A strong emphasis is placed in the parcelling out and multicellular state of the vital body functions that resulted in the interdependence of the different body cells. Keep in mind that the organ-systems do not work in isolation because a smooth collaboration is needed in order to promote well-being of the human body.
Most of the nutrients came from the food we ingest. The nutrients and chemical substances are used by the body for energy building, body repair and cell building.
The nutrients we receive are dependent on the type of diet we have. Plant-derived foods are extremely rich in vitamins, minerals and carbohydrates. On the other hand, animal foods are richer in content when talking about proteins and fats.
The major energy fuel for our body cells is carbohydrates. Proteins, with the help of fats to a lesser degree, contribute to cell structure building. In the event when the supply of carbohydrates is not sufficient, the body makes use of fats as a reserve for energy-rich fuels. In order for chemical reactions to occur smoothly in the cells, certain minerals and vitamins are required to suppliant the demand of the cells. An example of this is the mineral calcium which is vital in making the bones harder and is also involved in blood clotting.
No matter how abundant the supply of nutrient is, it will all go to waste when oxygen is not present. The chemical reactions that release the much needed energy from the food we eat are oxidative reactions. Oxidative reactions need oxygen in order to function effectively, thus the reason why human beings are only able to survive a few minutes without oxygen. Of the air we breathe, 20% is oxygen. With the collaborative effort of the cardiovascular and respiratory systems, oxygen is made available and distributed to the body cells via the blood.
Accounting for almost 80% of the body weight, water is the single most abundant chemical substance found in the body. Obtained chiefly from ingested foods and liquid, water provides the environment that is necessary for chemical reactions to occur. Excretions and secretions of fluids by the body are also based on the liquid found within the body.
Maintenance of normal body temperature is needed for the sustenance of chemical reactions that continue at life-sustaining rates. Body temperatures have a direct impact on the metabolic reactions of the body. When to temperature of the body drops below 37 degrees Celsius, the metabolic reactions become slower and when it continues to drop, it then comes to a complete halt. Conversely, when body temperatures become too high, chemical reactions occur at an erratic and frantic pace. The body proteins become confuse and lose their distinct shape. As the proteins lose their shape, they are unable to perform their required function and then come to a complete stop. Whether the temperature goes up and goes down, death occurs at its extreme.
Atmospheric Pressure Credit: http://www.randomscience.com/general/drinking-straw-is-an-application-of-atmospheric-pressure/
Although at first glance this may seem too farfetched, but atmospheric pressure has a vital link to the body. Our ability to breathe and perform gas exchange in the lungs is dependent on the appropriate atmospheric pressures.
You may have noticed that on higher grounds it is harder to breath compared to when you are on a lower ground. This is because the air is thin and the atmospheric pressure is lower.
Although it is indeed important for these survival factors to be present, their presence alone is not satisfactory to sustain life. Remember that they must be available in appropriate amounts in order to take effect the ultimate goal of all body systems, which is the ability to maintain life.