The human body uses food as an energy source to carry out various tasks. Our bodies can use a number of foods to produce energy, but the main source of fuel is sugars such as glucose. The process of using oxygen and glucose to produce energy is known as respiration.
Respiration is the process the body uses to convert glucose to energy. It occurs in every living cell within the body, and the simplified formula is:
Glucose + Oxygen produces Energy + Carbon dioxide + Water
Respiration is the reason we breath in oxygen and breath out carbon dioxide.
One of the defining features of animals is the ability to move and manipulate the environment. This is due to muscular tissue. Muscle consists of millions of fibres, which when contracted produce movement. The process of muscular contraction uses large amounts of energy and is responsible for the heart beating (the heart is a muscle), breathing, and skeletal movement.
The body has many chemical processes going on at any one time. These chemical processes are carried out by biological catalysts known as enzymes. Enzymes can only help a chemical reaction take place if they are at a specific temperature. The body regulates temperature to keep enzymes working. This temperature regulation uses energy. An example is sweating. When the body becomes too hot, energy is used to secrete sweat from glands on the skin, cooling the body.
The human body largely consists of water, which has to be regulated to ensure cells don`t shrivel up or rupture. The regulation of water is performed by a hormone known as anti-diuretic hormone (ADH). When water levels in the body become too high, the hypothalamus gland detects this and secretes ADH. The ADH stimulates the kidneys to absorb more water, which eventually gets excreted from the body. The synthesis of ADH, the functioning of the kidneys and the excretion of urine all require energy.