the immune system Flashcards
innate immunity is?
nonspecific protection the body provides against various invaders
why is skin apart of innate immunity?
it is the first barrier against the entry of microorganisms
why are tears, saliva, and blood apart of innate immunity?
they contain lysozyme which kills some bacteria by destroying their cell walls
why is the stomach apart of innate immunity?
the extreme acidity destroys many pathogens ingested with food
why WBC are apart of innate immunity?
macrophages and neutrophils because they are first line of defense with WBC and phagocytize microorganisms such as bacteria, parasites, viruses
humoral immunity is?
specific protection by antigens (Ab) and immunoglobulins (Ig)
IgM:
location?
function?
blood and B cell surface
initial immune response
*IgM is pentameric (5 subunits) in blood and monomeric on B cells, as antigen receptor
IgG:
location?
function?
blood
involved in ongoing immune response
majority of antibody in the blood is IgG and can also cross placental barrier
IgD:
location?
function?
B cell surface
serves with IgM as antigen receptors
IgA:
location?
function?
secretions such as saliva, mucus, tears, breast milk
secreted in breast milk to help protect newborns
*has dimeric structure
IgE:
location?
function?
blood
involved in allergic reactions
an epitope is?
small site that an antibody recognizes within a larger molecule
an antigen (Ag) is?
molecule that an antibody binds to
*Ag are often large and have many different recognition sites for different Ab
Ab work to remove antigens by binding to it which results in three possible process?
1) the Ab bind inactivates Ag to prevent virus from binding to other cells
2) Ab binding can activate phagocytosis by macrophages and neutrophils
3) presence of Ab can active complement system to form holes in membrane and lyse the cell
why is the complement system is apart of innate immunity
it is a group of 20 blood proteins that nonspecifically bind to surface of foreign, leading to destruction
which lymphocyte activates plasma cells to produce antibodies?
B cells
when antigen binds to the antibody on the surface of an immature B cell, the cell proliferates and results as one of two cell types?
plasma cell or memory cell
if immature B cell becomes a plasma cell, what does it do?
it actively produces and secretes antibody into plasma
if immature B cell becomes a memory cell, what happens?
it does not secrete antibody but become a pre-activated, dormant B cell
how do memory cells become activated?
if the same antigen that start the process is presented again, it automatically produces the antibody very quickly (sometimes so quickly, no symptoms of illness become present)
primary immune response is defined as?
when a person encounters an antigen during an infection for the first time, it can take a week or more for B cells to proliferate and secrete significant levels of antibodies - which is too slow to prevent symptoms of illness
secondary immune response is defined as?
when a person encounters the same antigen, the B cells are much stronger and quicker to prevent symptoms from developing
vaccinations utilize which processes of B cells?
memory cells and secondary immune response
what are the two types of T cells?
T helpers (CD4 cells) T killers (CD8 cells)
T helpers work by?
activating B cells, T killer cells, and other cells of immune system
How do T helpers communicate to other cells?
by releasing lymphokines and interleukins (means activating other WBCs)
T killers work by?
destroying abnormal host cells such as, virus-infected host cells, cancer cells, and foreign cells (cells of skin graft from incompatible donor)
which T cell hosts the HIV virus?
T helpers
what does the T in T cells stand for and why?
thymus because T cells are only developed during childhood
how do T cells recognize bad cells?
by binding to protein surface and examining for the major histocompatibility complex (MHC)
MHC is programmed into all of our cells so that immune system can evaluate correctly
MHC I protein role is to?
pick up peptides from inside of cell and display them on surface for T cells to monitor cellular components
if a cell is infected with a virus, what does MHC I do?
it will display a piece of a virus-specific protein on surface so when T killers binds it will activate and proliferate
MCH II is only present in antigen-presenting cells (APCs), which are?
macrophages and B cells
APCs use MCH II by?
phagocytize particles or cells, chop them up, and display the fragments using MHC II system to help T helper recognize and activate B cells and T killers
another tissue involved in immune system is, bone marrow which?
site of synthesis of all cells of the blood from a common progenitor
the spleen is involved in immune response by?
filtering blood and is the site of immune cell interactions
spleen also destroys aged RBC
the thymus is involved in immune response by being?
site of T cell maturation
thymus shrinks with age thus maturing of immune system and T cells is most active in children
the tonsils are involved in immune response by?
being lymphatic tissue that catches pathogens that enter through respiration or injestion
the appendix is involved in immune response by?
similar to tonsils
tolerance of the immune system is when?
the system will only recognize and destroy foreign antigens and ignore all normal proteins and cell structures
because of the trillion different B and T cells being made, some of them become specific for normal molecules known as?
self-antigens
self-antigens in B cells are destroyed by?
happens in bone marrow
if immature B cell binds to normal cell surface proteins (such as MHC, macrophage, etc) it will die via apoptosis
if immature B cell binds to normal soluble protein (hemoglobin, lipoprotein), it will become anergic
self-antigens in T cells are destroyed by?
happens in thymus or lymph nodes
if immature T cell binds to normal proteins it become anergic
how are B and T cell clones created?
if original T or B cells proliferate in response to antigen in proper context, they will produced a group of identical T or B cells that are specific to the antigen they just targeted
self-antigens cells that are not destroyed result in?
autoimmune reactions where the immune system attacks normal body cells or proteins
