Breathing

BREATHING
  •    Exchange of gases or taking in O₂ and giving out CO₂ with the help of respiratory organs is called breathing. 
  •    The taking in of air rich in oxygen is called inhalation and giving out CO₂ rich air is called exhalation. 
  •    It is a continuous process which goes on all the time and throughout the life of an organism.
  •    The number of times a person breathes in a minute is called the breathing rate. 
  •    Normal breathing of adult human beings at rest is about 15-18 per min. But it can change according to requirement of O₂ by the body. 
  •    Thus, whenever a person needs extra energy breathing rate increases. 
  •    So, during heavy exercise, the breathing rate can increase upto 25 times per minute and also we take deep breaths to inhale more oxygen. 
  •    As a result more oxygen is supplied to our cells. 
  •    So speeds up the breakdown of food and more energy is released. 
  •    That is the cause we feel hungry after a physical activity.