function of T helper cells 
they release interleukins which bind to antibodies on B lymphocytes
function of T killer cells
they release perforins that attach to and kill cells that are infected with a virus
function of T regulatory cells
they suppress the immune response from other white blood cells, this stops immune system cells from mistakenly attacking the host's body cells
what are B lymphocytes covered in
antibodies
how do B lymphocytes become activated
when the antibody on the B cells surface meets a complementary antigen, it binds to it, this together with interleukins activates the B lymphocyte
what do B cells do
they bind to antigens to form an antigen-antibody complex and engulf the pathogen and processes it to become an APC
what happens once a B cell is activated
clonal expansion:
divides by mitosis to make B plasma cells and B memory cells
function of B plasma cells
secrete antibodies which bind to the antigens to form antibody-antigen complexes which can signal for the immune system to attack and destroy the pathogens
what is the primary response 
the relatively slow production of a small number of correct antibodies the first time a pathogen is encountered
what is an impact of the slow production of antibodies in the primary response 
the person will show symptoms until the body produces enough of the right antibody