Emphysema is a disease of the lungs. Explain why people suffering from this condition may feel weak and short of breath.(6 marks)

Emphysema is an obstructive lung disease(1), where alveoli collapse due to break down of elastin in their walls(2). This means that the lungs cannot recoil(3), making expiration difficult. There is less surface area and increased diffusion distance(4), thus reducing the diffusion gradient so less air leaves the lungs and less oxygen enters the blood(5). Therefore, a  person suffering from emphysema may feel weak and short of breath as they're taking in less oxygen into their tissues so less ATP/energy is produced(6).