6.3 Flashcards
when does immune responce take over
when pathogens overcome the defence system of the body
steps of an immune responce
- detection and identification of foreighn substance
- communication with other immune cells
- recruitment of help and co-ordination of the response
- destruction or suppression of the invader
How does immune system comunicate
chemical signals
what do antibodies do in the immune respoce
bind to antigen as a signal
what do cytokines do in the immune responce
affect growth or activity of other cells
what are teh two main catogories f immunity and talk about thier responce time
innate and adaptive immunity that overlap and cooperate in mounting responses to pahtogens
- responce time is diffeerent for inate and adaptive immunity
- inate is a more rapid, less specific responce - can lead to adaptive responces
adaptive responce is slower and, more specific
innate imunity
when present and what it encounters
responce tie and memory
wha it attack
inflamation
what organisms have this
present before pathogen is encountered and is non-specific
response begins within minutes to hours, and it does not remember past infections
some non-specific cell types and proteins
inflamation is distinctive in innate immune response
all organisms have this
adaptive immunity
what it directed to
when it develops and how long it take
memory
devided into:
what foud in
directed at specific invaders
develops after the pathogen is encounered and the response takes days to weeks
remembers past infections
devided into:
1. cell-mediated immunity
2. antibody-mediated immunity (humoral imunity)
only found in vertebrates
1st line and 2nd line of defence
1st ine includes physical bariers and chemical bariers, these are the most volnerable because the epithelium is thin and exposed to outside environment
second line of defence are patrolling or stationary leukocytes and blood protiens. these react the same way to every infection
what are majority of innate immune system cells and how do hey atttract other cells
phagocytes are majority and which destroy or supress the inveder by ingesting it
attract other cells by secreting cytokines - chemicals that attract other immune cells are called chemotaxins
types of chemotaxins
cytokines (chemokines) and other immune blood protiens
products of tissue injury
bacterial products
phagocytes movement, and how they identify the invader and engulph it
leave the circulation and enter tissue through capillary walls - extravasion
identify the invader by using chemical cues which interaccts with receptors on the phagocyte membrane
many receptors bind sequentially to allow the phagocytes to engulf the invader. movement of the psuedopodia is aided by actin filaments to push the cell around the invader
what about the pathogens that do not have surface featurs that cen be recognised directly by phagocytes
- blood proiens bind to and coat the pathogen to “tag” it
- phagoctes have receptors for these blood protiens
- tagging a pathogen is called opsonization
a protie that can fo it is an opsonin
- once ingested, the partical is in a vesicle called a phagosome
- these fuse with lysosomes which conain digestive enzymes and chemicals that kill the pathogen - forms a phagolysosome
- dead phagocytes, tissue fluids and debris collect at the site of injury as pus
- those phagocytes that aare also APCs present antigens from digested bacteria on the surface of the APC via class II MHC
natural killer cells
time, receptors
what they do
natural killer cells are lymphocytes associated with innate immunity; however lymphocytes are generally associated with adaptive responses
NK cells act within minutes, and they do not have specific receptors as seen in B cellsand T cells
they bring about apoptosis in pathogen-infected cells
can also attack tumour cells
produce important cytokines sch as interfoerons - interfere with viral replication
IFN a and B
IFN Y
induce an “antiviral state” in nearby cells that prevents viral replication
activates macrophages and other immune cells
