B2- AQA GCSE Biology-Respiration

Exercise and Respiration

• During exercise, the body demands more energy, so the rate of respiration need to increase
• The heart rate , breathing volume all increase to suply the muscles with more oxygen and glucose for the increase in aerobic respiration
• During periods of vigorous activity, the muscles may not get supplied with enough oxygen, so anaerobic respiration starts to take place in muscle cells
• This causes a build up of lactic acid and creates an oxygen debt
• The lactic acid causes the muscles to hurt and stops them contracting efficiently. Lactic acid is a poison, so needs to be got rid of quickly. 
• Once exercise is finished the oxygen debt must be repaid 
• After exercise, blood flowing through the muscles transports the lactic acid to the liver where it is broken down
• Ther oxygen debt is the amount of extra oxygen the body needs after exercise to react with the lactic acid and remove it from the cells 

Anaerobic Respiration-  is when the muscles are working very hard and the circulation cannot deliver enough oxygen for all the energy needed to come from aerobic respiration. The extra energy comes from an alternative process -anaerobic respiration- in which glucose is broken down to lactic acid, releasing energy.

Glucose ---> Lactic Acid+Energy

• Anaerobic respiration occurs to give you a boost of energy by using glucose
• After exercise, the lactic acid is either converted back to glucose or broken down to oxygen

Lactic Acid+Oxygen ---> Carbon Dioxide+Water

The feeling of burning and pain in the muscles during vigorous activity may be caused by high levels of lactic acid and other metabolities.

Aerobic Respiration- is respiration used in the presence of oxygen 

• Every life process needs ENERGY.
  
• Respiration is the process our bodies use to produce this energy.

Glucose+Oxygen  ---> Water+Carbon Dioxide+Energy

The glucose we need comes from food and the oxygen from breathing. Water and Carbon Dioxide are breathed out. The MAIN product of this equation is energy.

The energy produced in aerobic respiration is used to help the muscles work, to keep warm and to keep the heart beating. Also the energy helps with digestion. 

• Most of the reactions involved in aerobic respiration takes place in the mitochondria.
• Glucose and oxygen get to the respiring blood cells through the blood.
• Energy from respiration is used to enable muscles to move. Aerobic respiration is a very quick way of producing energy.

Water produced in aerobic respiration is lost from the body by :

• Sweat
• Tears
• Saliva

EXAMPLE:

Runner can manage a sprint finish at the end of a race because the extra energy comes from the remaining glucose NOT oxygen. However a marathon sprinter cannot sprint for an entire race because they use up most of the energy from anaerobic respiration so they gain more energy from aerobic respiration.

The importance of Respiration

• Respiration is an example of an exothermic reaction
• It releases energy from glucose molecules for use by the body
• Organisms need this energy:

    -For chemical reactions to build larger molecules

   -For movement 

   -To keep warm 

• Respiration in cells can be aerobic (with oxygen) or anaerobic (without oxygen)