6 Immunity Flashcards
Role of the skin as a barrier.
Physical
-waxy and waterproof due to keratin
Role of stomach acid as a barrier.
Chemical
- low pH which kills bacteria
- Hydrochloric acid
Role of gut flora.
Helps exclude bad bacteria
Role of skin flora.
Takes up space outcompete pathogen
What are the three features of an inflammatory response?
Swelling, pus, redness
Describe the process of an inflammatory response.
- foreign antigen recognised
- mast cells release histamine
- histamine increases blood flow
- capillaries dilate no become leaky
- platelets promote clotting and stop pathogens spreading
- dead/used wbc make pus
Describe the process of phagocytosis (REPLEE)
Recognise- foreign pathogen recognised from its antigen
Engulf- pathogen engulfed by endocytosis
Phagosome- invagination of plasma membrane= phagosome formed
Lysosome- phagosome+ lysosome fuse = phagolysosome
Enzymes- hydrolytic enzymes (lysoSYME and protease) digest pathogen
Exocytosis- remove harmless product
Describe interferon action. (virus only)
- virus invades cell= cell releases interferons (proteins)
- interferons diffuse from cell
- binds to nearby receptors on outsides of cells
- stimulates a pathway to inhibit protein synthesis and stop viral replication
also promotes inflamation
What is the goal of interferon action in short.
prevent viral replication by signalling (inteferons presented on outside of cells)
what is a lysosome?
membrane-bound sac containing hydrolytic enzymes
name two hydrolytic enzymes:
lysosYme and protease
what are antigens?
molecules on the surface of cells that can bind to specific antibodies
what are antibodies?
Y shaped proteins that recognise and bind antigens
what type of proteins are antibodies?produced by?
glycolic-proteins made by WBCs
describe the structure of an antibody.
- 4 polypeptide chains, 2 light on outside and heavy on the inside
- variable portion on tips rest is constant
what makes antibodies specific?
the variable portion allows flexibility to certain antigens
how are antibodies produced?
secreted by plasma cells and cloned once right shape is identified
describe the role of antibodies.
- bind to antigens on bacterias surface-labelling it as foreign
- antibodies clump together due to Y shape (agglutination)
- antibody binds to antibody receptor on macrophages
- macrophage now easily engulfs all bacteria
3 ways antibodies help clear infections: NAP
Neutralising toxins- bind to prevent effect
Agglutinating pathogens- 2 binding sites on each (Y)
Preventing pathogens from binding to cells
Role of B-Memory cells is …
to remember previous pathogens for a fast immune response in the future
Role of B-effector cells is …
to differentiate in plasma cells which produce the specific antibody
Role of T-helper cells is …
t helper clones release cytokines to activate clonal selection of B cells before they differentiate
Role of T-Memory cells is …
to create a faster stronger response to previous pathogens
Role of T-killer cells is …
- to bind to cells making them APCs
- active t killer cells bind to APCs creating pores to allow water and ions to move in via osmosis to cause LYSIS, pathogens release are phagocytosed
what are APCs?
antigen presenting cells digest pathogens, signalling to other cells an immune response
how can different types of antibodies come about?
alternative splicing
-exons are rearranged to a new sequence to make new combinations therefore new proteins form
what is MHC II?
major histocompatibility complex II are genes found on the surface of APCs (only) that will code for cell surface membrane proteins that will PRESENT A SMALL PART OF THE FOREIGN ANTIGEN to help distinguish between foreign and own cells
what is MHC I?
found on all body cells
how can you develop natural active immunity?eg.
-body makes antibodies through immune response after being expose to a pathogen
eg colds
how can you develop artificial active immunity?eg.
- exposed to antigen by injection into the body so body then reacts with an immune reponse
eg. vaccinations
how can you develop natural passive immunity?eg.
-woman who is ill passes antibodies to child via umbilical cord while in womb or via milk after
how can you develop artificial passive immunity?eg.
-injected with antibodies, body cannot produce them
explain how vaccines can give you immunity.
-imitate infection
by being exposed to either a dead pathogen or weakened version o fit our body should recognise its antigens as foreign and begin an immune response to develop antibodies and memory cells to create a fast recovery if ver infected.
why are weakened pathogens better than dead ones for vaccines?
- more closely resemble real infection
- Immunity is longer lasting
what are the dangers of vaccines? main issue?
- side effects
- larger impact on immune system than intended, infection from other pathogens is more succeptable
- vaccines target specific proteins so if pathogen mutates and antigens change then they are no longer useful
