The biological importance of water

Water is the most important element in the world and is necessary for the existence of life on earth. Life began in water, many living organisms live in water and some organisms are made up almost entirely of water (E.g-Jellyfish-93% water). Water chemically has a basic structure of two hydrogen atoms and one oxygen atom (H�O).

They are bonded together covalently, sharing electrons to form water. Water is made of particles, which have polarity but remain stable due to the hydrogen bonds they form; the bonds are formed because of the opposite charges between oxygen and hydrogen. All chemical reactions in organisms take place in water; it is used in hydrolysis to break up bonds (E.g.-The breakdown of proteins down to amino acids). Osmosis and diffusion are transport mechanisms, which use water for things such as in the lungs during gaseous exchange and in plants when water is consumed. Water is extremely important biologically within plants as with humans, but especially with plants due to it being a fundamental reactant in photosynthesis (A plants life process).




Water is also used as a solvent in tissue fluid (Lymph) and as the transport fluid in blood carrying Red Blood Cells, White Blood Cells, Platelets and Plasma. Water is used to aid the removal of waste in humans in a solution along with urea and ammonia. In the human body water is key to temperature regulation, when the body becomes too hot it sweats and water is evaporated to cool the body. Basic functions like body temperature, hearing and balance are key to our survival and they would not be possible without water.

Thermal Properties of Water

* High Boiling Point due to strength of Hydrogen bonds.

* Water is good at absorbing heat.

* Water will buffer high temperatures.

* Water will insulate heat.

Water is at its most dense at just above 4�C because as its temperature increases it begins to evaporate and the particles begin to spread out. Below 4�C hydrogen bonds form and the water begins to solidify into ice, e.g. colloid (solid suspended in a liquid).

Water is commonly the base for secretions (E.g.-Digestive juices, tears, snake venom, etc). COLLOID =

Water is a lubricant for many different parts of the human body and there are several different types of water lubricants:

1. Mucus-found in earthworms, human gut wall and vagina.

2. Synovial fluid-lubricates joints such as knee.

3. Pleural fluid-This lubricates the lungs (As above), lines them and provides effusion fluid.

4. Pericardial fluid-Gives lubrication to the heart only.

5. Periviscerial fluid-This water-based lubricant lines key organs.

In the human body biologically water is extremely important not only to transport, cool and be digested but also to support other functions in the body. Water can provide large cohesive forces for example an earthworm has a hydrostatic skeleton which is supported heavily and solely by water.

Water controls the turgidity of cells and the amount of turgor pressure produced.

Water supports the humours of the eye (Aqueous and Vitreous Humour) and during female pregnancy water-based amniotic fluid/sac supports and protects the mammalian foetus. Water supports the blood flow to the penis when it becomes erect; this is imperative for reproduction and shows how important water can be in life.

Water is used in metabolic reactions to anabolic ally or catabolically alter cells. Anabolic reactions (building up of compounds in cells) using water require energy whereas catabolic reactions (breaking down of cell compounds) result in a release of energy.

In conclusion water from a biological point of view is imperative to the survival of all living organisms on earth. I have expressed the significance of water in the human body and briefly in plants and it is clear that without water nothing could live. Water transports, supports, thermally regulates and is a living environment to some sea mammals. Water is so essential and important that a human being can supposedly survive on water alone for 44 days and 44 nights (David Blaine) without food!!