Lesson 9.3 The Lymphatic System

Vocabulary flashcards covering key terms and concepts from Lesson 9.3 The Lymphatic System.

Lymphatic system

A body system (often called the immune system) that defends against pathogens and includes organs such as the spleen, tonsils, adenoids, appendix, thymus, and lymph nodes.

Spleen

An organ that helps fight certain types of bacteria.

Vestigial organs

Organs once thought to be nonfunctional remnants of evolution; tonsils, adenoids, and appendix are now known to have active functions.

Tonsils

Lymphatic tissue at the back of the throat; involved in immune defense.

Adenoids

Lymphatic tissue located behind the nasal cavity; involved in immune defense.

Appendix

A small pouch connected to the large intestine; once thought vestigial, now known to have immune functions.

Thymus gland

Organ above the heart; secretes hormones that stimulate maturation of killer T cells; active from birth through puberty and then decreases in size.

B cells

Lymphocytes that label invaders with antibodies and can release antibodies into the bloodstream.

T cells

Lymphocytes that mature in the thymus and coordinate immune responses; include helper and killer T cells.

Helper T cells

Activate killer T cells and B cells; coordinate the immune response and produce defensive proteins.

Killer (cytotoxic) T cells

Attack and destroy infected body cells; can induce apoptosis in those cells.

Macrophages

White blood cells that phagocytose pathogens and infected cells and initiate immune alarm signals.

Phagocytosis

Process by which macrophages consume pathogens and infected cells.

Apoptosis

Programmed cell death of infected cells triggered by T cells.

Antibodies

Proteins on B cells or released into the bloodstream that attach to pathogens, marking them for destruction.

Vaccination

Introduction of dead or disabled pathogen or harmless microbe with pathogen protein to trigger immunity without infection; creates memory cells.

Memory cells

Long-lived B and T cells directed against a specific pathogen that provide immunity upon re-exposure.

Autoimmune disease

Condition in which the immune system attacks the body's own cells.

Systemic Lupus Erythematosus

Autoimmune disease affecting connective tissue, joints, and kidneys; symptoms include rash, fever, fatigue.

Type I Diabetes

Autoimmune destruction of insulin-producing cells in the pancreas.

Graves’ Disease

Autoimmune thyroid disorder causing hyperthyroidism.

Rheumatoid Arthritis

Autoimmune disease causing crippling inflammation of the joints.

HIV/AIDS

Virus that destroys macrophages and helper T cells; transmitted primarily through sexual intercourse; not airborne and not spread via casual contact.

Mast cells

Cells attached to white blood cells that release histamines when encountering matching antibodies, triggering inflammation.

Histamines

Chemical mediators that cause capillary dilation and increased mucus production during an inflammatory response.

Allergies

Overactive immune responses to non-harmful substances (hay fever is an example).

Natural passive immunity

Immunity passed from mother to baby (e.g., via breast milk) without the baby’s own immune response.

Natural active immunity

Immunity developed when the body produces antibodies after an infection.

Artificial passive immunity

Temporary immunity provided by doses of antibodies (serum) administered externally.

Artificial active immunity

Immunity induced by vaccination; the body develops its own immune response.