Osmosis and Sodium (salt)

Two friends of mine were rushed to the hospital after suffering mental confusion and a general feeling of being “shut down.” One of them said she was certain she was on the verge of death. The other said she was so weak, she couldn’t function. Both women were diagnosed with sodium deficiency.

What is sodium deficiency?

There is not enough sodium in your bloodstream. Sodium comes mainly from salt (sodium chloride) but can come from other sources, too. (Baking soda contains sodium in the form of sodium hydrogen carbonate.) Every cell in your body contains sodium. There must be a correct balance between the sodium in your bloodstream and in your cells. Your body naturally corrects the balance in most situations. But if the sodium levels in your bloodstream are very low, compared to that in your cells, your cells will swell.

A common cause of sodium deficiency in humans

…is from drinking too much water. It would be very unlikely that eating less salt would cause a sodium deficiency. Instead, drinking too much water lowers the percentage of salt in your blood. Athletes such as runners need to drink lots of water to replace that lost by sweating. But they don’t drink plain water; they drink liquids such as Gatorade that contain sodium and other minerals. Thus, they are getting water without diluting the salts in their bloodstream.

Death from drinking too much water! The following news article, from the Associated Press, details how a woman died from “water intoxication” after taking part in a contest to see who could drink the most water without urinating. Note that one of her symptoms was a massive headache (brain cells swelling)

Jan. 13, 2007, 7:10 PM PST / Source: The Associated Press

A woman who competed in a radio station’s contest to see how much water she could drink without going to the bathroom died of water intoxication, the coroner’s office said Saturday.

Jennifer Strange, 28, was found dead Friday in her suburban Rancho Cordova home hours after taking part in the “Hold Your Wee for a Wii” contest in which KDND 107.9 promised a Nintendo Wii video game system for the winner.

“She said to one of our supervisors that she was on her way home and her head was hurting her real bad,” said Laura Rios, one of Strange’s co-workers at Radiological Associates of Sacramento. “She was crying and that was the last that anyone had heard from her.”

It was not immediately know how much water Strange consumed.

A preliminary investigation found evidence “consistent with a water intoxication death,” said assistant Coroner Ed Smith.

Water follows sodium, is a basic rule. If there is too little sodium in your blood, there will be more inside your cells. Water will flow into the cells (water following sodium) and they will swell. If this happens in the brain, cognitive problems may occur. If heart cells swell, your heart might stop.

Water can pass through your cell membranes through osmosis. That is, liquids passing through a semipermeable membrane to equalize concentrations.

Activity 1: Observe how cells swell with a sodium imbalance

  1. Put a raw egg in a glass of vinegar to cover, and allow to stand overnight or until the shell has dissolved. Gently rub off any remaining shell. The cell membrane will remain, which is porous and allows osmosis to occur. Observe the size of the egg either visually, or by weighing it. You might want to photograph the egg next to another object for comparison
  2. Put the membranous egg into a glass of tap or distilled water, to cover. Allow to sit overnight or longer. Then compare the size of the egg to the original egg. It will have swollen to a larger size.
  3. Why is the egg larger? There was more sodium inside the egg membrane than in the surrounding water. Water follows salt, so water moved into the egg.

Activity 2: Observe water following sodiumreversal of above experiment

Peel and slice a potato. Try to keep the slices equal in width. Fill two glasses with water. In one glass, add 2 – 3 tablespoons of salt and stir to dissolve. Put one slice in regular water, and the other in salt water. The potato slices contain water and represent your cells. The fresh and salt water represents your bloodstream.

Observe after several hours, and again after 24 hours. What has happened to the slices? Can you explain?

Expected results and explanation:

The slice in the salty water should be flexible and may appear shriveled. The slice in the regular water should be firm. The water in the potato followed the salt…and flowed out of the potato into the salt water. Those potato slices then became floppy. The slices in the plain water remain stiff. They don’t lose water to the container, and may even have absorbed a little.

Why is it so dangerous for your cells to swell?

In your brain, that can cause mental disfunction. One of my friends suffered memory loss and anger outbursts. Doctors related both of these to her sodium deficiency.

In your heart, the electric pulses that cause your heart to beat can be disrupted. Swollen heart cells are not able to carry electricity efficiently.

Cells throughout your body are affected, causing liver and kidney problems as well as a host of other life-threatening issues, if your sodium isn’t brought into balance.

How does sodium deficiency occur?

In most situations, your body will take care of balancing your salt, in a process called homeostasis. Doctors believe one of my friends was drinking far too much water throughout the day (10 – 12 glasses); doctors were unable to find the cause in my other friend but were able to correct her condition with electrolyte fluids and observation.

Science yields clues to an ancient salt mine

Two Experiments Help Solve a Mystery

“Residents mined and traded salt” The sign offered little information, but I wanted to know more. Ruins of an ancient Anasazi settlement were huddled into a cliff above a sinkhole full of green water and leeches. “Where did they mine salt?” I asked a ranger. He directed me to nearby Camp Verde. “Look for Salt Mine Road and just keep driving. You’ll see white mounds.” So I was off.

Cliff Dwellings Montezuma Well, New Mexico

These mounds had been worked in historic times. Lumber and twisted railroad ties lay on the ground. I strode up the mound and scooped up the white powdery material, then tasted it. It wasn’t table salt as I knew it, but did have a taste of salt mixed with … something else. Dirt was liberally mixed with the salt.  Was this material good for health? Was it sodium chloride (table salt) or something else? How was the dirt removed before eating? Or was it removed? 

Mine Workings

Crystal structure of sodium chloride could provide some clues. Common salt crystals are cubic. (Not in your salt shaker, as the crystals have been ground to a powder). As I continued to wander, I discovered a salt seep and water running from it. Where the water dropped over a rocky ledge, salty icicles hung. These were pure mineral so I broke off a few icicles and placed them in an empty coffee cup I was carrying. I would analyze these later. I peered closely at some crystal fragments drying in the sun. They weren’t cubic; the white crystals were slender needles. By the way, exploring can be messy. My feet sank unexpectedly into deep goo near the salt creek, leaving my shoe behind. I dug around for it; then walked back to my car with mud peeling off my legs. I washed off in what happened to be a historic irrigation ditch down the road.

I washed off in the Camp Verde Ditch

Experiment: grow crystals

Here’s how to analyze those crystals and discover what they might be. You can do this experiment with many common substances: salt, epsom salts, sugar. Dissolve clean grains in pure water. Start with 1/2 cup of water and dissolve as much powder as the water will take. If you heat the water first, you will be able to dissolve more powder because hot water dissolves salts more easily. Stir until theThen pour the solution onto a cookie sheet with rims to keep it from running off. If you line the cookie sheet with black construction paper, the crystals will be more visible but that’s optional. Put the cookie sheet near a window where it will get indirect sunlight and wait for the water to evaporate. Crystals will be left behind. I learned the hard way not to put the cookie sheet under direct hot sunlight. Evaporation will proceed so rapidly that good crystals don’t have time to grow. But this could be another experiment! Put one tray in the heat of summer sun and another in bright but indirect light near a window. Compare the two.

Observe the shape of the crystals. If they’re cubic, you have sodium chloride. If it’s needles, you may have magnesium sulfate. (epsom salts).

Magnesium Sulfate Crystals

Experiment: Clean dirty salt

If you don’t have clean crystals, you’ll have to remove the dirt first. How to do this? Dissolve the material, dirt and all, in water and pour it through a filter. I use paper towels or cloth in a colander. Then you can proceed as above. You can also try growing crystals using dirty salt/powder. How are they different from the cleaned substance?

How did the ancient Anasazi clean the salt? They had no paper towels, colanders, and possibly no cloth as we know it. Think about this. Perhaps they let the “salt” water solution sit in a pot until the dirt settled out, then poured off the liquid for evaporation. Did they have flat stones for an evaporative surface? Or did they mix the salty solution into their foods? Or eat the salt with the dirt included?

What were the effects of eating magnesium sulfate? This mineral is actually important for many cellular functions and is sometimes used as a laxative. There are rarely negative side effects from eating it, but using it in place of salt may have left a salt deficiency in Anasazi diets. Sodium chloride is vitally important for survival. If they weren’t getting it from the “salt” mine, what other sources of salt were available? Meat and blood are one source. Some desert plants contain salt.

NOTE: The term Anasazi is outdated, but I use it here because it is still widely understood. Today’s Hopi Indians are descendants of the “Anasazi” so ancestral Hopi is a better description of cliff dwellers at Montezuma’s Well.