Immune System
KEY IDEA: Lymphocyte Activation [Steps Below, Stay Strong]
(1) particular T cells are activated (2) those T calls help B cells become activated and secrete antibodies.
KEY IDEA: 4 General Steps of an Adaptive Immune Response (in both antibody and cell mediated)
1. Antigen encounter and recognition. 2. Lymphocyte activation. 3. Antigen clearance. 4. Development of immunological memory..
asthma
In an allergic reaction, a severe response to allergens that involves constriction of airways in the lungs.
memory B cells (other cloned B cells differentiate into these, ready for the next war against this same antigen, except they'll be much more effective this time)
In antibody-mediated immunity, a long-lived cell expressing an antibody on its surface that can bind to a specific antigen. A memory B cell is activated the next time the antigen is encountered, producing a rapid secondary immune response.
clonal expansion (activated T cells secrete other interleukins and stimulate this)
In antibody-mediated immunity, the proliferation of an activated CD4+ T cell by cell division to produce a clone of cells.
memory helper T cells (responsible for immunological memory)
In cell-mediated immunity, a long-lived cell differentiated from a helper T cell, which remains in an inactive state in the lymphatic system after an immune reaction has run its course and ready to be activated on subsequent exposure to the same antigen.
defensins
In innate immunity, antimicrobial peptides that protect the epithelial surfaces against invading pathogens.
interleukin ("between leukocytes" released by APC activates the T cell)
In the antibody-mediated immune response, the molecule secreted by an antigenpresenting cell that activates the associated T cell.
systemic inflammation (if damage is extensive or infection spreads through the blood)
Inflammation that occurs throughout the body.
neutralization
One of two important mechanisms that clear foreign antigens from the body; toxins produced by an invading pathogen are inactivated (neutralized) from being bound by the antibodies.
agglutination
One of two important mechanisms to clear foreign antigens from the body, the immobilization of pathogens by antibodies; enhances phagocytic cells
antihistamines
Substances that block histamine receptors thereby reducing symptoms of an allergic reaction.
passive immunity (ex. placenta and breast milk, short-lived and body does not develop memory of the pathogen)
The acquisition of antibodies as a result of direct transfer from another person.
immune system
The body's system of defenses against disease, composed of certain white blood cells and antibodies.
immunological memory
The capacity of the immune system to respond more rapidly and vigorously to the second contact with a specific antigen than to the primary contact.
IgA
The class of antibodies found mainly in secretions at particular locations in the body; IgA functions to bind to surface groups on pathogens and block their attachment to body surfaces.
IgE
The class of antibodies secreted by plasma cells of the skin and tissues lining the gastrointestinal tract and respiratory tract that binds to basophils and mast cells to trigger the release of histamine, thereby causing an inflammatory response.
IgD
The class of antibodies that occurs with IgM as a receptor on the surfaces of B cells; the function of IgD is uncertain.
immune response
The defensive reactions of the immune system, including both the innate and adaptive systems.
IgM
The first antibody type secreted by B cells in a primary immune response.
KEY IDEA: Inflammation
The heat, pain, redness, and swelling that occur at the site of an infection.
heavy chains (2)
The heavier of the two types of polypeptide chains that are found in immunoglobulin and antibody molecules.; five C segments
adaptive (acquired) immunity
The inherited mechanisms leading to the synthesis of molecules that target pathogens in a specific way; one of two components of the immune system in vertebrates. It is not found in invertebrates.
innate immunity
The initial response by the body to eliminate cellular pathogens that involves mechanisms of the innate immune system.
light chains (2)
The lighter of the two types of polypeptide chains found in immunoglobulin and antibody molecules; one C segment.
IgG
The most abundant antibody type circulating in the blood and lymphatic system that is involved in primary and secondary immune responses.
clonal selection * * * * *END of Lymphocyte Activation Steps
The process by which a lymphocyte is specifically selected for cloning when it encounters a foreign antigen from among a randomly generated, enormous diversity of lymphocytes with receptors that specifically recognize the antigen.
immunological tolerance
The process that protects the body's own molecules from attack by the immune system.
autoimmune reaction
The production of antibodies against molecules of the body.
active immunity
The production of antibodies in the body in response to exposure to a foreign antigen.
secondary immune response (rapid due to memory B cells and memory T cells, IgG)
The rapid immune response that occurs during the second (and subsequent) encounters of the immune system of a mammal with a specific antigen.
B-cell receptors
The receptors studded in the plasma membrane of B cells that are specific for a particular antigen; Consist of four polypeptide chains.
antigen binding sites
The region at one end of an antibody molecule, T-cell receptor (TCR), or B-cell receptor (BCR) that binds to a specific antigen.
primary immune response (IgM is the main antibody in this first attack)
The response of the immune system to the first challenge by an antigen.
epitopes (antigenic determinants)
The small region of an antigen molecule to which BCRs or TCRs bind.
latent state
The time during which an animal virus (such as a pathogen) remains in an infected cell in an inactive form and cannot be isolated and identified.
CD4+ T cell (becomes linked to APC)
a T cell with CD4 receptors that interact with class II MHC proteins of an APC.
CD8+ T Cell (recognizes and binds to the antigens on the class I MHC proteins of an infected (APC) host cell.
a cell that has CD8 receptors on its surface in addition to T-cell receptors
2nd line of defense
a series of generalized and non-specific internal chemical, physical, and cellular reactions that attack pathogens that have breached the first line, involving mechanisms of the innate immune system.
B cells (recognize antigens and attack invaders outside cells)
a type of lymphocyte that recognizes antigens in the body; differentiate from stem cells in the bone marrow. Present before the body has encounter the antigens.
T cells (recognize antigens and attack invaders inside cells)
a type of lymphocyte that recognizes antigens in the body; originate from stem cells in the bone marrow and mature in the thymus
phagocytes, phagocytosis
a white blood cell that engulfs bacteria or other cellular debris to break them down, this process is known as phagocytosis.
AIDS
acquired immunodeficiency syndrome, a constellation of disorders that follows infection by HIV.
hybridomas (activated B cells are extracted and combined with myeloma (cancer) cells to form these; used in STD tests, cancer screenings, pregnancy tests)
composite cell formed between an activated B cell and cancerous lymphocytes called myeloma cells; cloned into highly specific (monoclonal) antibodies.
antibody class (5 listed below)
different constant regions of the heavy chains in the tail part of the Y-shaped structure determine this.
pathogens
disease-causing viruses or organisms such as infectious bacteria, protists, fungi,, and parasitic worms.
innate immune system
found in all animals, the inherited mechanism that protect the body from many kinds of pathogens in a nonspecific way.
adaptive immune system
found only in vertebrates, the inherited mechanisms leading to the synthesis of molecules that target pathogens in a specific way.
HIV
human immunodeficiency virus, leads to AIDS
local inflammation
inflammation that occurs at the site of the infection.
3rd line of defense
involves mechanisms of the adaptive immune system and targets pathogens in a very specific way: recognizing individual pathogens and mounting an attack that neutralizes or eliminates them directly.
memory cytotoxic T cells
long-lived cells that enable a rapid response should the same antigen be encountered on infected cells in the future
Major Types of Leukocytes
monocyte, lymphocyte, basophil, neutrophil macrophage, eosinophil, (MLBNME)
pathogen-associated molecular patterns (PAMPs)
pathogen-specific molecules that are recognized by the innate immune system.
leukocytes (white blood cells)
responsible for the activities of the two immune systems, eliminating dead and dying cells from the body, removing cellular debris, and participating in defending the body against invading organisms.
cytotoxic T cells (activated CD8+ T cell by this linkage and the cytokines already released by helper T cells in the antibody-mediated immune system, proliferate into clones, these ones combat the infection with perforins)
A T lymphocyte that functions in cell-mediated immunity to kill body cells infected by viruses or transformed by cancer.
effector T cell (ex: helper T cell, cytotoxic T cell)
A cell involved in effecting—bringing about—the specific immune response to an antigen.
antigen-presenting cell (APC) (now it's called this)
A cell that presents an antigen to T cells in antibody-mediated immunity and cell-mediated immunity.
helper T cells (clones differentiate into this and meanwhile the B cells engulfed the same pathogen and are ready to link with and be activated by these helper T cells)
A clonal cell that assists with the activation of B cells.
class II major histocompatibility complex (MHC) proteins (where the antigens are presented on the dendritic cell)
A collection of proteins that present antigens on the cell surface of an antigen-presenting cell in an antibody-mediated immune response.
fever (may result from systemic inflammation)
A condition characterized by a rise in body temperature above the normal range.
KEY IDEA: interferons (type of cytokine synthesized and released by a cell when infected by a virus)
A cytokine produced by infected host cells affected by viral dsRNA, which acts both on the infected cell that produces it, an autocrine effect, and on neighboring uninfected cells, a paracrine effect.
antigen
A foreign molecule that triggers an adaptive immunity response.
KEY IDEA: antibodies (secreted by plasma cells --> recognizes, binds to, and clears antigens from body; stimulates complement system and phagocytosis; 4 polypeptide chains: 2 light, 2 heavy)
A highly specific and large Y-shaped soluble protein molecule that circulates in the blood and lymph, recognizing and binding to antigens and clearing them from the body.
plasma cells (activated B cell proliferates and differentiates into this (or memory B cells); short-lived, secreting the same antibodies on the B cell surface into the blood and lymph to immediately attack the pathogen!)
A large antibody-producing cell that develops from B cells.
lymphocyte (examples: NK cells, B cells, T cells, plasma cells)
A leukocyte that carries out most of its activities in tissues and organs of the lymphatic system. The main subtypes of lymphocytes play major roles in innate and adaptive immunity.
autoimmune disease
A malfunction of the immune system in which the body reacts against its own proteins or cells.
cytokines (secreted by macrophages) *(also secreted by dendritic cell as interleukins that activate T cell)*
A molecule secreted by one cell type that binds to receptors on other cells and, through signal transduction pathways, triggers a response. In innate immunity, cytokines are secreted by activated macrophages.
KEY IDEA: complement system *(antibodies bound to pathogens stimulate this)
A nonspecific defense mechanism activated by invading pathogens, made up of more than 30 interacting soluble plasma proteins circulating in the blood and interstitial fluid.
toll-like receptors
A pattern-recognition receptor in innate immunity that is found on the cell surface and within the cell on various membrane-bound compartments. Each type recognizes a different, specific set of molecular patterns on pathogens.
chemokines (attracts neutrophils and monocytes to infection site to engulf the pathogens)
A protein secreted by activated macrophages that attracts other cells, such as neutrophils.
perforin (protein secreted by NK cells and cytotoxic T cells to create pores in infected cell)
A protein secreted by natural killer cells of the immune system that creates pores in a virusinfected cell's membrane.
T-cell receptors
A receptor that covers the plasma membrane of a T cell, specific for a particular antigen; Two different polypeptides.
anaphylactic shock (can be countered with immediate injection of epinephrine (adrenaline), which reverses the condition by constricting the blood vessels and dilating air passages in the lungs)
A severe inflammation stimulated by an allergen, involving extreme swelling of air passages in the lungs that interferes with breathing, and massive leakage of fluid from capillaries that causes blood pressure to drop precipitously.
immunoglobulin [ Ig ]
A specific protein substance produced by plasma cells to aid in fighting infection.
KEY IDEA: allergens
A type of antigen responsible for allergic reactions, which induces B cells to secrete an overabundance of IgE antibodies.
mast cells (activated from tissue damage)
A type of cell dispersed through connective tissue that releases histamine when activated by the death of cells, caused by a pathogen at an infection site.
basophils (mast cells also respond to IgE antibodies)
A type of leukocyte located in blood that responds to IgE antibodies in an allergic response by secreting histamine, which stimulates inflammation.
monocytes (build-up on blood vessel walls that are stickier due to released cytokines)
A type of leukocyte that enters damaged tissue from the bloodstream through the endothelial wall of the blood vessel and then differentiates into a macrophage.
eosinophils (needed if pathogen is too large)
A type of leukocyte that secretes substances that kill eukaryotic parasites such as worms.
KEY IDEA : natural killer (NK) cells (circulates through blood and targets viral host cells that secrete interferons)
A type of lymphocyte that destroys virus-infected cells.
dendritic cell (engulfs bacterium, degrades it and releases its antigens)
A type of phagocyte, so called because it has many surface projections that resemble dendrites of neurons, which engulfs a bacterium in infected tissue by phagocytosis.
macrophages ("big eaters" that recognize pathogens with their toll-like receptors)
A type of phagocytic leukocyte that engulfs infected cells, pathogens, and cellular debris in damaged tissues, and helps activate lymphocytes carrying out an immune response.
neutrophils (build-up on blood vessel walls that are stickier due to released cytokines)
A type of phagocytic leukocyte that engulfs pathogens and tissue debris in damaged tissues.
apoptosis (proteases secreted by NK cells infiltrate infected cells and activate DNA degradation)
A type of programmed cell death.
KEY IDEA: antibody-mediated immunity
Adaptive immune response in which plasma cells secrete antibodies. Also called humoral immunity.
membrane attack complexes
An abnormal activation of the complement (protein) portion of the blood, forming a cascade reaction that brings blood proteins together, binds them to the cell wall, and then inserts them through the cell membrane.
memory cells (occurs in step 4)
An activated lymphocyte that circulates in the blood and lymph, ready to initiate a rapid immune response on subsequent exposure to the same antigen.
KEY IDEA: cell-mediated immunity
An adaptive immune response in which a subclass of T cells—cytotoxic T cells—becomes activated and, with other cells of the immune system, attacks host cells infected by pathogens, particularly those infected by a virus.
KEY IDEA: monoclonal antibodies
An antibody that reacts only against the same segment (epitope) of a single antigen.
Systemic lupus erythematosus (lupus)
An autoimmune disease caused by production of a wide variety of anti-self antibodies against blood cells, blood platelets, and internal cell structures and molecules such as mitochondria and proteins associated with the DNA in the cell nucleus; characterized by anemia and problems with blood circulation and kidney function.
Multiple sclerosis
An autoimmune disease resulting from an attack against a protein of the myelin sheaths insulating the surfaces of neurons, causing muscle weakness and paralysis.
Rheumatoid arthritis
An autoimmune disease that results by a self-attack on connective tissues, particularly in the joints, causing pain and inflammation.
histamine (released by mast cells to cause inflammation)
An inflammatory signaling molecule that works with cytokines to dilate blood vessels, increase their permeability and increase blood flow, causing heat, redness & swelling of inflammation.
thymus
An organ of the lymphatic system that plays a role in filtering viruses, bacteria, damaged cells, and cellular debris from the lymph and bloodstream, and in defending the body against infection and cancer; where lymphocytes migrate to mature.
1st line of defense
the body surface-the skin covering the body exterior and the epithelial surfaces covering internal body cavities and ducts, such as the lungs and intestinal tract.
physical barriers
the main component of the 1st line of defense; not part of the immune system.
pyrogens (chemicals released by macrophages that may induce fever)
Chemicals released by macrophages in response to infection that stimulate prostaglandin release from the hypothalamus thereby leading to an increase in body temperature (fever).
vaccination *(relies on immunological memory)
the process of administering a weakened form of a disease to patients as a means of giving them immunity to a more serious form of the disease.
constant (C) region (lower)
For the light and heavy polypeptides of a particular type of antibody molecule, the bottom regions that have the same amino acid sequences for all molecules.
variable (V) region (higher)
For the light and heavy polypeptides of a particular type of antibody, the regions that have different amino acids sequences from molecule to molecule.