lymphatic & immune system

Lymph

Clear, colorless fluid that contributes to the formation of plasma (liquid portion of blood)

Structures of the lymphatic system

Includes ducts (vessels), lymph nodes (cervical, axillary, inguinal), thymus, right lymphatic duct, palatine tonsils, spleen, cisterna chyli, and thoracic duct

Functions of the lymphatic system

Acts as a drainage system, maintains fluid balance by collecting excess lymph from tissues and returning it to the bloodstream, and plays a key role in immune defense

First line of innate defense

Physical barriers such as skin, mucous membranes, mucus in the respiratory tract, vertebral column, spinal cord fluid, and meninges. Chemical deterrents include acidic vaginal secretions and tears

Second line of innate defense

Cell-derived defenses including phagocytosis, complement proteins, interferons, inflammation, and fever

Nonspecific immune cells

Includes phagocytes and macrophages (white blood cells) that attack pathogens without targeting specific ones

Clotting factors in immune defense

Activate at injury sites to block pathogen entry and help prevent infections

Proteins in immune defense

Aid in inflammation and activate phagocytes to fight infections

Normal flora

Natural microorganisms in the mouth, skin, and GI tract that outcompete harmful microbes, preventing infection

Specific (adaptive) immune defense

Specialized proteins and cells that target specific pathogens, including antibodies, complement proteins, and lymphocytes

Antibodies

Proteins that bind to pathogen surfaces to neutralize them or mark them for destruction

Complement system

A sequence of proteins that activate upon foreign substance exposure, destroying pathogens and enhancing antibody and inflammation effects

Lymphocytes

White blood cells originating in bone marrow from hematopoietic stem cells; include B-cells and T-cells; circulate in body fluids to detect pathogens