Bio 3 - Transportation of Substances around the Body - The effect of exercise on the body

Your muscles use a lot of energy. They move you about and help you support your body against gravity. Your heart is made of muscle, and the movement of food along your gut depends on muscles too

Muscle tissue is made up of protein fibres which contract when they are supplied with energy from respiration. Muscle fibres need a lot of energy to contract. They contain many mitochondria to supply the energy they need by aerobic respiration.

They also contain Glycogen stores. Glycogen is a carbohydrate which can be converted rapidly into Glucose. This supplies the fuel needed to provide the energy for cellular respiration when muscles contract (Glucose + Oxygen = Carbon Dioxide + Water + Energy)

Muscles fibres usually occur in big blocks or groups known as Muscles. Your muscles contract to cause movement. They relax when their job is done which allows others to work

Even when you're resting, your muscles use up a certain amount of oxygen and glucose. This is because some of your muscle fibres are constantly contracting to keep you in position against the pull of gravity. 

Muscles are also involved in your life processes such as breathing and circulation of the blood.

But when you begin to exercise, your muscles start contracting harder and faster. Because of this they need more Glucose and Oxygen to supply their energy needs. During exercise the muscles also produce increased amounts of CO2. This needs to be removed for them to keep working effectively

During exercise, when muscular activity increases, several changes take place in your body:

- Your heart rate increases and the arteries supplying blood to your muscles dilate. These changes increase the blood flow to your exercising muscles. This in turn increases the supply of oxygen and glucose and increases the removal of CO2

- Your breathing rate increases and you breathe more deeply. These changes mean that not only do you breathe more often, but you also bring in more air to your lungs every time you breathe. This increases the amount of oxygen brought into your body and picked up by your red blood cells. The oxygen is carried to the exercising muscles. It means that more CO2 can be removed from the blood in the lungs and breathed out

Your heart and lungs benefit from regular exercise. Both the heart and the lungs become larger. They both develop a bigger and very efficient blood supply. This means they function as effectively as possible at all time, whether you are exercising or not

More blood is pumped out of the heart during each beat, the hearts volume increases and your breathing and pulse rate decreases