Lumen (anatomy)

In anatomy, a lumen (plural: lumina) refers to the inside space of a tubular structure, such as an artery, vein, intestine, gland, or renal tubule. It is the channel within a tube-like organ. The lumen is the space through which substances pass, such as blood, digestive contents, secretions, or urine.

The shape and size of the lumen can vary depending on the specific organ and its physiological state. For example, the lumen of a blood vessel can constrict or dilate to regulate blood flow. Similarly, the lumen of the intestines can expand to accommodate a bolus of food.

Understanding the structure and function of the lumen is crucial in comprehending the overall physiology of the organ it belongs to. Obstruction or narrowing of the lumen can lead to various diseases, depending on the affected organ. For instance, atherosclerosis can narrow the lumen of arteries, leading to reduced blood flow.