Exam 3 Live Lecture Review - Immune System & Microbial Diseases Flashcards

A comprehensive vocabulary flashcard set covering Course Outcomes 9 and 10 from the Exam 3 review lecture, including host defenses, innate and adaptive immunity, cell types, phagocytosis, complement, antibody classes, T-cell mechanisms, and microbial diseases across all organ systems.

Innate immune response

The arm of host defense that contains the first and second lines of defense and acts non-specifically.

Acquired immune response

The arm of host defense that includes the specific third line of defense involving B cells and T cells.

First line of defense

Host defense mechanisms consisting of physical, microbiota, and chemical barriers designed to prevent pathogens from entering the body.

Second line of defense

Cellular and chemical host defense system including phagocytes, inflammation, fever, and antimicrobial products.

Third line of defense

The specific immune response mediated by B cells and T cells that targets specific foreign antigens.

Physical barriers

Anatomical structures such as skin, cilia in the respiratory tract, and mucus that physically block pathogen entry.

Chemical barriers

Host secretions such as sweat, tears, earwax, lactoferrin, lysozyme, and skin pH that inhibit micro-organisms.

Microbiota barriers

Good bacteria occupying host tissues that help block pathogen colonization as part of the first line of defense.

Lactoferrin

An early chemical barrier found in tears and secretions that protects the host by binding iron.

Lysozyme

An enzyme present in tears and cell lysosomes that breaks down bacterial cell walls.

Cilia

Hair-like physical structures in the respiratory tract that sweep pathogens out of the body as part of the first line of defense.

Neutrophils

Phagocytic granulocytes found in the blood that are the first to respond to infection and increase during bacterial infections.

Eosinophils

Granulocyte leukocytes involved in allergic reactions as well as immune responses against protozoa and helminth worms.

Basophils

Granulocytes found in the blood that traffic into tissues and differentiate into mast cells.

Mast cells

Tissue-resident cells derived from basophils that contain and release histamine during inflammatory responses.

Monocytes

Agranulocytes in the blood that traffic into tissues to differentiate into macrophages or dendritic cells.

Macrophages

Tissue-resident phagocytic agranulocytes that function as antigen-presenting cells.

Dendritic cells

Phagocytic agranulocytes located in tissues that function as professional antigen-presenting cells.

Antigen-presenting cells (APCs)

Phagocytic cells—specifically monocytes, macrophages, dendritic cells, and B cells—that process and present antigens to T cells.

Lymphocytes

A category of leukocytes that includes T cells, B cells, and natural killer cells.

T cells

Specific lymphocytes possessing T-cell receptors that mediate cell-mediated adaptive immunity.

B cells

Specific lymphocytes possessing B-cell receptors that mediate humoral immunity and differentiate into antibody-secreting plasma cells.

Natural killer (NK) cells

Non-specific cells derived from the lymphocyte lineage that destroy cells lacking self-tag MHC Class I molecules.

T-cell receptor (TCR)

The specific surface receptor molecule present on T cells that recognizes antigen presented on MHC molecules.

B-cell receptor (BCR)

A Y-shaped receptor on B cells composed of two heavy chains and two light chains with constant and variable regions.

Chemotaxis

Step one of phagocytosis where phagocytes move toward chemical signals, such as histamine, at the site of injury.

Adhesion (Binding)

Step two of phagocytosis involving the specific binding interaction between microbial pathogen-associated molecular patterns (PAMPs) and phagocyte pattern recognition receptors (PRRs).

Pathogen-Associated Molecular Patterns (PAMPs)

Microbial surface molecules like peptidoglycan, flagella, LPS, and teichoic acids absent on human eukaryotic cells.

Pattern Recognition Receptors (PRRs)

Receptors located on phagocytic cells that specifically recognize and bind to microbial PAMPs.

Peptidoglycan

A major component of bacterial cell walls that serves as a PAMP recognized by host PRRs.

Lipopolysaccharide (LPS)

An outer membrane endotoxin component of Gram-negative bacteria that functions as a PAMP.

Teichoic acids

Molecules present in Gram-positive bacterial cell walls that function as PAMPs.

Phagocytic vacuole

The cellular vesicle formed around an engulfed pathogen during step three of phagocytosis.

Phagosome

The membrane-bound vesicle formed inside a phagocyte containing the ingested microbe in step four of phagocytosis.

Lysosome

A cytoplasmic organelle packed with destructive enzymes like lysozyme, DNase, and RNase used in phagocytosis.

Phagolysosome

The vesicle resulting from the fusion of a lysosome with a phagosome in step five of phagocytosis.

Destructive enzymes

Lysosomal chemicals including lysozyme, DNase, and RNase that destroy pathogens in the phagolysosome.

Exocytosis of debris

The final step of phagocytosis where microbial waste is released, though some antigens are retained for T-cell presentation.

Bacterial capsule

A thick sugar layer surrounding certain bacteria that covers PAMPs, preventing PRR binding and phagocytosis.

Mycobacterium tuberculosis phagocytosis evasion

The mechanism by which Mycobacterium tuberculosis inhibits phagolysosome formation or survives inside the phagolysosome to replicate.

Interferon

A cytokine released by virally infected cells that binds to neighboring uninfected cells to induce an antiviral state.

Antiviral state

A protective state induced by interferon in neighboring cells that halts protein synthesis and degrades viral nucleic acids.

Complement system

A multi-protein cascade system that enhances antibody function and culminates in the formation of membrane attack complexes.

Classical pathway

One of the three complement pathways initiated by the binding of antibodies to antigens.

Lectin pathway

One of the three complement pathways initiated by host lectins binding to microbial sugars.

Alternative pathway

One of the three complement pathways initiated directly by microbial surface molecules without antibody involvement.

Complement protein C3

The central complement protein formed by all three complement pathways prior to membrane attack complex assembly.

Membrane Attack Complex (MAC)

The end product of complement activation that pokes holes in microbial membranes, disrupting homeostasis and causing lysis.

Specificity

The property of adaptive immunity that directs responses against precise, individual pathogens rather than generalized microbes.

Diversity

The characteristic of adaptive immunity describing the vast range of unique antigen receptors produced by the body.

Inducibility

The characteristic of adaptive immunity where specific cells are activated only upon direct interaction with their matching antigen.

Clonality

The proliferation of a single activated lymphocyte into a large population of identical daughter cells.

Self-tolerance

The fundamental property of the adaptive immune system that prevents it from reacting against host self-cells.

Immunological memory

The capacity of adaptive immunity to mount a faster, stronger, and more robust response upon secondary pathogen exposure.

Antigen

Any molecular structure that can be seen, identified, and responded to by the immune system.

Epitope

The precise localized region on an antigen that is specifically recognized and bound by an antibody or receptor.

Hapten

A small molecule that is non-antigenic on its own but triggers an immune response when conjugated to a host carrier protein.

Heavy chains

The two larger, identical polypeptide chains forming the inner structural base of a Y-shaped antibody molecule.

Light chains

The two smaller, identical polypeptide chains forming the outer arms of a Y-shaped antibody molecule.

Constant region

The lower structural portion of an antibody that determines its specific immunoglobulin class.

Variable region

The upper tip of an antibody structure that forms the specific antigen-binding site.

Bone marrow

The primary lymphoid organ where all blood cells are created and where B cells mature.

Thymus

The lymphoid organ where T cells mature and express either CD4 or CD8 co-receptors alongside T-cell receptors.

Helper T cell help

Cytokine signals provided specifically by CD4+ helper T cells required for full B-cell activation.

Plasma cells

Fully differentiated B cells packed with endoplasmic reticulum whose sole function is secreting antibodies.

Memory B cells

Long-lived B cells formed during activation that persist to provide enhanced secondary immune responses.

Monomer antibody

An antibody structural arrangement consisting of a single Y-shaped unit, characteristic of IgG, IgE, and IgD.

Dimer antibody

An antibody structural arrangement composed of two linked Y-shaped units, characteristic of IgA.

Pentamer antibody

A large antibody structural arrangement composed of five linked Y-shaped units, characteristic of IgM.

IgM

A pentameric antibody class that is the first produced during a primary immune response and the first formed by a fetus.

IgA

A dimeric antibody class predominantly located in body secretions such as mucus, tears, and breast milk.

IgD

A monomeric antibody class primarily present as a surface receptor on mature B cells.

IgG

The dominant monomeric antibody class in circulation (about 80%) that crosses the placenta to protect the fetus.

IgE

A monomeric antibody class associated with allergic reactions and immune defense against parasitic infections.

Antibody neutralization

The antibody action of binding to viral spikes or toxins to block them from infecting host cells or inflicting damage.

Antibody opsonization

The coating of pathogens with antibodies to enhance their engulfment by phagocytic cells.

Antibody agglutination

The cross-linking of pathogens by antibodies into large clumps to facilitate clearance.

Complement activation by antibodies

The process where antibody binding induces complement proteins to assemble on target surfaces and form membrane attack complexes.

CD4 co-receptor

A surface glycoprotein on helper T cells that specifically interacts with MHC Class II molecules.

CD8 co-receptor

A surface glycoprotein on cytotoxic T cells that specifically interacts with MHC Class I molecules.

MHC Class I

Surface molecules found on all nucleated cells in the body that present endogenous antigens to CD8+ cytotoxic T cells.

MHC Class II

Surface molecules found exclusively on antigen-presenting cells that present exogenous antigens to CD4+ helper T cells.

Helper T cells (CD4+)

T lymphocytes that activate other immune cells by releasing a diverse array of chemical cytokines.

Cytotoxic T cells (CD8+)

T lymphocytes that directly kill infected, cancerous, or abnormal body cells displaying foreign antigen on MHC Class I.

Cytokines

Soluble signaling proteins released by activated helper T cells and other leukocytes to manage immune communications.

Perforins

Proteins released by cytotoxic T cells that poke holes in the membrane of targeted abnormal cells.

Granzymes

Destructive enzymes released by cytotoxic T cells that enter target cells through perforin pores to digest proteins and induce cell death.

Primary immune response

The initial adaptive immune response taking 2 to 3 weeks to generate peak antibodies, producing IgM first followed by IgG.

Secondary immune response

A rapid memory-driven immune response occurring within 3 days, producing higher titers of specific IgG antibodies.

Natural active immunity

Immunity acquired through direct exposure to a live pathogen during ordinary life experiences.

Natural passive immunity

Immunity acquired naturally when maternal antibodies cross the placenta or enter an infant through breast milk.

Artificial active immunity

Immunity stimulated deliberately through medical vaccination to induce self-antibody and memory production.

Artificial passive immunity

Immunity acquired by medically injecting an individual with harvested antibodies from another human or animal source.

Necrotizing fasciitis

A rapidly spreading flesh-eating tissue infection characterized by massive bacterial enzyme degradation and superantigen release.

Clostridium perfringens

A Gram-positive spore-forming bacterium capable of causing necrotizing fasciitis as well as food poisoning.

Streptococcus pyogenes

Group A streptococcus bacterium that causes strep throat, necrotizing fasciitis, endocarditis, and scarlet fever.

Staphylococcus aureus

A Gram-positive bacterium capable of causing skin infections, necrotizing fasciitis, and endocarditis.

Superantigens

Bacterial toxins that aggressively stimulate T cells non-specifically, provoking hyper-inflammatory tissue damage.

Varicella-zoster virus (VZV)

Human Herpesvirus 3 (HHV-3), the causative agent of chickenpox upon primary infection and shingles upon reactivation.

Chickenpox rash

An itchy, fluid-filled vesicular rash caused by primary infection with varicella-zoster virus.