Chapter 18: Immunity and Infection

Infection

Invasion of the body by a microorganism

Pathogen

An organism that causes disease

Immune system

The body’s collective system of defenses that includes surface barriers as well as specialized cells, tissues, and organs that carry out immune response.

Lymphocyte

A type of white blood cell that carries out important functions in the immune system.

Antigen

A substance that triggers the immune response

Antibody

A specialized protein,produced by plasma cells, that can recognize specific antigens.

B cell

A type of lymphocyte that produces antibodies

T cells

Cells responsible for cell mediated adaptive immune reactions

Immunity

Resistance to infection

Adaptive immunity

Immunity to infection acquired by the activation of antigen-specific lymphocytes in response to infection other than immunization.

Immunization

The process of conferring immunity to a pathogen by administering a vaccine to a person

Vaccine

A preparation of killed or weakened microorganisms, inactivated toxins, or components of microorganisms that is administered to stimulate an immune response.

Allergy

An immune response to normally innocuous foreign chemicals and proteins that is characterized by specific symtoms such as sneezing, rash, and swelling.

Allergen

An substance, such as a pollen, that triggers an allergic reaction

Histamine

A chemical responsible for the dilation and increased permeability of blood vessels in the allergic and inflammatory responses.

Asthma

A disease in which chronic inflammation and periodic constriction of the airways cause wheezing, shortness of breath, and coughing.

Anaphylaxis

A severe systemic hypersensitivity reaction to an allergen characterized by difficulty breathing, low blood pressure, heart arrhythmia, seizure, and sometimes death.

Incubation Period

The period when bacteria or viruses are actively multiplying inside the body’s cells; usually a period without symptoms of illness.