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Respiration and exercise

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When we exercise, our       When we exercise our

                                                                              respiratory system works

                                                                              at faster rates.

                                                                                 Respiration is the

                                                                              process where the air

                                                                              enters the body via the

                                                                              mouth or nostrils, and

                                                                              eventually ends up in

                                                                              our bloodstream.

                                                                                 The rest of the

 C                                                                          content of this document

                                                                              will explain this process

                                                                              in detail, as well as

                                                                              the circulatory system.


Circulatory System

As blood begins to circulate it leaves the heart from the left ventricle and enters the aorta. The aorta is the largest artery in the body, filled with oxygen. Arteries always take blood away from the heart, regardless of their oxygenation, and veins always carry blood back to the heart, also regardless of the blood’s oxygenation.

   In pulmonary vessels the blood oxygenation is reversed; the pulmonary artery takes deoxygenated blood to the lungs and oxygen is pumped into the pulmonary vein, which carries blood back to the heart.

   The four vessels that lead to the heart are the: Pulmonary artery, which takes blood to the brain and lungs. The Pulmonary vein, which carries blood back from the lungs, the Aorta, which takes blood around the body to capillary cells, and the Vena Cava that carries blood back from the body. As blood circulates round the body, nutrients and oxygen diffuse from the haemoglobin into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells. The body uses the nutrients and oxygen and turns it into energy.

   The biggest part in circulation is the heart. The heart is a muscle, which is constantly pumping oxygenated blood around the body via the arteries, and constantly receiving deoxygenated blood again from veins.

Respiratory System

For our bodies to sustain living we need energy. One of the bodies’ main sources of this is oxygen. We get oxygen from a process called respiration. In this process we breathe in air via the mouth or nostrils, the air then travels down the trachea. Once at the bottom of the trachea, some of the air will travel down the left bronchus, and some will travel down the right bronchus. Then the air will travel down many different bronchiole tubes. Once the air has gotten to the end of these tubes it will go into the alveoli.


Once in the alveoli the air will pass through the walls and nutrients and oxygen attach to the haemoglobin in the red blood cells. The blood cells will then diffuse from the oxygen and nutrients into capillary cells, as it circulates. On the blood’s way back round the body it releases the excess waste that was produced shown in the diagram above. This waste goes back through the Alveoli and is breathed out via the mouth or nostrils.

   When the oxygenated blood flows to the capillary cells the oxygen passes through the wall and goes to it’s designated area i.e. a muscle or the brain. This fuels the body as a form of energy. To make energy we need oxygen and glucose they combine to make this formula:

Oxygen + glucose  = carbon dioxide, water, Energy

O2  + C6 H12 O6 = CO2, H2O, Energy

 Inhalation is initiated by the diaphragm. When the diaphragm contracts, the ribcage expands. When we exhale it’s generally a passive process and the lungs recoil from the stretch of inhalation.

When We Exercise

When we exercise, our circulatory system, respiratory system and heart, work at a faster pace. This is to supply our muscles and organs with enough energy to carry on exerting the amount of energy that you’re doing.

   Because of this it means that we breathe faster, and have a faster circulation to get energy to the area of our body which is being exerted.


As shown in the diagram above, when we exercise exactly the same process occurs, but at a faster pace. The diagram displays the gas exchange of oxygen and other nutrients from the blood cells, being transferred to the body tissue in exchange for mainly carbon dioxide.

   When we don’t get sufficient energy for the exercise we are doing, then we use a back up energy stored near muscles called glycogen. This is mainly only for when the body can’t get sufficient energy from the air and has to be paid back after the exercise.

   If you still continue after all of the glycogen has run out, then your body starts using itself for energy and eating away at its own muscles.

This student written piece of work is one of many that can be found in our GCSE Humans as Organisms section.

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