Principles of human body functioning Essay

1.0 INTRODUCTION
Human body is like a highly technical and sophisticated machine. It operates as a single entity but is made up of a number of systems that work interdependently. Each system is associated with specific function that is essential for the well-being of human. If one system fails, the consequences are likely to extend to other systems, and reduce the ability of the body to function normally. Integrated working of the body systems ensure the ability of human to survive. Cells are the smallest independent units of living matter and there are trillions of them within the body. Each cell are specialised and carries out a particular function that contributes to the body need. Cells with similar structures and functions are found together forming tissues. Organs are made up of a number of different types of tissue and evolved to carry out a specific function. Systems consist of a number of organs and tissues that together contributes to survival needs of the body.
External environment surrounds the body and provides oxygen and nutrients required by body cells. Waste products from cellular activity are eventually excreted into the external environment. Internal environment is the water-base medium in which body cells exist. Cells are bathed in interstitial fluid. Oxygen and other substances need to pass from the internal transport system through the interstitial fluid to reach cells. Each cells is surrounded by plasma membrane which provides a potential barrier to substances entering and leaving the cell. The chemical composition of the fluid inside and outside the cell are different. The composition of the internal environment is tightly controlled and this constant state is called homeostatis.
2.0 HOMEOSTATIS
Many factors affect the stability of body cells to sustain life. This include oxygen and carbon dioxide concentrations, the pH of the internal environment, concentrations of nutrients and waste products, concentration of salt and other electrolytes, volume and pressure of extracellular fluid, body temperature and blood glucose level. As these properties affect the chemical reactions, there are built-in physiological mechanisms to maintain it at desirable levels. The body needs homeostasis to maintain stability and survive by ensuring that the internal environment remains relatively constant (Tortora and Anagnostakos, 2003). To enable cells to survive, the composition of the intracellular and extracellular fluids must be accurately maintained at all times. Intracellular fluid accounts for two-thirds of total water content (Tortora and Anagnostakos, 2003). Extracellular fluid includes gases, nutrients, plasma and ions which are necessary for maintaining life. (Tortora and Anagnostakos, 2003).
The body is said to be in homeostasis when its internal environment contains optimum levels of gases, ions, water and nutrients, optimal temperature and pressure for the health of cells. The endocrine and central nervous systems are the major control systems for regulating homeostasis (Tortora and Anagnostakos, 2003) . The endocrine system consists of a series of glands that secrete chemical regulators (hormones). The nervous system can detect deviation from the body's normal equilibrium (state of homeostasis) and sends messages to the affected organ to counteract this