How come urine is yellow but we drink colored liquids?

Urine Color as Health Indicator
by Ron Kurtus (20 May 2005)

The kidneys process liquids from what you have been eating and drinking, as well as material from various body processes. The resulting urine consists of water and dissolved waste material. Since some organ malfunctions or the effort to fight off a disease can results in excess waste material, the color of the urine can be an indicator of what you have been ingesting and the condition of your health. Certain colors can indicate problems, diseases or imbalances in your diet.

Urine
Urine consists of water and dissolved waste material from what you have been drinking and eating. It also includes dead blood cells and other material the body wants to eliminate.

The kidneys process the blood plasma, allowing water, sugars, vitamins, amino acids and other vital substances back into the bloodstream. They eliminate excess water, salts and minerals, as well as urea from protein digestion, uric acid, creatinine from muscle breakdown, hormone waste and toxins. Also eliminated is urochrome, which is a yellow pigment that comes from the processing of dead blood cells in the liver.

The urochrome gives the urine a pale yellow color, which is its normal color.

Abnormal colors
Since the normal color of urine is pale yellow, variations can be an indication of health problems or be the result of certain foods that have been eaten.

Clear urine
If a person has been drinking an excess of water or diuretics such as coffee or beer, the urine may have little or no color. Typically, it is nothing to worry about if it happens occasionally.

Yellow urine
Excess sweating could result in the urine becoming a deeper yellow. Also, it is a sign that you have not been drinking enough liquids

Dark yellow urine
Liver problems or jaundice can cause the urine to become consistently a dark yellow color. Be sure you have been drinking enough fluids before jumping to conclusions.

Orange urine
People who eat too many carrots--like from a juicer--may see orange urine. Also, too much Vitamin C can turn the urine orange.

Brown urine
Brown urine can an indication of a serious condition. It could be caused by liver disease, hepatitis, melanoma cancer, or copper poisoning. Other symptoms from those ailments should also be considered as indicators. But note that if you had recently eaten fava beans or taken a laxative, your urine also could turn brown.

Greenish urine
A urinary tract infection, bile problems and certain drugs can cause the urine to turn greenish. A brighter green color is an indication of an excess of B vitamins.

Blue urine
Urine with a bluish tint can be caused by a psuedomonas bacterial infection. It can also be an indication of high levels of calcium.

Reddish urine
There are a number of things that can cause the urine to have a red tint.

Blood
A small amount of blood in the urine can give it a red tint. Sometimes droplets of blood are seen. A bladder infection, kidney stones or bladder stones can result in urine with red in it. Also, a slight injury to the bladder or kidney can result in bleeding into the urine. Some professional boxers have been known to pass blood in their urine after a fight.

If you see what looks like blood in your urine, it is a good idea to go to the doctor to check the condition.

Food
Eating beets can result in reddish-purple urine.

Acidic urine will turn red after eating blackberries. Alkaline urine will look reddish after eating rhubarb. Whether your urine is acidic or alkaline is usually determined by other foods you have eaten.

Candy or pills with a dye can temporarily turn the urine red.

Poison
Lead or mercury poisoning can turn the urine reddish. If you suspect you have ingested and have been handling those toxic metals, and your urine is red, you should see your physician.

What to do
If your urine has a strange color, and you have not been eating foods or taking pills that would cause the change in color, you should check yourself for other unusual symptoms and perhaps visit your doctor.

Also, if the urine has a bad odor, it may be an indication of disease.

Summary
The color of your urine may determine the state of your health. Your kidneys process liquids from what you have been eating and drinking, and the resulting urine consists of water and dissolved waste material. Certain colors of your urine can indicate problems, diseases or imbalances in your diet.

Why is the Grass Green?

(Lansing State Journal, April 8, 1992)

For that matter, why is anything any color at all? In the last Science Theatre column on why snow is white, we said that the light we see things with from the sun, from our light bulbs is called white light and can be broken down into the colors in the rainbow in order of their wavelengths.

The snow is white because all the colors are reflected and refracted equally without any color range dominating.

This is not so when white light hits objects which we don’t see as white or gray.

Most objects tend to reflect only some of the light falling on them. The light contains all of the colors, but the objects reflects selected colors and absorbs the rest.

This is called "subtractive color mixing" because some of the colors are subtracted out of the light.

Grass appears green because all of the colors in the rainbow are absorbed into the leaves of the grass except green.

What causes people to have to wear glasses?

From "Neuroscience for Kids"

Do You Wear Glasses? Here's Why!

Have you ever seen this "eye chart" before? It is smaller than the real version of the chart that is used to test how well you can see. It was first developed in 1863. If you have 20/20 vision, it means that at a distance of 20 feet, you can read a certain line (labeled 20) on the chart and that your vision is normal. If you can only see the top line clearly (the one labeled 200), then you have 20/200 vision. This means that you must be 20 feet from the chart to see what most people can see at 200 feet. By the way, if someone's vision is 20/200 or worse, then they are legally blind.

People wear glasses for several reasons. People who have "fuzzy" vision when they look at distant objects are called nearsighted (myopia). In these people, the image is focused in front of the retina. The lens of glasses needed to correct vision in nearsighted people is concave. People who need glasses for reading and who have "fuzzy" vision for objects close to them are called farsighted (hyperopia). In farsighted people, objects are focused behind the retina. The lens of glasses needed to correct vision in farsighted people is convex. Astigmatism is another reason that you might have to wear glasses.

So what causes myopia? There are many different causes. When the eye is too long it results in Axial Myopia. When an eye is too strong because the cornea or the lens is too strong then you have Refractive Myopia . Either way, the treatment is glasses, contacts or Refractive Surgery.

So what causes hyperopia? Like myopia, there are many different causes. When they eye is too short it results in Axial Hyperopia. When the eye is too weak to focus the image on the retina it results in Refractive Hyperopia.

Astigmatism can be caused by the cornea, the lens or both. Small amounts of astigmatism occur naturally, but larger amounts start to cause blurriness, smeared images or shadowed images.

Did you know?

Approximately 160 million people in the US wear glasses or contact lenses. (That's more than half of the people that live in the US.)

How do you produce saliva?

Saliva is produced in the salivary glands. It is an important compound since it mixes in with your favorite foods right before it goes down the esophagus and into the stomach. There are three salivary glands: the parotid gland (located at the back of the mouth right next to the ears), the submandibular (or submaxillary) gland (located underneath the tongue at the back of the mouth), and the sublingual gland (located behind the chin). Saliva is made up of mostly water. It also contains mucus and many electrolytes such as: sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate. Mucus in saliva mainly consists of mucopolysaccharides (complex sugars) and glycoproteins.Most of the saliva is made while a person is awake. When asleep, the body produces almost no saliva.

There are many antibacterial compounds such as thiocyanate and hydrogen peroxide. Many enzymes are also found in saliva such as amylase which starts the digestion of starch; lipase digests fat before the food is even swallowed. Amylase and lipase work best at a pH of 7.4. Lysozyme causes lysis in bacteria. Lingual lipase mixes with the food but is not activated until it enters the acidic environment of the stomach.

Saliva also mixes with many cells. Possibly as much as 8 million human and 500 million bacterial cells per milliliter mix in with the saliva.

Opiorphin, a pain-killing substance, is also found in human saliva. Opiorphin has the potential, depending on the quantity, to be about five times stronger than morphine.

In insects salivary glands are used to produce silk and glues.

The complex stew that is saliva may explain why sometimes people lick their wounds and why animals clean themselves with their tongues (instead of toilet paper).