2025-04-16 Microbiology For The Health Sciences

Flashcards on Immunity

Pathogens

Disease-causing agents, including viruses, bacteria, and fungi.

Innate Immunity

Defenses against any pathogen; rapid and present at birth.

Adaptive Immunity

Immunity or resistance to a specific pathogen; slower to respond and has memory.

Basophil

A granulocyte that releases histamines causing inflammation.

Eosinophil

A granulocyte that kills parasites with oxidative burst.

Mast Cell

A granulocyte that acts as an antigen-presenting cell and produces antibacterial peptides.

Neutrophil

A granulocyte that phagocytizes bacteria and fungi.

Monocyte

An agranulocyte; precursor to macrophages that perform phagocytosis.

Dendritic Cell

An agranulocyte that phagocytizes bacteria and presents antigens to T cells.

Natural Killer (NK) Cell

An agranulocyte that kills cancer cells and virus-infected cells.

Plasma Cell/B Cell

An agranulocyte that recognizes antigens and produces antibodies.

T Helper (TH) Cell

A type of T cell that secretes cytokines and binds to MHC class II molecules on antigen-presenting cells (APCs).

Cytotoxic T Lymphocyte (CTL)

A type of T cell that recognizes and kills specific 'nonself' cells and binds to MHC class I molecules.

T Regulatory (Treg) Cell

A type of T cell that destroys cells that do not correctly recognize 'self' cells.

Histamine (effect)

Dilates blood vessels, allowing macrophages to exit.

Immunity

The ability to ward off disease.

Susceptibility

Lack of resistance to a disease.

Physical Barriers (Immunity)

Skin, chemicals like salt in sweat, cells that can phagocytize, inflammation, fever and molecules like interferon and complement.

Adaptive Immunity Components

Involves antibody-producing cells and T cells, responding specifically to a pathogen.

Skin

Outer portion made of tightly packed epithelial cells containing keratin, a protective protein

Mucous Membrane

Epithelial layer that lines the gastrointestinal, respiratory, and genitourinary tracts and secretes mucus.

Mucus

Viscous glycoproteins that trap microbes and prevent tracts from drying out

Ciliary Escalator

Transports microbes trapped in mucus away from the lungs.

Sebum

Forms a protective film and lowers the pH (3–5) of skin.

Lysozyme

Destroys bacterial cell walls; found in perspiration, tears, saliva, and urine.

Normal Microbiota

Compete with pathogens via microbial antagonism.

Microbial Antagonism

Competition between normal microbiota and pathogens for space and nutrients.

Commensalism

One organism benefits while the other (host) is unharmed.

Opportunistic Pathogens

Normal microbiota that can cause disease if conditions are right.

Probiotics

Live microbial cultures administered to exert a beneficial effect.

Prebiotics

Chemicals (nutrients) that selectively promote the growth of beneficial bacteria.

Hematopoiesis

The production of blood cells and platelets, which occurs in the bone marrow.

Granulocytes

Leukocytes with granules in their cytoplasm that are visible with a light microscope.

Agranulocytes

Leukocytes with granules in their cytoplasm that are not visible with a light microscope.

Lymph

Plasma that carries microbes to lymph nodes where immune cells destroy pathogens.

Lymphoid Tissue

Contains lymphocytes and phagocytic cells.

Chemotaxis

Chemical signals that attract phagocytes to microorganisms.

PAMPs

Pathogen-associated molecular patterns on microbes.

TLRs

Toll-like receptors on phagocyte surfaces that attach to PAMPs.

Opsonization

Microorganism is coated with serum proteins, making adherence easier for phagocytes.

Phagosome

Engulfed microorganism that is enclosed in vesicle within a phagocyte.

Phagolysosome

Formed by the fusion of a phagosome and a lysosome, where digestion occurs.

Inflammation

Destroys injurious agent or limits its effects on the body and repairs damaged tissue.

Histamine

Causes vasodilation and increased permeability of blood vessels.

Kinins

Cause vasodilation, increased permeability of blood vessels, and chemotaxis.

Prostaglandins

Intensify the effects of histamine and kinins and help phagocytes move through capillary walls.

Leukotrienes

Increase permeability of blood vessels and help attach phagocytes to pathogens.

Cytokines

Cause vasodilation and increased permeability of blood vessels, stimulating macrophages.

Margination

Phagocytes stick to the endothelium of blood vessels.

Diapedesis

Phagocytes squeeze between endothelial cells to reach the site of infection.

Fever

Abnormally high body temperature.

Complement System

Serum proteins produced by the liver that enhance the immune system in destroying microbes.

Classical Pathway (complement)

Antibodies bind to antigens, activating complement proteins.

Alternative Pathway (complement)

Complement activation triggered by direct interaction with a microbe surface.

Lectin Pathway (complement)

Macrophages ingest pathogens, releasing cytokines that stimulate lectin production in the liver.

Cytolysis

Activated complement proteins create a membrane attack complex (MAC).

Interferons

Cytokines produced by cells; have antiviral activity.

Siderophores

Produced by some bacteria to compete with iron-binding proteins.

Antimicrobial Peptides

Short peptides produced in response to protein and sugar molecules on microbes that act as broad spectrum.