<span>Pleural sac is a two
layered membrane formed when a serous membrane known as pleura folds back onto
itself. Thus, the pleura invest the lungs and line the walls of the thoracic
cavity. However, the potential volume of the thoracic cavity increases during
inhalation.</span>
osmosis and diffusion are both passive transport bc it doesnt require energy and only moves down cocentration gradient, never against concertration gradient. Give me a brainliest if i helped! ♡
