Chapter 21 - The Immune System: Innate and Adaptive Body Defenses

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Part II

immunity

(medicine) the condition in which an organism can resist disease

innate defense system

responds immediately to protect the body from all foreign substances, whatever they are

adaptive defense system

Is aquired immunity due to infection or vaccination: Third line of defense mounts attack against particular foreign substances (Takes longer to react than innate system, Workds in conjunction with the innate system)

immune system

a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response

pathogens

Microbes that cause disease

phagocytes

Cells that use phagocytosis to engulf foreign organisms. The chief ___ are macrophages, created from monocytes.

lysozyme

an enzyme found in saliva and sweat and tears that destroys the cell walls of certain bacteria

neutrophils

A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.

phagocytosis

process in which phagocytes engulf and digest microorganisms and cellular debris

phagosome

Intracellular vesicle containing material taken up by phagocytosis.

phagolysosome

Intracellular vesicle formed by fusion of a phagosome with a lysosome, in which the phagocytosed material is broken down by degradative lysosomal enzymes.

adherence

process by which phagocytes attach to microorganisms through the binding of complementary chemicals on the cytoplasmic membranes

opsonization

process whereby opsonins make an invading microorganism more susceptible to phagocytosis

respiratory burst

metabolic change accompanied by a transient increase in oxygen consumption that occurs in neutrophils and macrophages when they have taken up opsonized particles. It leads to the generation of toxic oxygen metabolites and other anti-bacterial substances that attack the phagocytosed material.

inflammatory response

nonspecific defense reaction to tissue damage caused by injury or infection

mast cells

a vertebrate body cell that produces histamine and other molecules that trigger the inflammatory response.

histamine

amine formed from histidine that stimulates gastric secretions and dilates blood vessels

kinins

acute inflammation; increase vascular permeability, vasodilation, smooth muscle contraction, pain; made in liver

prostaglandins

A group of bioactive, hormone-like chemicals derived from fatty acids that have a wide variety of biological effects including roles in inflammation, platelet aggregation, vascular smooth muscle dilation and constriction, cell growth, protection of from acid in the stomach, and many more.

leukotrienes

potent biological substances produced from unsaturated fatty acids by mast cells that cause bronchospasm, attract inflammatory cells, and induce excessive mucus secretion

complement

one of a series of enzymes in the blood serum that are part of the immune response. (starts with C)

leukocytosis

an abnormal increase in the number of white blood cells in the blood as a result of infection (as in leukemia)

margination

the aggregating or lining up of substances along a surface or edge (eg, the lining up of white blood cells against the wall of a blood vessel during the inflammatory process)

diapedesis

passage of blood cells (especially white blood cells) through intact capillary walls and into the surrounding tissue

chemotaxis

movement by a cell or organism in reaction to a chemical stimulus

Phagocyte Mobilization

-leukocytosis
-inflammed areas release signaling proteins (selectins)
-margination
-diapedesis
-chemotaxis
-monocyte follows neurtrophils,become macrophage with 12hr

pus

a fluid product of inflammation

interferons

Antiviral proteins secreted by T cells

antimicrobial proteins

are short peptides that have a broad spectrum of antimicrobial activity. Besides killing a wide range of microbes, AMPs can attract dendritic cells and mast cells, which participate in immune responses. aka AMPs

complement system

Group of at least 20 proteins whose activites enhance or complement the body's other defense mechanisms. -destruction of pathogen-enhancement of phagocytosis-stimulation of inflammation

fever

elevated body temperature that occurs in response to infection

pyrogens

molecules that set the body's thermostat to a higher temperature. they are released by certain leukocytes

humoral immunity

specific immunity produced by B cells that produce antibodies that circulate in body fluids. (also called antibody-mediated immunity)

cellular immunity

Type of ACQUIRED IMMUNITY involving T-cell lymphocytes. Large numbers of activated lymphocytes are formed specifically to destroy the foreign agent. This is called what type of immunity?

antigens

foreign substances that trigger the attack of antibodies in the immune response.

nonself

Antigen recognized as foreign by an organism.

complete antigens

antigens that are able to stimulate the proliferation of specific lymphocytes and antibodies and to react with the activated lymphochytes and produced antibodies; can develop antibodies

reactivity

ability to react with the activated lymphocytes and antibodies released by immunogenic reactions.

hapten

small antigen incapable of stimulating antibody production unless attached to a "protein". E.g. ... Penicillin -- (aka. incomplete antigen)

antigenic determinants

otherwise known as epitopes; regions of the antigen that are recognized by immunoglobulin B cell receptors or T cell receptors

self-antigens

A term used to describe all the normal constituents of the body to which the immune system would respond were it not for the mechanisms of tolerance that destroy or inactivate self-reactive B and T cells.

MHC proteins

Major histocompatibility complex; A family of genes that encode a large set of cell surface proteins. Class I and class II molecules function in antigen presentation to T cells. Foreign molecules on transplanted tissue can trigger T cell responses that may lead to rejection of the transplant.

b lymphocytes

form in the bone marrow and release antibodies that fight bacterial infections (aka. b cells)

t lymphocytes

provide cell-mediated immunity and are processed by the thymus gland. (aka. t cells)

antigen-presenting cells

macrophages that break down pathogens and present the antigens so t cells can recognize them.

clone

a group of genetically identical cells or organisms derived from a single cell or individual by some kind of asexual reproduction

plasma cells

cells that develop from B cells and produce antibodies.

memory cells

B lymphocytes that do not become plasma cells but remain dormant until reactivated by the same antigen.

primary immune response

the initial immune response to an antigen, which appears after a lag of several days

secondary immune response

The adaptive immune response provoked by a second exposure to an antigen. It differs from the primary response by starting sooner and building more quickly.

immunological memory

The capacity of the immune system to make quicker and stronger adaptive immune responses to successive encounters with an antigen. Immunological memory is specific for a particular antigen and is long-lived.

active humoral immunity

involves B cells being exposed to antigen; develops immunological memory, long term protection. Naturally- through infection or contact with pathogen; Artificially- vaccine, dead or attenuated

vaccines

dose of a disabled or destroyed pathogen used to stimulate a long-term immune defense against the pathogen. A weakened form of the virus is given to the person so their immune system can build up immunity to the virus.

passive humoral immunity

received from donor, placental transfer and breast milk, administration of immune serum (antivenom)

antibodies

Specialized proteins that aid in destroying infectious agents. (aka. immunoglobulins "igs")

gamma globulin

a plasma protein containing the immunoglobulins that are responsible for immune responses

antibody monomer

basic structural unit of an antibody, composed of four polypeptides linked by disulfide bonds

H chains

heavy polypeptide chains of antibodies that pair with L chains to form a functional immunoglobulin molecule. The constant end binds to an isotype-specific receptor site of T cells at one end and the variable end on the opposite pole of the immunoglobulin molecule pairs with L chains and binds specifically to antigen on target cells

L chains

Identical to H chains but half as long.

antigen-binding site

The site on an immunoglobulin or T-cell receptor molecule that binds specific antigen.

neutralization

The mechanism by which antibodies binding to sites on pathogens prevent growth of the pathogen and/or its entry into cells. The toxicity of bacterial toxins can similarly be neutralized by bound antibody.

agglutination

An antibody-mediated immune response in which bacteria or viruses are clumped together, effectively neutralized, and opsonized.

precipitation

soluble molecules are cross-linked into large complexes that settle out the solution. (an immune complex)

complement fixation and activation

chief antibody defensed used against cellular antigens. (an immune complex)

helper T cells

T cells that help the immune system by increasing the activity of killer cells and stimulating the suppressor T cells

cytotoxic T cells

T cells that can kill other cells. Almost all cytotoxic T cells are CD8 T cells. Cytotoxic T cells are important in host defense against viruses and other cytosolic pathogens, because they recognize and kill the infected cells.

Class I MHC proteins

Found on virtually all body cells

Class II MHC proteins

protein found only on the surface of B lymphocytes, macrophages, and dendritic cells that serves as a reference point for self (looked for by T helper cells)

T Cell Activation

The stimulation of mature T cells by antigen presented to them by professional antigen-presenting cells. It leads to their proliferation and differentiation into effector T cells.

Antigen Binding

First step of T Cell Activation, caused by T cell antigen receptors binding to an antigen-MHC complex on the surface of an APC.

cytokines

chemicals released by T helper cells that stimulate B cells

interleukin 1 & 2

A cytokine secreted by a macrophage that is in the process of phagocytizing and presenting antigen. It in combination with the antigen, activates the helper T cell to produce IL2 and other cytokines.

T cell-independent antigens

-no T cell activation, no memory T cells
macrophage can't engulf CHO capsule unless opsonized by Ab (protective- hard to make Ab to CHO)
-infants under 2-> no T cell independent (susceptible to capsular pathogens)

T cell-dependent antigens

Most antigens require Helpter T Cells co-stimulation to activate B cells. These are called:

cytotoxic T cells

T cells that can kill other cells. Almost all cytotoxic T cells are CD8 T cells. Cytotoxic T cells are important in host defense against viruses and other cytosolic pathogens, because they recognize and kill the infected cells.

perforins

Chemicals secreted by certain lymphocytes that create holes in the membrane of a host cell which causes the host cell to swell and rupture

allergies

overreaction of the immune system to antigens

allergen

any substance that can cause an allergy

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