The innermost layer of the serous membrane surrounding
the lungs is called the __ pleura.
The outermost layer of the serous membrane surrounding
the heart is called the __
pericardium.
The correct answer and explanation is:
Correct Answers:
- The innermost layer of the serous membrane surrounding the lungs is called the visceral pleura.
- The outermost layer of the serous membrane surrounding the heart is called the fibrous pericardium.
Explanation:
Visceral Pleura:
The lungs are surrounded by a serous membrane known as the pleura, which is divided into two layers: the visceral pleura and the parietal pleura. The visceral pleura is the innermost layer that directly adheres to the surface of the lungs, following their contours and fissures. This layer ensures a smooth interface between the lungs and the surrounding structures, reducing friction during respiratory movements. The pleura also produces a small amount of serous fluid, which resides in the pleural cavity (the space between the visceral and parietal pleura) to facilitate smooth lung expansion and contraction. The visceral pleura is richly innervated by autonomic nerves and receives blood supply from the bronchial arteries, distinguishing it from the parietal pleura, which lines the thoracic cavity.
Fibrous Pericardium:
The heart is enclosed within a double-layered sac called the pericardium, which consists of an outer fibrous pericardium and an inner serous pericardium. The fibrous pericardium is the tough, outermost layer composed of dense connective tissue. It protects the heart, anchors it to surrounding structures (like the diaphragm and great vessels), and prevents overdistension of the heart during periods of increased blood volume. Beneath the fibrous pericardium lies the serous pericardium, which is further divided into the parietal and visceral layers. The fibrous pericardium works in conjunction with the inner serous layers to ensure that the heart can beat efficiently without excessive movement or friction, maintaining cardiovascular stability.
Both membranes play crucial roles in protecting their respective organs and ensuring efficient physiological function during respiration and circulation.