what is the physiology behind water intoxication?

Answer 1

The human body is a giant electro-chemical reaction and has to be in balance to work correctly.

When you drink too much water (as that poor lady in California did and died) the water throws off the balance of salts, electrolytes, chemicals in your body. You basically end up drownding in your own fluids.

This is one reason gatorade/pedalite works well to rehydrate the body. It's not just water, but salts and sugars that help your electro-chemical reaction maintain balance.

Answer 2

I was under the impression that the body was intoxicated as in the meaning of over full, not "drunk". So much so that the body can't expel as much as it can consumes in that time frame. I still can't fathom how the woman died from intoxication. You would think the body would force you to expel the excess in a conscious state. That it would take more than just will power to be able to consume that much.

Answer 3

ever notice how your fingers wrinkle up if you bathe or swim too long? Imagine doing that to every cell in your body. They explode from the excess water pressure. Chemical requirements cause the cells to suck up water in an effort to reach equilibrium with the fluid system, and like a balloon, cells only expand so much before breaking, and even when they do not burst, the dilution of everything inside the cell causes them to slow down and die. You essentially drown yourself from the inside.

Answer 4

Water goes into blood stream and has a low salt concentration as comapered to tissues (brain), the fluid is considered hypotonic (low salt). The body will try to equilibriate (make the salt and fluid concentrations the same) in the blood and brain fluids. So....the hypotonic fluid in the blood will diffuse in to the relatively hypertonic brain tissue causing the brain tissue to swell. If you havent noticed the skull does not have a lot of extra room for swelling so it develops very high pressure on the brain leading to death.

Answer 5

[edit] Physiology of water intoxication
Body fluids contain electrolytes (particularly sodium compounds, such as sodium chloride) in concentrations that must be held within very narrow limits. Water enters the body orally or intravenously and leaves the body primarily in the urine, sweat and by exhaled water vapour. If water enters the body more quickly than it can be removed, body fluids are diluted and a potentially dangerous shift in electrolyte balance occurs.

Most water intoxication is caused by hyponatremia, an overdilution of sodium in the blood plasma, which in turn causes an osmotic shift of water from extracellular fluid (outside of cells) to intracellular fluid (within cells). The cells swell as a result of changes in osmotic pressure and may cease to function. When this occurs in the cells of the central nervous system and brain, water intoxication is the result. Additionally, many other cells in the body may undergo cytolysis, wherein cell membranes that are unable to stand abnormal osmotic pressures rupture, killing the cells. Initial symptoms typically include light-headedness, sometimes accompanied by nausea, vomiting, headache and/or malaise. Plasma sodium levels below 100 mmol/L (2.3g/L) frequently result in cerebral edema, seizures, coma, and death within a few hours of drinking the excess water. As with alcohol poisoning, the progression from mild to severe symptoms may occur rapidly as the water continues to enter the body from the intestines or intravenously.

A person with two healthy kidneys can excrete about 900ml (0.24 gal)/hr[2]. Consuming as little as 1.8 litres of water (0.48 gal) in a single sitting may prove fatal for a person adhering to a low-sodium diet, or 3 litres (0.79 gallons) for a person on a normal diet. However, this must be modulated by potential water losses via other routes. For example, a person who is perspiring heavily may lose 1 L/hr (0.26 gal) of water through perspiration alone, thereby raising the threshold for water intoxication. The problem is further complicated by the amount of electrolytes lost in urine or sweat, which is variable within a range controlled by the body's regulatory mechanisms. Water intoxication can be prevented by consuming water that is isotonic with water losses, but the exact concentration of electrolytes required is difficult to determine and fluctuates over time, and the greater the time period involved, the smaller the disparity that may suffice to produce electrolyte imbalance and water intoxication.

Sodium is not the only mineral that can become overdiluted from excessive water intake. Magnesium is also excreted in urine. According to the National Institutes of Health, "magnesium deficiency can cause metabolic changes that may contribute to heart attacks and strokes."[3] Intravenous magnesium is used in cardiac care units for cardiac arrhythmias.[4]