Indicate whether the following events would increase or decrease alveolar compli
ID: 96498 • Letter: I
Question
Indicate whether the following events would increase or decrease alveolar compliance. In the space below the answer line, briefly explain how this condition affects compliance in the manner indicated.
Decreased surfactant:: _________________________
Explanation:
Pulmonary edema: ______________________________
Explanation:
Loss of elastin (as seen in emphysema): __________________________
Explanation:
Pulmonary fibrosis (scarring around alveoli): ____________________________
Explanation:
Explanation / Answer
Alveolar Compliance/ Lung Compliance/ Pulmonary Compliance is defined a change in lung volume per unit change in airway pressure.
Explanation:- Surfactantisanagentthatdecreasesthesurfacetensionbetweentwomedia.The surface tension between gaseous-aqueousinterphaseinthelungs (alveolar surface tension)isdecreasedbythepresenceofathinlayeroffluidknownaspulmonarysurfactant. It is a complex mixture of lipids and proteins secreted by Type II alveolar cell. It intersperses between the water molecules in the fluid lining the alveoli, therefore, lowers the surface tension and increases alveolar compliance. Decrease in surfactant causes increase in the alveolar surface tension and thus subsequent decrease in alveolar compliance.
Explanation:- In case of pulmonary oedema, oedematous fluid, occupy the alveolar spaces. Thus the volume of air at total lung capacity decreases. The oedematous fluid in the alveolar spaces washes away surfactant, (the complex phospholipid that reduces surface tension at the air and alveolar wall interface) causing increase in surface tension. This results in decreased alveolar compliance.
Explanation:- Connective tissue in lungs contains lot of elastin fibres surrounding the alveolus. This elastin is responsible for expansion and elastic recoil of lung. Elastic recoil refers to how quickly the lungs rebound [come back to normal] after they have been stretched. Loss of elastin decreases the elasctic recoil. Therefore, compliance of the lung in emphysema is significantly above normal. This is because in emphysema (loss of elastin), the lung can easily distend but cannot be emptied efficiently. Emptying of lungs occur slowly.
Explanation:-Compliance refers to the distension capacity of lungs is defined a change in lung volume per unit change in airway pressure. In fibrosis the lungs become stiff, making a large pressure necessary to maintain a moderate volume. Thus the compliance of the lungs decreases