Immune system Ch 21 Flashcards
2 types of immunity
Innate
Adaptive
Innate immunity/non-specific
First line defense, skin and body membranes.
Second line: hallmark is inflammation and consists of antimicrobial proteins, phagocytes and other cells that inhibit invaders.
Involves lectins
Adaptive Immunity/specific
Third line of defense, consists of humoral and cellular immunity
Involves antibodies
Attack specific invaders and is slower to respomd
Protective materials in skin and mucous membranes
Acid mantel of the skin
Enzymes: found in saliva, respiratory mucus and eye.
Mucin: lines the digestive and respiratory tracts
Defensins: broad spectrum antimicrobial peptides secreted by the skin and mucus membranes
Other chemicals: in the skin sebum and eccrine sweat are toxic to bacteria.
Phagocytes
Neurophils: most abundant
Macrophages: most voracious and derive from monocytes
Opsonization
Any pathogen that is coated with complement proteins called opsonins. These are markers to identify them as an invader.
Natural Killer cells
Police the blood and immune system to find and lyse cancer and virus infected cells before the adaptive immune system is activated.
Inflammation response
Triggered when ever there is tissue damage
Prevents the spread of damaging agents to surrounding tissue
Disposes of cell debris and pathogens
Alerts adaptive immune system
Sets the stage for repair
Mast cells are a key component and release histamine
Phagocyte mobilization
Leukocytosis: Neurophils enter the blood from bone marrow
Margination: Neurophils cling to capillary wall
Diapedesis: They then flatten and squees out of the capillary
Chemotaxis: neutophils follow chemical trail.
Chemotaxis
Inflammatory chemicals act as homing devices and WBC migrate to the site of inflammation
Interferons
Small proteins that help protect cells that have not yet been infected. IFN’s diffuse to nearby cells from infected cells and interfer with viral replication of DNA and blocking protein synthesis
Complament System
The major mechanism of destroying foreign substances in the body. A group of 20 plasma proteins that normally circulate in the blood. When activated they lyse and kill invaders
Complements both active and innate immune systems
3 important factors of adaptive response
It is specific
It is systemic
it has memory
Humoral immunity
Antibody mediated immunity, provided by antibodies present in the bodies fluids.
Cellular Immunity
Cell-mediated immunity: when lymphocytes themselves rather than antibodies, defend the body.
Directly: by killing infected cells
Indirectly: by releasing chemicals that enhance the inflammatory response and activate other WBCs
Antigens
Substances that can mobilize active defenses and provoke immune responses. Not normally in the body and recognized as not self
Complete antigens
Immunogenicity: the ability to stimulate specific lymphocytes to multiply
Reactivity: the ability to react with activated lymphocytes and antibodies
Incomplete antigens
Unless attached to a protein carriers hapens have reactivity but not immunogenicity.
MHC Proteins
A group of glucoproteins that are on the cell surface and identify it as self.
B Cells
Oversee humoral immunity, Activate helper T cell (not naive)
T Cells
Non-antibody producing, cellular arm of adaptive immunity
T Cell education is composed of
Positive and negative selection in the thymus
Positive selection
The first test the T cells must pass. It ensures that only the T cells that can recognize self-MHC proteins survives
Negative selection
The second test makes sure that T cells do not recognize self-antigens displayed on self-HMC.
Antigen presenting cells
APC Engulf antigens and present pieces of them on their surfaces like flags for the T cells to recognize.
Dendritic Cells
Found in the bodies frontiers (skin) where they act as sentinels with wispy extensions, very efficient antigen catchers/presenters. One of the key links between innate and adaptive immunity.
Memory Cells
Clone cells that do not become plasma cells. They can mount an almost immediate humoral response if they encounter the same antigen again in the future.
Primary immune response
Occurs on the first exposure to an antigen. Lag time of 3-6 days.
Secondary immune response
When someone is reexposure to the same antigen, faster more prolonged and more effective than primary responses. Provide immunological memory
Active humoral immunity
When B cells encounter antigens and produce antibodies against them
Passive humoral immunity
Instead of being made in your plasma, ready made antibodies are introduced into your body. In this case B cells are not challenged by antigens and immunological memory does not occur and protection is borrowed and temporary.
Antibodies
Also called immunoglobulins. Proteins secreted in response to an antigen by B cells called plasma cells and antibodies bind specifically with that antigen.
Antibody classes
MADGE
IgM:readily fixes and activated complament
IgA: Found in body secretions
IgD: Found on B Cell surface, antigen receptor
IgG: Most abundant in plasma, fixes and activates complament
IgE: binds to mast cells and basophils and stimulates inflmmation and allergic reaction
Antigen-Antibody complexes
Neutralization
Agglutination
Precipitation
Complement
Neutralization
Masks dangerous parts of bacterial exotoxins: viruses. As a result they cannot bind to receptors on tissue cells. Then phagocytes come in
Agglutination
Cross linked antigen complexes form lattices and cause the cells to clump together
Precipitation
Cross linked molecules are into large complexes. Soluble antigens.
Complement fixation and activation
The chief antibody used against cellular antigens. Multiple antibodies bind to invaders cell membrane which allows materials in to lyse the cell
Cellular immunity
CD4: Usually become helper T cells that help activate B cells and other T cells and macrophages
Some become regulatory T cells which moderate immune response.
CD8: Become cytoxic T cells,that destroy any cells in the body that harbor anything foreign.
