serous membrane
Meaning of serous membrane: A serous membrane lines internal body cavities and covers the organs within them, secreting fluid that reduces friction during movement.
Definition of serous membrane
A serous membrane is a thin membrane that lines the walls of certain body cavities and folds back to cover the surface of the organs contained within them. Serous membranes are found in the chest, where they form the pleura surrounding the lungs and the pericardium surrounding the heart, and in the abdomen, where the peritoneum lines the abdominal cavity and covers organs such as the stomach and intestines.
Each serous membrane consists of two layers, an outer layer attached to the cavity wall and an inner layer attached to the organ's surface, with a thin, fluid filled space between them. The membrane secretes a small amount of watery fluid into this space, allowing the two layers to glide smoothly against one another as organs move, expand, or contract.
Because a serous membrane forms a closed space around the organ it surrounds, conditions that increase fluid within that space, or that inflame the membrane itself, can affect the organ's normal movement and function.
Also known as
Used in a sentence
Imaging showed thickening of the serous membrane surrounding the affected organ.
Good to know
A serous membrane's two layers are normally separated only by a thin film of fluid, so a noticeable increase in fluid within that space, however it is named for a particular organ, reflects the same general process occurring in a different location.
Word origin
Where “serous membrane” comes from
Formed from Latin serum, meaning whey or watery fluid, describing the thin lubricating fluid these membranes produce.