Exercise and Respiration

• What happens to respiration when we star exercising?

  • Humans need energy for movement, to keep warm and to build larger molecules and ll of the energy we need is provided by respiration 
  • When we are relaxing, we do not need a great deal of energy because we are not moving  
  • But during exercise the body demands more energy for muscle contraction 
  • The body needs to react to this increased demand for energy 
  • So the rate of aerobic respiration increases , and this means that the body cells require more oxygen

  
• What happens in order to supply the body with more energy during exercise?

  • The breathing rate and breathing volume increase (In other words, we breath more frequently and take deeper breaths) , and this gets more oxygen into the bloodstream 
  • The heart rate also increases to pump oxygenated blood around the body  
  • These 2 factors supply the muscles with more oxygen and glucose during the increase in aerobic respiration when the muscles demand more energy 

  
• What happens if there is not enough oxygen during exercise?

  • Sometimes not enough oxygen can be supplied to the muscles , especially during intense exercise 
  • At this point anaerobic respiration will take place in the muscles 

  
• What causes the build up of lactic acid when anaerobic respiration takes place?

  • During anaerobic respiration, the oxidation of glucose is incomplete 
  • This leads to a buildup of lactic acid  
  • During long periods of vigorous activity , the lactic acid causes the muscles to hurt and become fatigued , and this stops them from contracting efficiently 
  • Lactic acid is a poison , so the body has to remove it from the body quickly 
  • This creates a condition called oxygen debt

  
• How is lactic acid removed from the body?

  • The lactic acid is transported out of the muscles by the blood 
  • The lactic acid is then taken to the liver and is converted back to glucose in a series of chemical reactions
• What is oxygen debt?

  • Reacting with the accumulated lactic acid and removing it from the cells require oxygen 
  • So the oxygen debt is the amount of extra oxygen the body needs after exercise to deal with the accumulated lactic acid
• Oxygen debt is the reason that people continue breathing rapidly after finishing exercise - to gain enough oxygen to get rid of the lactic acid