Question

What happens to the rubber sheet and the balloons when the string is pulled downwards?

Answer 1

The physical movements associated with the gaseous exchange are called breathing. They are controlled by the respiratory centre of the medulla oblongata in the human brain. Thus, the breathing movements are involuntary to a large extent. However, we can control the rate of breathing and the extent of breathing but not for a long time. The respiratory centre is stimulated by the carbon dioxide concentration of the blood.