Lymphatic and Immune Systems

Innate immunity

A nonspecific immune response that protects against a variety of invaders immediately.

Adaptive immunity

A specific immune response that targets and destroys specific pathogens that evade innate defenses.

Immunity

Specific resistance to disease.

Inflammatory response

A response triggered when body tissues are injured, characterized by redness, heat, pain, and swelling.

Cardinal signs of inflammation

Redness, heat, pain, and swelling.

Histamine

An inflammatory chemical released by damaged cells that causes blood vessels to dilate.

Kinin

An inflammatory chemical that helps in the inflammatory response.

Phagocytosis

The process by which phagocytes such as neutrophils and macrophages engulf and digest foreign material.

Complement proteins

A group of at least 20 plasma proteins that enhance innate defenses and can cause cell lysis.

Interferons

Small proteins secreted by virus-infected cells that inhibit viral replication.

Fever

An abnormally high body temperature that is a systemic response to microbial invasion.

Antigens

Substances that can trigger an immune response.

Humoral immunity

A type of adaptive immunity provided by antibodies present in body fluids.

Cell-mediated immunity

A type of adaptive immunity that targets virus-infected cells, cancer cells, and foreign cells.

Self-antigens

Proteins present in our own cells that do not trigger an immune response.

Haptens

Incomplete antigens that can provoke an immune response when combined with our own proteins.

B lymphocytes (B cells)

Lymphocytes that produce antibodies and are responsible for humoral immunity.

T lymphocytes (T cells)

Lymphocytes that do not produce antibodies and are involved in cell-mediated immunity.

Immunocompetence

The capability of a lymphocyte to respond to a specific antigen.

Antigen-presenting cells (APCs)

Cells that engulf antigens and present fragments on their surface for recognition by T cells.

Clonal selection

The process in which a B cell binds to an antigen and undergoes rapid division to produce clones.

Plasma cells

B cells that produce antibodies against specific antigens.

Memory cells

Long-lived B cells that provide immunological memory against previously encountered antigens.

Active immunity

Immunity gained through the exposure to antigens, either naturally or artificially.

Passive immunity

Immunity obtained from another individual's antibodies, offering short-term protection.

Monoclonal antibodies

Antibodies produced from a single clone of cells and used in diagnosis and treatment.

IgM

An antibody class that can fix complement and is the first antibody produced in response to an infection.

IgA

An antibody class found mainly in secretions, such as mucus and tears.

IgD

An antibody class important in the activation of B cells.

IgG

The most abundant antibody in plasma that can cross the placental barrier.

IgE

An antibody class involved in allergic reactions.

Complement fixation

A process used by antibodies to flag pathogens for destruction by the immune system.

Neutralization

The process by which antibodies bind to viral or bacterial toxins, preventing them from causing harm.

Agglutination

The clumping of cells caused by the reaction of antibodies with antigens.

Precipitation

The formation of a complex between soluble antigens and antibodies that settles out of solution.

Cytotoxic T Cells

T cells that kill infected cells by inserting perforins into their plasma membrane.

Helper T Cells

T cells that recruit and help activate other immune cells.

Perforin

A toxic chemical released by cytotoxic T cells that creates pores in target cell membranes.

Granzymes

Enzymes released by cytotoxic T cells that induce apoptosis in infected cells.

Cytokines

Chemical messengers released by helper T cells to communicate with other immune cells.

APC (Antigen-Presenting Cell)

Cells that present processed antigens to T cells, activating them.

Self-tolerance

A state where T cells do not target the body’s own cells.

Naive T cells

Immature T cells that have not yet encountered their specific antigen.

B cell activation

The process by which B cells recognize antigens and respond by producing antibodies.

Antigen recognition

The ability of immune cells to identify and bind to specific antigens.

Thymus

The organ where T cells develop immunocompetence.

Bone marrow

The site where B cells mature and develop immunocompetence.

Lysosome

An organelle in phagocytes that contains enzymes to digest engulfed materials.

Monocytes

A type of white blood cell that can differentiate into macrophages and dendritic cells.

Pathogen

An agent that causes disease, including viruses, bacteria, fungi, and parasites.