Immune system Flashcards
3 components of the immune system
lymphoid tissue
chemical signals
immune cells
pathologies ( cause or effect of a disease)
- incorrect respsonse–> autoimmune
- overactive imune response- allergies
- lack of immune response- immunodefiicency
is sebum, swear urine and gastric juice chemical or physical barriers?
chemical
3 types of lymphocytes
B cells, T cells, NK
NK are apart of innate or adaptive immunity?
innate
components of innate
complement proteins, NK, phagocytes
primary lymphoid tissues
thymus and bone marrow
what is thymus’s role in immunity?
It is a endocrine gland responsible for the maturation of T cells by release of peptide hormones: thymosin, thymopoietin and thymulin
what is special/unique about the thymus?
it is larger in children, then shrinks in adulthood
- during development cells that would be self-reactive are eliminated, and replaced with fat
secondary lymphoid tissues (encapsulated)
spleen
lymph nodes
diffuse lymphoid tissue
lymphoid nodules
- loose connective tissue with densely packed lymphocytes (B,T cell and NK)
- no fibrous capsule
- found beneath epithelial lining of organs that have direct contact with outside world ( need lots of protection) such as urinary tract, responsible, digestive tract
what is lymph contain? how does it differ from blood?
- clear white fluid. no RBC. has proteins, salts, glucose, WBC
- comes from interstitial fluid
how is lymph picked up ?
leaky blood capillaries, fluid leaks out becoming interstitial fluid, lower pressure in lymph capillaries so leaks into there
how much lymph flows per day?
3.6 L
what forces fluid out of capillary?
a great capillary hydrostatic pressure than blood osmotic pressure
what allows for reabsorption of fluid into blood cap?
a great blood osmotic pressure than CHP
what are interferons
chemical released from infected cell to warn nearby cells
what is the function of the spleen in immunity?
filter for blood as lymphoid tissue
- red blood cell clearance
what class of formed elements mediate immunity in blood
WBC/leukocytes
basophils and mast cells
release chemicals for inflammation and allergy response (ex. histamine and heparin)
Neutrophils
ingest and destroy invaders
- first responder
- most abundant
- phagocytes
Eosinophils
1-3%
- destroy antibody coated parasites
- protect against bacteria and parasites mainly
APC
macrophages, B cells, dendritic cells
NK cells
release lytic granules that kill some virus-infected cells
- induce apotheosis
- attack tumor cells
- secrete interferons
in order to phagocytos a pathogen with a capsule it must?
have antibody molecules on it, in order for phagocyte to recognize it
where are immature dendritic cells found
peripheral tissues, migrate in lymph vessels to lymph nodes and mature ones present their antigen to naive T cells
interferon alpha nd beta do what
prevent viral replication
interferon gamma does what
activates macrophages and other immune cells
steps in inflammation
cytokines released
triggers acute phase proteins to be made in liver and histamine release from mast cells
- histamine casques vasodilation and caps to become more permeable
chemotaxins
attract phagocytes to site of. infection
opsonins
coat pathogens
pyrogens
fever-producing substances
acquired immunity
responses to and targets a specific foreign molecule called an antigen
80% of circulating lymphocytes are
T cells
types of T cells
cytotoxic
helper
suppressor- keep immune system from becoming over active
memory
10-15% of circulating lymphocytes are
B cells
NK
5-10% circulating lymphocytes
- immunological surveillance
- attack foreign cells
- part of innate immunity
lymphoid stem cells in bone marrow give rise to
NK, B cells
- the lymphoid stem cell travels to thymus to mature with thyme hormones
Naive lymphocytes have not yet been …
stimulated by antigen
- once stimulated= clonal expansion
what happens during clonal expansion
Naive lymphocyte gets stimulated–> rapidly replicates–> some turning into effector cells ( plasma, helper, cytotoxic T cells) some become memory cells
Humoral immunity (B cells)
called this because “humour” = body fluid and it involves substances found in the humors –> antibody related
- clonal expansion of B cells rest in plasma cells which each produce a specific antigen binding protein called an antibody
antibodies are known was
gamma globulins
how do the five classes of antigens vary
Fc region
what is the most common antibody
IgG
which one is involved in allergic response
IgE
which one for primary response
IgM
which one secretory form / plays role in mucus membranes
IgA
function of antibodies
- antigen binds to antibody
- activates B lymphocyte which causes it to divid into plasma and memory cells
- more antibodies secreted - act as opsonins- tagging antigens for phagocytosis and antigen clumping and inactivates antigen
- activates antibody dependant activity
- triggers mast cell to release granules
- activates complement
adaptive response is broken in two parts
humeral response and cellular response
cell-mediated response
T helper cells gets activated by APC
- releases cytokines to activate naive cytoxic T cell to turn into active cytotoxic T cells
- or infected cel can trggernaive cytotoxic T cell to become activated through MHC antigen complexes
T lymphocytes recognize antigens with ?
- use contact dependant signalling
MHC proteins
( which are found on all body cells and vary from one person to the next )
how cytotoxic T lymphocytes are activated?
a cell with MHC antigen binds to T lymphocytes
- can kill it
how do helper T cells become activated
bind to MHC-II APC and then secrete cytokine to activate other immune cells
MHC 1
found on all nucleotide cells of the body
- recognized by NK and cytotoxic T cells
MHC 11
found only on APC
- recognized by helper T cells
importance of MHC
mark themselves as “self”
- so immune system will not attack
can T cells detect antigen in blood, fluid and lymph?
no. they can only detect them when presented to them by B cells, dendritic cells or macrophages
how so cytotoxic T cells kill infected cells?
they release perforin to create holes in cells
and they stimulate apoptosis
what causes cytotoxic T cells to bind to MHC-1 and not MHC-II?
cytotoxic T cells display CD8 which can bind to MHC I, whereas helper T cells display CD4 which are specific for MHC-II
do helper T cell bind to B cells in order to get them to differentiate into Plasma cells?
yes need to bind
are cytokines released in both innate and acquired?
yes
immune response to extracellular bacteria from wound
bacteria activates complement proteins which 1. activate mast cells 2. make MAC to lyse bacteria 3. act as opsonins 4. act as chemotaxis which attract circulation WBC to come in and phagocytes bacteria –> present antigen on MHC-II to activate helper T cells to activate B cells to turn to plasma cells and secrete more antibodies
- lastly, plasma proteins ( antibodies, acute phase proteins) come to scene to help out as opsonins
immune response to viruses
pre-existing antibodies act as opsonins, allowing macrophages to recognize them for phagocytosis–> present on MHC-II, recognized by helper T cell–> activates B cell to turn to plasma cells to secrete more antibodies.
Helper T cell also secretes cytokines which 1. activate cytotoxic T cells to become activated and release perforin to kill infected cells 2. are interferons that prevent more cells from getting infected ( up their defence)
- MHC-I on random infected cells can also activate cytotoxic T cells
immune response to allergy (1st vs 2nd exposure )
an allergenic response is a inappropriate inflammation response to a harmless substance.
1st exposure: all dandy -allergen get engulfed by macrophages, presented on MHC-II, activates Helper T cell, which activates B cells to differentiate into plasma cells to secrete antibodies and become memory cells
2nd exposure: not dandy- antigen enters, already have antibodies for ir, IgE on mast cells release histamine, IgG activates complement proteins and cytokine release all lead to inflammation
MHC-II on B cells, dendritic ells and macrophages activates
helper T cells
MHC-I on infected random ass cell activates
cytotoxic T cells
why is an allergic reaction so fast?
because we already have the antibodies ready fro fast attack when allergen enters
what happens n autoimmune diseases
antibodies are produced against normal body substances–> immune response (inflammation )
graves disease
antibodies against TDH receptor on thyroid cells
rheumatoid arthritis
antibodies produced against collagen
multiple sclerosis
antibodies against myelin
diabetes
antibodies against pancetic B cells
what hypothesis describes why there is an increasing number of autoimmune and allergic diseases?
the hygiene hypothesis - resulting in a decreased number of infections
CD8
cytotoxic T cells- MHC-I
CD4
helper T cells- MHC-II
IgE
allergy mediated antibody
IgG
alwaysi first to appear
IgA
all secretory
