Crash Course :Lymphatic System

Lymphatic System

A one-way network of vessels and organs that returns interstitial fluid to blood and plays a key role in immunity

Interstitial Fluid

The fluid that leaks out of blood capillaries and bathes the cells of the tissues.

Lymph

The fluid inside lymphatic vessels; formerly interstitial fluid.

Lymphatic Capillaries

Blind-ended, permeable vessels that collect interstitial fluid from tissue spaces.

Lymphatic Vessels

Vessels that carry lymph; contain valves and rely on skeletal muscle action for flow.

Lymph Nodes

Small, bean-shaped organs that filter lymph and house lymphocytes (B cells and T cells).

Lymphocytes

White blood cells (B cells and T cells) that carry out the adaptive immune response.

Mucosa-Associated Lymphoid Tissue (MALT)

Lymphoid tissue located in mucous membranes; provides immune surveillance at body openings.

Tonsils

A ring of MALT in the pharynx; a first line of defense against inhaled or ingested pathogens.

Peyer's Patches

Clusters of MALT in the wall of the small intestine.

Skeletal Muscle Pump

The main mechanism for lymph movement, where contracting muscles squeeze lymphatic vessels.

Subclavian Veins

The veins where the thoracic duct and right lymphatic duct empty, returning lymph to the bloodstream.

Lymphedema

Swelling caused by a blockage in the lymphatic system that prevents proper drainage of interstitial fluid.

Thoracic Duct

The largest lymphatic vessel, which drains lymph from most of the body into the left subclavian vein.