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Role of energy in the body Essay

In our bodies we need energy we need energy for everything we do, move our muscles, talk etc. Without energy we wouldn’t be able to do anything, energy is needed for our bodies to function. Chemical reactions in our body extract energy from the food we eat. Doing everything to body needs to stay alive and grow includes, pumping ions across membranes, making hormones, making new cells, neural function, contracting muscles, replacing damaged or worn out components, absorbing nutrients, excreting wastes and pumping blood.

Supplying enough energy to support the many functions of the body at work is food. This energy comes from the fats, carbohydrates, and proteins in the food you eat. Of the three, fat is the most concentrated source of energy because it takes more than twice as much energy for a given weight as protein or carbohydrate. The energy requirement for a person is divided into two parts: basal metabolic requirements and energy required for activity. Basal metabolic rate is the heat eliminated from the body at rest when temperature is normal. An average person requires 2000-2400 Calories per day while a large man doing heavy work may require up to 6000 Calories per day. The three main classes of food provide the following amount of energy: carbohydrates and proteins provide about 4 Calories per gram; fats provide about 9 Calories per grams.


Hormones control the direction and rate of metabolism. The rate of metabolism when a person is at rest is called basal metabolic rate. It is the measure of heat produced by metabolism. The molecules of glucose and fatty acids are in the process of metabolism. When digestion takes place in the body, dietary proteins are split into amino acids, dietary fats into fatty acids and dietary carbohydrates into simple sugars such as glucose. The breaking up is caused by enzymes. The compounds produced by the process of splitting are absorbed by the body and transported by the blood to the cells. Anabolism-

Molecules combining to form complex compounds is the process in anabolism. Cells combine amino acids to form structural proteins and functional proteins. Structural proteins help repair and replace tissues. Enzymes, antibodies and hormones are functional proteins that respectively catalyze chemical reactions, help fight disease and regulate body processes. Cells convert glucose and fatty acids to energy storage compounds.


The breaking down of glucose, fatty acids and amino acids for energy and heat is the process called catabolism. The breaking down of fatty acids takes place into two steps.

The respiratory system consists of the nose, mouth, pharynx, larynx, trachea, bronchi and lungs. These allow air in and out of the body, every cell in the body requires oxygen to survive.

The primary function of the respiratory system is the exchange of gases. The respiratory system allows oxygen and carbon dioxide exchange. During the process of breathing air is inhaled and carbon dioxide is exhaled, this change of gases occurs in the alveoli. The inhaled oxygen passes into the alveoli and then diffuses into arterial blood. The waste rich blood from the veins releases carbon dioxide into the alveoli which is released through exhaling.

Air enters through nostrils which contain coarse hairs. The pharynx is shared between the digestive and respiratory system and extends between the nostrils and the larynx. The larynx joins the pharynx to the trachea; it consists of cartilages and is also known as the voice box. The trachea divides to form the primary bronchi, the left and right bronchi which the bronchi are two tubes that carry air into the lungs and they break down into smaller branches which are called bronchioles. At the end of these are air sacs called alveoli which absorb oxygen from the air. The diaphragm is a muscle which is directly below the lungs, during inhalation the diaphragm contracts to allow the chest cavity to expand as the lungs fill with air.

Journey through the respiratory system-

The air first enters through your nose or mouth and it is filtered by little hairs in your nose that stop dirt and dust getting in. The air then travels down the back of your throat and into your windpipe or trachea. Your trachea then divides into air passages called bronchial tubes. For the lungs to work their best these airways need to be open during inhalation and exhalation. As the bronchial tubes pass through the lungs they divide into smaller air passages called bronchioles; the bronchioles end in tiny air sacs called alveoli. The alveoli are surrounded by capillaries, oxygen inhaled from the air pass through the alveoli walls and into the blood. After absorbing the oxygen, blood leaves the lungs and goes to the heart, the heart then pumps it through the body to provide oxygen to organs and tissues.

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