Ch. 8 Immune system

the immune system can be divided into ____ and ___ immunity

innate, adaptive

innate immunity

composed of defenses that are always active, but that cannot target a specific invader and cannot maintain immunologic memory. also called NONSPECIFIC immunity

adaptive immunity

composed of defenses that take time to activate, but that target a specific invader and can maintain immunologic memory. also called SPECIFIC immunity

immune cells come from the

bone marrow

the ___ and ___ ___ are sites where immune responses can be mounted, and in which B-cells are activated

spleen, lymph nodes

the ___ is the site of T-cell maturation

thymus

Gut-associated lymphoid tissue (GALT) includes the

tonsils and adenoids (both are in the mouth)

are Leukocytes (white blood cells) involved in immune defenses

yes

the skin acts as a physical barrier and secretes antimicrobial compounds such as

defensins

_____ on mucous membranes traps pathogens; in the respiratory system it is propelled upward by cilia and can be swallowed or expelled

mucus

tears and saliva contain _____, and antibacterial compound

lysozyme

how do the stomach and gut prevent infection

• stomach = produces acid that kills most pathogens

• gut = colonization help prevent overgrowth by pathogenic bacteria through competition

the _____ system (liver) can punch holes in the cell walls of bacteria, making them osmotically unstable

complement

______ are given off by virally infected cells and help prevent viral replication and dispersion to nearby cells

interferons

macrophages

• ingest pathogens and present them on major histocompatibility complex (MHC) molecules

• secrete cytokines

MHC class 1 (MHC-1) is present in all nucleated cells and displays _____ _____ (proteins from within the cell) to cytotoxic T-cells (CD8⁺ cells)

endogenous antigen

MHC class 2 (MHC-2) is present in professional antigen-presenting cells (macrophages, dendritic cells, some B-cells, certain activated epithelial cells) and displays ____ _____ (proteins from outside the cell) to helper T-cells (CD4⁺ cells)

exogenous antigen

____ cells are antigen-presenting cells in the skin

dendritic

what kind of cells attack cells not presenting MHC molecules, including virally infected cells and cancer cells

natural killer cells

______ include neutrophils, eosinophils, and basophils

granulocytes

_______ ingest bacteria, particularly opsonized bacteria (those marked with antibodies). They follow bacteria using ______

Neutrophils, chemotaxis

_____ are used in allergic reaction and invasive parasitic infections. They release histamine, causing an inflammatory response

Eosinophils

_____ are used in allergic reactions. Mast cells are related cells found in the skin

Basophils

Humoral immunity is centred on antibody production by plasma cells, which are activated

B-cells

_____ target a particular antigen

antibodies

antibodies contain two heavy chains and two light chains. They have a constant region and a variable region; the tip of the variable region is the

antigen-binding region

when activated the antigen-binding region undergoes _____ to improve the specificity of the antibody produced. Cells may be given signals to switch ____ of antibody (IgM, IgD, IgG, IgE, IgA)

hypermutation, isotypes

circulating antibodies can ____ pathogens (mark them for destruction), cause _____ (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens

opsonize, agglutination

cell-surface antibodies can activate ___ cells, or mediate ____ reactions

immune, allergic

Memory B-cells lie in wait for a second exposure to a pathogen and can them mount a more rapid and vigorous immune response, this is called

secondary response

cell-mediated (cytotoxic) immunity is centered on the functions of

T-cells

T-cells undergo maturation in the thymus through positive selection and negative selection, define these

• positive: only selecting for T-cells that can react to antigen presented on MHC

• negative: causing apoptosis in self-reactive T-cells

the peptide hormone ____ promotes T-cell development

thymosin

Helper T-cells (T_h or CD4⁺) respond to antigen on MHC-2 and coordinate the rest of the immune system, secreting ____ to activate various arms of immune defense

lymphokines

T_h1 cells secrete ____ _____, which activates macrophages

interferon gamma

T_h2 cells activate this type of cell primarily in parasitic infections

B-cells

cytotoxic T-cells (T_c CTL or CD8⁺) respond to antigen on MHC-1 and

kill virally infected cells

suppressor (regulatory) T-cells (T_reg) tone down the

immune response after an infection and promote self-tolerance

Memory T-cells serve a similar function to

memory B-cells

in _____ conditions, a self-antigen is identified as foreign, and the immune system attacks the body’s own cells

autoimmune

what is it called when a nonthreatening exposure incite an inflammatory response

an allergic reaction

immunization is a method of inducing _____ _____ (activation of B-cells that produce antibodies to an antigen) prior to exposure to a particular pathogen

active immunity

passive immunity

the transfer of antibodies to an individual

the ____ system is a circulatory system that consists of one-way vessels with intermittent lymph nodes

lymphatic

the lymphatic system connects to the cardiovascular system via the ___ ____ in the posterior chest

thoracic duct

the lymphatic system equalizes fluid distribution, transports fats and fat soluble compounds in ______, and provides sites for mounting immune responses

chylomicrons