The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7â8 ma.
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.
Pleural Membrane Function. The Pleural Cavity is filled with a small amount of serous fluid which forms a thin film of liquid between the pleural layers. This is vital in that it prevents separation of the two pleural layers and lubricates the surface, so the lungs can move easily within the thoracic cavity.ach lung is placed within a separate layer of membrane, thus there are two pleural sacs. The space between the two sacs is known as the mediastinum, and is almost in the midline of the thorax. The pleura covering the surface of the lung is known as pulmonary pleura or visceral pleura.