Q.A fluid filled double membranous layer surrounds the lungs. Name it and mention its important function.

The fluid-filled double membranous layer surrounding each lung is the pleura, made of an outer pleural membrane lying against the thoracic wall lining and an inner pleural membrane clinging to the lung surface, with pleural fluid filling the gap between them. Its important function is to reduce friction against the lung surface as the lung moves du …

Each of the two lungs is wrapped in a double-layered pleura, with pleural fluid occupying the gap between the two membranes. The outer pleural membrane lies against the lining of the thoracic wall, while the inner pleural membrane clings closely to the surface of the lung itself. …

Method: Naming an anatomical covering and stating its function

This method applies to any question that asks you to identify a protective/covering membrane around an organ from a description, and then explain why it exists.

Steps

Step 1: Locate the organ system from the clue

The question describes a structure by its position and physical property (fluid-filled, double-layered, surrounds an organ) rather than naming it directly. First identify which organ system the clue points to — here, "surrounds the lungs" places it squarely in the respiratory system.

Step 2: Recall the general pattern of serous membranes

Many internal organs that move or expand (lungs, heart, abdominal organs) are wrapped in a double-layered membrane with fluid between the layers — an outer layer anchored to the body-cavity wall and an inner layer stuck to the organ's own surface. Recognising this recurring two-layer-plus-fluid pattern lets you predict the general structure even before naming the specific membrane (pleura for lungs, pericardium for heart, peritoneum for abdominal organs).

Step 3: Derive the function from the structure, not just from memory …