immunity Flashcards
ingesting of a pathogen by phagocyte
phagocyte attracted to pathogen via chemoattractions
phagocyte recognises foreign antigens on pathogen
cytoplasm of phagocyte engulfs pathogen forming a phagosome
lysosomes fuse with phagosome and release lytic enzymes to break down pathogen
phagocyte becomes apc so t lymphocytes know the invasion
antigen
protein molecule that triggers an immune response
lymphocyte
white blood cell
antibody
produced by lymphocytes
t vs b cells
t give cell mediated immunity,made in bone marrow mature in thymus
b cell gives humoural immunity, made and mature in thymus
cell mediated immunity
t helper cells have cd4 receptors which fit onto antigens on apc
t helper cells release interluekins to alert other cells
activated t cells multiply via mitosis producing lots of cloned cells which differentiate
cell mediated immunity pt2
what to cloned t cells differentiate into
t memory cells to remember the antigen and remain in lymph nodes to respond if attacked again
cytotoxic t cells release perforin to kill pathogens
interelukins which stimulate b cells to divide in plasma cells to make antibodies
stimulate phagocytes to do more phagocytsis
humoural immunity
b cells with antibodies
when an antibody binds to complementary shaped antigen on pathogen they divide into plasma cells
clonal selection pt 2 of humoural immunity
b cell binds to complementary antigen
b cell engulfs pathogen and becomes a apbc
what to apbc divide into
b plasma which secrete specific antibodies that combine with antigenic pathogens to form a-a complex which stimulates phagocytosis ad destroys pathogen
b memory cells which remain in body and can divide into plasma if invaded
primary response
when invaded first time, not many plasma cells that make the specific antibody for that antigen
eventually theres enough to secrete enough antibodies
but in that time pathogen has destroyed cells and released toxins so you get ill
but you now have memory cells for that specific antigen so next time response is fast
secondary response
clonal selection is faster. memory b cells divide into plasma cells for antibodies
memory t cells divide into cytoxic t cells
faster and greater rate
u dont get ill
antibodies how made and what are they
by plasma b cells specific and complementary to antigen 2 antigen binding sites to increase chances of binding to two diff antigens on 2 diff pathogens 4 polypeptide chains hinge region
antibody reactions
stimulate phagocytes
agglutination- antibodies bind to more than 1 antigen at once forming a lattice structure, immobilising the pathogen and allowing phagocytes to engulf easier.
precipitation- precipitates toxins to render them harmless
vaccine
contains dead or inactive pathogen or just antigens
cause body to produce memory cells
herd immunity
lots of people are vaccinated so those that arent less likely to get it
active immunity
make your own antibodies
natural- after being ill
artifical- after vaccine
passive immunity
from another organism
natural-breastfeeding
passive - antivenom
no memory cells made
hiv
uses t helper cells as host cells , so without these no b cells phagocytes cytotoxic t cells and immune system fails and get aids
hiv replication
attatchment protein binds to receptors on t helper cells
capsid released into cells where it releases its genetic info rna
reverse transcriptase makes a complementary strand of dna from viruses rna template
double strand made
host cell enzymes make proteins for virus
why dont antibiotics work on viruses
antibiotics kill bacteria by killing its ribosomes
viruses dont have their own
antiretrioviral drugs stop reverse transcirptase and as humans dont have it we safe
