XII Glossary

Active immunity: Immunity developed when the body produces its own antibodies after exposure to a pathogen or vaccination. (Chapter 12.4)

Acute inflammation: A rapid immune response to injury or infection characterized by redness, heat, swelling, pain, and loss of function. (Chapter 12.4)

Allergens: Substances that trigger an allergic immune response in sensitive individuals. (Chapter 12.5)

Allergic responses: Specific types of hypersensitivity reactions that arise when the immune system reacts to allergens. (Chapter 12.5)

Allergist: A physician who specializes in the study and treatment of allergies and asthma. (Chapter 12.6)

Anaphylaxis: A severe, potentially life-threatening allergic reaction that can cause bronchoconstriction and swelling of the throat, leading to obstruction of the airway, as well as decreased cardiac output that can lead to shock. (Chapter 12.5)

Antibodies: Proteins produced by B cells that specifically recognize and bind to foreign antigens to help neutralize or destroy them. (Chapter 12.4)

Antigens: Substances that may trigger a defensive response from leukocytes of the immune system if the body does not recognize the antigen as belonging to “self.” (Chapter 12.4)

Benign cells: Grow and divide in a more controlled manner, remaining localized to a certain area. (Chapter 12.5)

Cancer: A generic term for many diseases in which cells escape regulatory signals. (Chapter 12.5)

Cell-mediated response: An immune response that involves T cells attacking infected or abnormal body cells directly, without using antibodies. (Chapter 12.4)

Chronic inflammation: Ongoing inflammation caused by foreign bodies, persistent pathogens, and autoimmune diseases such as rheumatoid arthritis. (Chapter 12.4)

Chyle: A milky fluid consisting of dietary triglycerides combined with other lipids and proteins that enters lacteals during fat absorption. (Chapter 12.3)

Histamine: A chemical released during inflammation that causes vasodilation and increased capillary permeability, leading to swelling and redness at the injury site. (Chapter 12.4)

Humoral immunity: Immunity involving B cells that produce antibodies to target and neutralize pathogens. (Chapter 12.4)

Hypersensitivity reaction: An exaggerated or inappropriate immune response to an antigen that causes tissue damage. (Chapter 12.5)

Immune system: A complex collection of cells and organs that destroy or neutralize pathogens that would otherwise cause disease or death. (Chapter 12.1)

Immunocompromised: An individual who has an impaired or weakened immune system. (Chapter 12.5)

Immunodeficiency: Refers to an inadequate immune response caused by immune system dysfunction. (Chapter 12.5)

Immunologist: A physician who specializes in the study and treatment of immune system disorders. (Chapter 12.6)

Immunology: The study of disorders of the immune system. (Chapter 12.6)

Incubation period: The length of time before symptoms appear after being exposed to the virus. (Chapter 12.5)

Interstitial fluid: The fluid that surrounds body cells and facilitates the exchange of nutrients, oxygen, and waste between blood and cells. (Chapter 12.2)

Interstitial space: The spaces between individual cells in the tissue. (Chapter 12.2)

Lacteals: Specialized lymphatic capillaries in the small intestine that absorb dietary fats and transport them as chyle. (Chapter 12.3)

Lymphatic capillaries: Small, thin-walled vessels that absorb interstitial fluid and transport lymph to larger lymphatic vessels. (Chapter 12.3)

Lymphatic system: A system of vessels, cells, and organs that carries excess fluids to the bloodstream and filters pathogens from the blood. (Chapter 12.1)

Lymphatic trunks: Large vessels that drain lymph from specific regions of the body and empty it into one of two lymphatic ducts. (Chapter 12.3)

Lymphedema: A chronic disease in which there is an increase of lymphatic fluid in the body. (Chapter 12.5)

Lymph node: Small, bean-shaped organs located throughout the lymphatic system, commonly found near the groin, armpits, neck, chest, and abdomen. (Chapter 12.2, Chapter 12.3)

Lymphoid nodules: Consist of a dense cluster of lymphocytes without a surrounding fibrous capsule. (Chapter 12.3)

Lymphoma: A form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes, the spleen, the liver, and other tissues. (Chapter 12.5)

Macrophage: A phagocytic cell in the bone marrow, liver, and spleen that removes worn-out red blood cells from circulation. (Chapter 12.4)

Malignant cells: Exhibit uncontrolled growth and rapidly divide, subsequently invading and causing damage to normal functioning cells. (Chapter 12.5)

Metastasis: The spread of cancer cells to other parts of the body. (Chapter 12.5)

Metastasize: The process by which cancer cells spread from the original tumor to other parts of the body. (Chapter 12.5)

Monocyte: A circulating cell that differentiates into either a macrophage or dendritic cell, which can be rapidly attracted to areas of infection. (Chapter 12.4)

Neutrophil: A type of granular white blood cell that makes up 50–70% of leukocytes and is essential for fighting bacterial infections. (Chapter 12.4)

Opportunistic infections: Infections that occur more often or are more severe in people with weakened immune systems than in people with healthy immune systems. (Chapter 12.5)

Passive immunity: Immunity gained by receiving antibodies from another source, providing temporary protection without the body producing its own antibodies. (Chapter 12.4)

Pathogens: Disease-causing organisms. (Chapter 12.1)

Phagocytosis: A type of endocytosis where the cell engulfs large particles or microorganisms (“cell eating”); commonly performed by immune cells like macrophages. (Chapter 12.4)

Specific (Adaptive) immune response: The body’s targeted defense against specific pathogens, involving activation of lymphocytes (B and T cells) that recognize and remember particular antigens. (Chapter 12.4)

Spleen: A major secondary lymphoid organ. (Chapter 12.3)

Thymus gland: A bi-lobed organ between the sternum and aorta that supports T-cell development and is most active during childhood, shrinking after puberty. (Chapter 12.3)

Tonsils: Lymphoid nodules located along the inner surface of the pharynx (throat) and are important in developing immunity to oral pathogens. (Chapter 12.3)