Energy is the capacity of a physical system to perform work. Energy exists in several forms such as chemical, electrical, heat, sound, light and mechanical. http://physics.about.com/od/glossary/g/energy.htm Energy can be defined in a variety of different ways. However, the most common way to define energy is ‘the ability to work’. All living organisms need energy to survive, all the basic functions of a human to survive need energy, to maintain them from not stopping. e.g. breathing, the heart beating, moving etc.
The whole body needs energy, otherwise it wouldn’t work, and we get our energy from eating foods and drinking. The food and drink goes into our stomach and from there it is digested, absorbed, then either stored or converted into energy by chemical reactions in our body, therefore food is chemical energy. https://uk.answers.yahoo.com/question Glucose + Oxygen = Carbon Dioxide + Water + Energy
In other words, glucose and oxygen are turned into carbon dioxide and water releasing energy. http://purchon.com/chemistry/?page_id=223 The sum of all chemical reactions within a living organism is known as metabolism.
The two body systems I am going to explain in detail are Respiratory and Circulatory and their role in producing energy:
Respiration
Respiration involves breathing. External respiration which is also known as breathing refers to the inhalation of oxygen from the air into the lungs and expelling carbon dioxide from the lungs to the air. External respiration is a physical process during which oxygen is taken up by capillaries of lung alveoli and carbon dioxide is released from blood. Respiration occurs through our mouth, nose, trachea, lungs and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx, and the trachea. In the chest cavity, the trachea