Chap 15

Immune System

A complex network that protects the body against infection by pathogens and foreign substances.

Leukocytes

White blood cells (WBC) involved in immune responses, varying in function and structure.

Phagocytosis

The process by which certain cells engulf and digest microorganisms, debris, and foreign particles.

Innate Immunity

The non-specific first line of defense against pathogens, including physical barriers and immune responses.

Adaptive Immunity

The specific immune response characterized by memory and slower initial response, involving the activation of lymphocytes.

Inflammation

A localized response to tissue injury or infection characterized by redness, heat, swelling, and pain.

Cytokines

Signaling proteins released by immune cells that mediate and regulate immunity and inflammation.

Antigen

Any foreign molecule capable of triggering an immune response.

Helper T Cells

Type of T lymphocyte that aids B cells and other T cells in the immune response.

Cytotoxic T Cells

Type of T lymphocyte that kills cancerous or virus-infected cells.

B Lymphocytes

White blood cells that produce antibodies and create a memory for future infections.

Major Histocompatibility Complex (MHC)

Proteins on cell surfaces that help display antigens for recognition by T cells.

Autoimmune Disease

A condition where the immune system mistakenly attacks the body’s own tissues.

Immunodeficiency

A state in which part of the immune system is missing or not functioning.

Hypersensitivity

An exaggerated immune response to an antigen that can cause tissue damage.

Complement System

A group of proteins in the blood that help antibodies and phagocytes clear pathogens.

Interferons

Cytokines released by virus-infected cells that inhibit viral replication and modulate the immune response.

Natural Killer (NK) Cells

A type of lymphocyte that can attack tumor and virus-infected cells without prior sensitization.

Memory Cells

Long-lived lymphocytes that retain information about a previous pathogen encounter for faster response on re-exposure.