Microbio Exam 4 vocab

Axenic

a sterile state such as a pure culture…an axenic animal is born and raised in a germ-free environment

Opportunistic pathogen

a pathogen that infects a host when the body’s defense system is vulnerable…causes an opportunistic infection

Virulence factor

a product of microbes i.e. enzyme or toxin that increases the microbe’s invasiveness or pathogenicity

Hemolysin

any biological agent capable of destroying red blood cells and causing the release of hemoglobin

Endotoxin

bacterial intracellular toxin that is not ordinarily released like exotoxins are…

• Composed of a phospholipid-polysaccharide complex that is an integral part of gram-negative bacterial cell walls

• Can cause severe shock and fever

Exotoxin

toxin (usually protein) that secreted and acts upon a specific target

• Botulin, tetanospasmin diphtheria toxin, and erythrogenic toxin

Infectious dose

estimated number of microbial cells or units required to establish infection

Phagocytes

specialized cell where the cell membrane engulfs a large particle or cells into vesicles

Cytopathic effects

the degenerative changes in a cells associated with virus infection

• Cell lysis, foamy degeneration, and cell transformation, where cells become immortal and are used in diagnostics and to evaluate antiviral drugs

Prodromal period

 short period of nonspecific symptoms at the end of period of incubation that’s usually earliest indication of infection…stage of symptoms that occurs before full onset

Period of invasion

period during clinical infection when the infectious agent is multiplying at high levels, exhibits its greatest toxicity, and becomes well established in the target tissues

Convalescent period

recovery…the period between the end of a disease and the complete restoration of health in a patient

Chronic carrier

 individual who harbors a pathogen for a prolonged period without showing symptoms and intermittently or continuously shed the infection to others who do get sick

Incubation carrier

person who asymptomatically harbors an infectious agent during the incubation period and spread to others before they show symptoms

Focal infection

occurs when an agent breaks loose from a localized infection site and is carried by the circulation to other tissues

Nonsocomial infection

hospital-acquired infection is an infection acquired in a hospital or other healthcare facility

Syndrome

collection of signs and symptoms that, taken together, paint a portrait of the disease

Bacteremia

the presence of viable bacteria in circulating blood

Septicemia

systemic infection associated with microorganisms multiplying in circulating blood

Viremia

presence of viruses in the blood stream

Toxemia

abnormality associated with certain infectious diseases…caused by other toxins or noxious substances released by microorganisms circulating in the blood

Cytokines

chemical mediators that stimulate the movement and migration of white blood cells…help coordinate the immune response

Interleukins

protein secreted by leukocytes that regulate immune function

Chemokines

large family of small, secreted proteins (cytokines) that act as signaling molecules to guide the movement of immune system cells through chemotaxis 

Interferons

naturally occurring polypeptide produced by fibroblasts and lymphocytes that can block viral replication and regulate a variety of immune reactions

Pattern recognition receptors (PCRs)

proteins in the innate immune system that detect common molecular patterns found on immune cells e.g. toll-like receptors

Toll-like receptors (TLRs)

small surface receptors on phagocytes that are specialized to bind and react to pathogens

Pathogen-associated molecular patterns (PAMPs)

molecules on the surfaces of pathogenic microbes that are recognized by phagocytes and trigger immune responses against the microbes

Stem cells

undifferentiated cells found in the bone marrow and other organs that have the capacity to develop or differentiate into the lines of blood cells

Hematopoiesis

process by which various types of blood cells are formed by stem cells in the bone marrow 

Mast cells

type of white blood cell found in the connective tissues that play a key role in immune responses—particularly allergic reactions…mast cells contain and release chemical mediators like histamine to help fight off pathogens, manage inflammation, and repair tissue.

Macrophages

a white blood cell derived from a monocyte that leaves circulation and enters tissues…macrophages are important in nonspecific phagocytosis and in regulating, stimulating, and cleaning up after immune responses

Dendritic cells

large, antigen-presenting cell characterized by long, branchlike extensions of the cell membrane

T-cells

class of thymus stimulated lymphocytes that facilitate various immune activities i.e. assisting the activation of B cells and macrophages 

B-cells

responsible for producing antibodies to fight infections…they originate in the bone marrow…when activated can differentiate into plasma cells that secrete antibodies or memory B cells that provide long-term immunity

Erythrocytes

red blood cells…involved in the transport of oxygen and carbon dioxide 

Platlets

formed element in the blood that develops when megakaryocytes disintegrate…platelets are involved in homeostasis and blood clotting

Histamines

cytokine released when mast cells and basophils release their granules…important mediator of allergic reactions

Neutrophil

mature granulocyte present in peripheral circulation, exhibiting a multilobular nucleus and numerous cytoplasmic granules that retain a neutral stain…neutrophils are active phagocytic cell in bacterial infection

Pyrogen

a substance that causes a rise in body temperature…can come from infectious agents or from polymorphonuclear leukocytes and macrophages

Major histocompatibility complex (MHC)

set of genes that codes for human cell receptors…this gene complex gives rise to a series of glycoproteins called MHC molecules found on all cells except for RBCs

• Human leukocyte antigens (HLA) genes play an important role in the recognition of self by the immune system and in rejection of transplants

Antigen-presenting cells (APCs)

a macrophage or dendritic cell that ingests and degrades an antigen and subsequently places antigenic determinant molecules on its surface for recognition by CD4 T lymphocytes

• APCs modify the antigen so it’s more immunogenic and recognizable and then the antigen moves to the surface of the APC and binds to MHC class II receptor to make it readily acceptable to T cells during presentation 

Cytokines

small proteins that act as signaling molecules in the immune system to regulate cell growth, differentiation, and activity

Interleukins

protein excreted by leukocytes that regulate immune function

Monocolonal

an antibody produced by a clone of lymphocytes that respond to a particular antigenic determinant and generate identical antibodies only to that determinant 

Agglutination

the aggregation caused by antibodies when they cross-link cells or large particles into clumps that settle…agglutination renders microbes immobile and increases the speed with which they are phagocytized

Opsonization

process in which microorganisms or other particles are coated with specific antibodies so that they will be more readily recognized by phagocytes which dispose of them 

Antibody neutralization

antibodies fill the surface receptors on a virus or the active site on a bacterial protein which prevents them from attaching to their target cells

Immunoglobublin

the chemical class of proteins to which antibodies belong…large glycoprotein molecules that serve as the specific receptors of B cells (antibodies) 

Primary antibody response

a latent period with no measurable antibody occurs early on…te first antibody to appear is IgM, followed later by IgG arising from activation of the first memory cells…within weeks, the titer tapers back to low levels

Secondary antibody response

The rapid rise in antibody titer following a repeat exposure to an antigen that has been recognized from a previous exposure…this response is brought about by memory cells left behind after the primary exposure

Clonal selection theory

conceptual explanation of the development of lymphocyte specificity and variety during maturation of the immune system

• Undifferentiated lymphocytes in embryo and fetus undergo continuous series of divisions and genetic changes that generate hundreds of different cell types, each with a particular/unique receptor specificity