INNATE IS Flashcards
what is the immune system
a collection of cells, tissues and molecules that mediate resistance to infections and elimiates tumours
functions of the immune system (IS)
- prevent infections
- eradicate established infections
- detect and eliminate tumours
site of immune system
EVERYWHERE,
immune cells can move around
molecules produced by the immune cells can also move around
work on all sorts of other systems
anatomy of the immune system
physical / chemical barriers :
- epithelial cells of skin, gut and respiratory tract
- secretions llike sweat/wax/tears
- mucus in the nose, trachea, gut
- urine
etc etc
Cells and molcules travel through 1) blood and 2) lymphatic vessels to go to the organ systems
Central sites
Peripheral sites
what is the central site of the immune system
also know as(lymphoid tissues or lymphoid organs)
- where the immune cells are produced etc
Primary lymphoid organs
1) bone marrow = makes all blood cells including lymphocytes. e.g B cells are a type of lymphocyte which can produce antibodies and stay in the bone marrow until fully matured and gets released into the blood stream
2) thymus = maturation of T cells, another form of lymphocytes.
–> are developed in the bone marrow but move to the thymus glands to mature
Secondary lymphoid organs
1) spleen= filters blood and removes old/damaged RBCs
2) lymph nodes = filters, trapping and destroying foreign substances and pathogens that have entered the body
3) mucosa-associated lymphoid tissue (MALT) = protects mucosal surfaces of the body like the linings in the digestive, respiratory, urogential systems.
what are the peripheral sites
all th other tissues and systems e.g skin, liver, gut, heart, brain, CNS, muscles, lungs etc
they contain all kinds of immune cells that can detect and respond pathogens that may have entered the body
innate immune system cells
hematopoietic stem cells (HSC)s are stem cells found in the bone marrow that can differientiate
It can differentiate to form a cell called the common myeloid progenitor
the common myeloid progenitors can then further get neutrophil, basophil, eosinophil, monocyte cells = ALL CELLS IN INNATE IMMUNE SYSTEM
features of the innate immune system
1) speed
-early/rapid
2) duration : short
3) repetitive : responds exactly the same way a microbe is encountered
4) interactive with other cells in innate and adaptive IS
5) non-reactive to the host : only responds to foreign substances
how does IS tell the difference between own and other stuff
one way : receptors, these receptors are specific to different microbes,
own cells don’t look like it
components of the innate IS
1) epithlial barries
2) cells
- phagocytes (neutrophils & macrophages)
== ingest and engulf these microbes
- exocytes (eosinophils, mast cells, basophils)
== releases active mediators i.e enzymes, hormones, signalling molecuels as a response
3) molecules
- cytokines
-blood proteins
mast cells
found in peripheral tissues that are exposed to the environemt e.g skin, lung, gut
have recpetors to sense the danger (first line of defence of the cells to danger)
when triggered by like allergens or pathogens = releases its active mediators including histamine, cytokines and proteases
–> increases vascular permeability & promotes inflammation)
cytokines??? functions
proteins that can be produced/secreted by other cell tyles e,g immune cells
FUNCTIONS:
1) main mediator for comminication between cells = acts as messengers
2) can regulate (promote or reduce) inflammatory/ activate T and B to stimulate immune reactions
3) can target cells in 3 ways
a. autocrine : cells releases cytokines and it attaches to own receptors to trigger a respsinse
b) paracrine : a cell releases cytokine to attach to an adjacent cell to trigger a response
c) endocrine : the cytokine travels very far to a very very distant cell
mast cell mechanism
they are first responders
when danger is detected:
releases granules ( contains histamine and inflammatory cytokines)
–> allows the blood vessels to dilate, more permeable, blood can leak out and the mediators can cause the redness and inflammation
monocytes and neutrophils can also come out, exiting the blood vessels and entering the tissue
neutrophils can also trap pathogens and bacteria etc to prevent it from entering the body
monocytes become macrophages to eat the foreign substances up by phagocytosis
how do the cells know where to go
chemokines make that possible
cells follow the scent of the chemokines
cells have different receptors that attach to specific chemokines so they go to where they need to go
so specific foreign substances can stimulate chemokines, so our e.g neutrophils can follow it and be attracted to it, and eventually engulf it. it has a specifc smell/pattern that our own cells don’t release so our phagocytes will ignore :)
rolling, adhesion, extravasate and migration
inflammation area releases cytokines
cytokines bind to endothelial cells of the blood vessels which causes the cells to express selectin (surface protein)
selectin is attrached to the carbs in the leukocytes within the blood vessesls but they have a low affinity so the leukocytes ROLL
they roll across these selectins expressed until they find a small gap between the endothelial cells and then they ADHERE
from there, they squeeze out and EXTRAVASCATE (leak out of the blood vessels) into the adjacent connective tissues
they can then MIGRATE to the inflamed area by following the chemokines and perform phagocytosis
