Blood Circulation
Heart disease    The effects of exercise

Our heart is a pump. It pumps blood around the body.

Blood is very important to us as it carries important substances like food and oxygen around the body.

Actually the heart is two pumps.
The right hand side of the heart pumps blood up to the lungs where it absorbs oxygen.
This blood is low in oxygen and is shown blue in the diagram.
The left side of the heart now pumps the oxygen rich blood (shows red in the diagram) to all other parts of the body where it gives up its oxygen to the cells.

 Blood circulaThe science site blood circulationtion Blood Circulation
simplified diagramRed = blood rich in oxygen
Blue = blood low in oxygen

blood Ciculation


Put oxygen into the blood and remove carbon dioxide

Pumps blood around the body.
The heart consists of TWO pumps (shown red and blue)
The heart contains valves to control the direction of blood flow.

Arteries   Blood vessels that carries blood away from the heart

Veins       Carry blood back towards the heart.

Tiny blood vessels that carry blood to the individual cells.
Capillaries join the arteries to the veins.



  • i) Transports oxygen to the cells (carried out by the red blood cells)
  • ii) Transports waste away from the cells.
  • iii)Helps protect the body from infection  (carried out by the white blood cells)
  • iv) Helps regulate the body temperature (keeps us at 37º C)

What is in blood

  • Red blood cells:   Contain haemoglobin to carry oxygen.
  • White blood cells  Fight disease
  • Platelets:  Cells that help the blood clot
  • Blood plasma: the liquid part of the blood.
    Blood plasma is a pale yellow liquid and contains dissolved food along with other dissolved substances.


Heart disease
Heart disease can be caused by too much fat which clogs the arteries reducing the flow of blood to the heart. Exercise helps reduce the risk by speeding the flow up blood up which helps clear the arteries.

How to help reduce the risk of heart disease:

Take regular exercise

Eat a balanced diet that is low in fatty foods Don’t smoke (smoking can damage the arteries) Avoid too much alcohol

The effects of exercise on the body
When we take some form of exercise, e.g. running 400m, our muscles move more and so need more food and oxygen from the blood.
This causes the following changes to take place in our body:

  • Our heart pumps faster so more food and oxygen reaches the muscles.
  • We breath faster to put more oxygen into the blood.
  • We sweat to cool us down.

Investigating the effect of exercise on blood circulation The aim of this investigation is to see how various areas of the body, in particular the heart, are affected by heavy exercise.   We first measured the heart rate (pulse) while resting in the class room. We then carried out 5 minutes of vigorous exercise and then measured the heart rate again at 5 minute intervals until the rate dropped back down to normal.


Heart Rate in beats per minute (b.p.m)
While resting  80
Immediately after 5 minutes exercise  190
5 minutes after the exercise  130
10 minutes after the exercise  100
15 minutes after the exercise  81

The pulse was either taken at the wrist  (where an artery is near the surface of the body) or the side of the neck just beside the windpipe (trachea).  
Our results showed us that the heart rate increased rapidly after exercise and then gradually dropped back to normal. This happened because the muscle cells needed more sugar and oxygen. The time taken  for the pulse to drop back to normal is called the recovery period.
The sugar and oxygen initially came from the chemicals already in the blood and muscle cells but as they ran out we started to breath faster to replace the oxygen being used up.   We started to sweat to remove the heat energy being generated by the muscles.