CHAPTER 2
Your Body of Water
PART 1
On Earth As In Your Body: The Functions of Water
Two atoms of hydrogen attached to one atom of oxygen; a chemical triad as familiar as air. Yet, the properties water possesses in the physical world, which are as fantastic as they are simple, are central to how the element functions within our bodies. READ MORE
Like the shapes that waves and ripples take on the ocean surface, the forms and functions of water in the body are innumerable. As described in Part 2, the characteristics of water evident to a physicist or chemist provide some understanding of how water keeps us alive.
The Super Solvent
Water dissolves more substances than any other liquid, including lethally corrosive agents such as sulfuric acid. Of course, pure water is neither acidic nor basic, but definitively neutral with a pH of 7.
In the body, water’s power to dissolve vitamins, minerals, sugars, and other nutrients lends it a critical role in nutrition and metabolism. Once dissolved, molecules can permeate cell membranes and go about their biological business. However, even though water is referred to as the “universal solvent,” not every nutrient is water-soluble. At times this is advantageous as well.
Thermostat
Due to water’s efficiency at absorbing and holding heat, the temperatures of oceans, rivers, and lakes are not subject to sudden swings in temperature, which would be deadly to aquatic life and chaotic for the atmosphere. The thermostability of water has long been harnessed by man for industry in cooling down the axle of a friction-heated wagon wheel or in maintaining the warmth of a radiator.
The same characteristic helps the body hold to a steady internal temperature, though that’s just one of several thermostatic functions of water in our biology. Water helps regulate temperature system-wide while functioning more discretely to adjust the heat up or down as required by specific organs.
Transport
The combined traits of solubility and “stickiness” (see Part 2) make water an ideal vehicle for transporting dissolved substances, or solutes. In nature, minerals are dissolved from rocks and soil and then travel in a stream, samples of which would be described as "hard" given the presence of mineral solutes.
Similarly, the minerals and other nutrients we ingest in food are broken down by water and then carried along in the bloodstream. Water helps carry excess nutrients and waste out of the body through urine in a similar manner. LESS
PART 2
Water Qualities
AbsorbableRain can transform an arid basin into waterlands. It breathes life into withered plants and replenishes food sources for animals. Precipitation also replenishes the groundwater that nourishes plant roots, and provides a layer of earth that is permanently soaked (the water table). READ MORE
Absorption of water heals and protects our bodies inside and out. Humidity helps moisturize the skin, and inhaled water molecules soothe and coat the mucosal linings of our noses, throats, and lungs. Every organ and nearly every cell in the body is thirsty for water and functions to its full potential only when well-hydrated.
“Sticky”
With a positive charge where the two hydrogen atoms attach to the oxygen atom and a negative charge at the opposite pole, H20 molecules are attracted to one another and bond easily. That’s why all the water stays together in your glass, and pools even when it spills. If you’ve ever noticed the tiny “dents” in a lake’s surface where it supports the legs of a water bug, or glimpsed how water momentarily flattens out around a belly-flopper in a swimming pool, you’ve witnessed hydrogen bonding at work. The cohesiveness of water molecules lends a stretchable, elastic quality to the water’s surface (known as surface tension).
Sometimes characterized as the “sticky” effect of water, hydrogen bonding is a component of water pressure. Unless acted upon by an outside force stronger than their own bond (think of a kid’s foot stomping into a puddle), water molecules stay together whether flowing freely or compressed in a narrow channel. Pressure increases with either an increase of water volume or a narrowing of the channel through which it passes.
In the body, an increase in blood pressure results from arteries narrowed by cholesterol buildup. Providing and sustaining the pressure of various fluids and tissues is a crucial though easily overlooked function of water within the body, affecting a huge range of processes from muscle movement to bile release to the filtering of excess nutrients.
Universal
Everywhere in the world, water is the basis of life. Whether underground, in the leaves, in the air, or in the clouds, the element is always multifunctional. Cycling between clouds and the Earth’s surface, it constantly changes state between liquid and gas, and assumes a solid, icy state in colder climates. Water is forever interacting, changing, and moving around our planet.
Water is ubiquitous in the body as well, and has the unique trait of being both innocuous and critical at every site. Extremely adaptable and required for every function, water is biology’s ultimate multitasker. It even changes state when perspiration evaporates off the skin surface; and, in the act of being discharged through the skin, urine, or bowels, creates the ongoing demand for its own replenishment. LESS