Nutrition: Hydration Chapter 4

Water At Work


Water & The Urinary System

Waste Removal: Purifying with Pressure

Urine forms in the kidneys, with water being the most important substance in the delivery, filtration, and excretion of liquid waste. Much like a gulp of water sluices chewed food down the esophagus and into the digestive tract, the water in blood helps to carry all variety of molecules through the bloodstream. Those substances that are unwanted (e.g., toxins), unneeded (leftover electrolytes), or in excess (extra protein and vitamins) are filtered out as the watery blood passes through the kidneys, straining out impurities and excess water. READ MORE

From the kidney, water helps carry the impurities out through the ureter and into the bladder. As liquid waste fills and distends the elastic sac of the bladder, the pressure resulting from increased water volume trips a signal to the brain: it’s time to release waste. With the relaxing of the urinary sphincter (a ring of muscle at the base of the bladder), pressure on the bladder is relieved as urine is expelled through the urethra.

While water consumption is easily relatable to urine output, staying hydrated has a healthful effect on excreting solid waste as well, since water helps break down food and wash it through the gastrointestinal tract. Dehydration, by contrast, slows GI function and hardens the stool. Drinking plenty of water is the first preventive measure to avoid constipation. LESS


Prevention And Protection

Our bodies utilize water to preventive and therapeutic effect similarly to how we use water in daily activities. Just as we wash dirt from our skin (or our cars, for that matter), surfaces inside the body are cleansed and lubricated as their cells are bathed in water. Tears, for instance, clear dirt from the eyes. In food preparation we use water to hydrate pasta, which is not entirely unlike the way our skin gains volume and elasticity. Water softens pasta and other dried foods much like saliva helps soften food for breakdown and safe ingestion. READ MORE

Additionally, mucous membranes of the respiratory system are more effective at trapping the pathogens that cause disease when moistened by hydration. In another protective measure, the pressurized water within joints, tendons, muscle, and fat helps areas of the body function like gel-filled football pads, providing cushion against shock. LESS


Regulating Temperature

Due to its ability to cool and warm the body, the water in your bloodstream is sometimes likened to the antifreeze that circulates in a car engine. The simile is appropriate, too, except that your body is far smarter than an automobile. Not only does it have the ability to cool the body on a need basis; it can even adjust to different temperatures at specific sites. That’s right: not all of your body is running at 98.6 degrees Fahrenheit. READ MORE

When you see someone’s skin become red from heat or exertion, it is due to a rush of blood. What’s happening is that blood shunts closer to the surface of the skin so that it can be cooled. With the help of perspiration, the skin surface cools down and exchanges heat from the blood. The cooled blood then circulates toward the core, keeping the entire body at a reasonable temperature. Going back to our engine comparison, antifreeze regularly passes through the fins of a radiator, which provide greater surface area through which heat can escape; our body is cooled in a similar manner, with our entire outer layer of skin providing surface area for heat release. LESS


Moving Nutrients

Nutrient Breakdown

Water is a key ingredient in nutrient metabolism, which is the process of converting food into energy. Unlike any other physical or chemical component of metabolism, water is involved throughout the metabolic process, and it all begins with the breakdown of foods in the mouth. There, water is an ingredient within saliva, which soaks and softens foods so that they can more easily be chewed and swallowed. Sugars, salts, and nutrients such as B-complex vitamins and Vitamin C are water-soluble, meaning that they dissolve in water. All nutrients have to dissolve, but some are broken down in lipids (fats) rather than in water. READ MORE

Nutrient Transport

Water transportation is a familiar concept, but of course there is no surface on which to travel in our closed circulatory system. Rather than riding buoyantly like boats on the sea, molecules of nutrients move in the bloodstream more like small fish at the mercy of the tide.

Once food is broken down into molecules in the upper digestive tract, the nutrients pass through the permeable walls of the small intestine and into the bloodstream together with ingested water. In the fast-moving bloodstream, which gains fluency thanks to its watery constitution, nutrients are carried to the body’s cells or to the kidneys as waste. LESS

The material on this site is for informational purposes only and is not intended as medical advice. It should not be used to diagnose or treat any medical condition. Consult a licensed medical professional for the diagnosis and treatment of all medical conditions and before starting a new diet or exercise program. If you have a medical emergency, call 911 immediately.