Common Substances in Living Systems
Water is the most abundant substance in living cells; approximately 60% to 80%. Water molecules are polar, it determines why ionic bonded molecules dissociate in water. Hydrolysis is when water breaks down larger molecules of food during digestion. Water is considered to be a universal solvent. Water is also important for the transport of materials like hormones and enzymes within the blood plasma. Water helps to stabilize body temperature because it absorbs and releases high levels of heat before its temperature changes. Water serves as a shock absorber and finally it is a base for all body lubricants in system, The ammonia molecule (NHȝ) comes from the decomposition of proteins during digestion and the conversion of amino acids in the cellular respiration process. Nitrogen is an essential element in amino acids, which are the building blocks of proteins. Ammonia is toxic to cells, so it is converted to urea in the liver, and then filtered in the kidneys to be excreted as urine. Another common substance is mineral salts. Mineral salts are composed of small ions. They function in numerous ways as parts of enzymes or portions of the cellular environment. The following ions are necessary for nervous transmission: calcium (Ca+), sodium (Na+), potassium (K+) and chloride (Cl-).
Rizzo, D. C (2010) Fundamentals of Anatomy & Physiology, Third Edition
Homeostasis is a process that tries to keep (STASIS) things at a constant, steady, or the same (HOMEO) condition. It is the body’s attempt to maintain a constant internal environment. Maintaining a stable internal environment requires constant monitoring and adjustments as conditions change. Homeostasis is essential to survival, when it is maintained, the body is healthy. Examples of homeostasis in the body includes body temperature, blood sugar levels, heart rate, and the fluid environment of the cell The...