Salt is made of sodium and chloride—salt is essential for life. The chemical symbol for sodium, Na, is derived from the Latin name for sodium, natrium. Most people enjoy the taste-enhancing flavor of salt. Less than 10 percent of salt intake is from the salt in unprocessed foods such as fruits and vegetables. Three-quarters of the salt most people eat is hidden in processed foods. Many processed foods have a high sodium content without tasting salty. About 10 percent of normal salt intake is from salt added in the kitchen or at the table.
Three-quarters of the salt most people eat is hidden in processed foods.
Most natural foods start out with an abundance of potassium and very little sodium. During food processing, this balance gets reversed. Processed foods contain less potassium and excess sodium. An apple starts with only one milligram of sodium. The same weight of apple pie has 266 mg of sodium, as seen in Figure 8-3. One teaspoon of salt weighs about five grams, and contains 2000 mg sodium (40 percent sodium). The maximum safe amount of sodium per day is set at 2400 mg sodium, just over a teaspoon of salt. Few people stay below the safe level.
Sodium (a cation, Na+) and chloride (an anion, Cl−) are the most abundant ions in the fluids outside of cells (extracellular fluid). Sodium is important for maintaining blood pressure and fluid balance. Sodium retention in the kidneys can result in increased water retention, which can result in increased blood pressure. The kidneys remove all sodium from the blood and then add back just the right amount of sodium to the blood. To adjust acid-alkaline balance and lower blood acidity, the kidneys can excrete hydrogen ions (H+) and exchange them for sodium ions (Na+).
Sodium is absorbed directly from the intestinal tract. Sodium travels freely in blood and interstitial fluid. Excess sodium causes thirst, which triggers extra water intake. This extra water flushes the extra sodium out through the kidneys.
Figure 8-3 Sodium is increased in food processing.
CELL MEMBRANE POTENTIAL
The sodium-potassium pumps in cell membranes maintain concentrations of sodium and potassium, which are very different inside the cell than they are outside the cell. Sodium concentrations are 10 times higher outside cells than inside cells. Potassium concentrations are thirty times higher inside cells than outside cells, as shown in Figure 8-4. The active pumping of sodium and potassium requires energy.
It has been estimated that about 30 percent of the energy used in the body at rest is used to maintain this pumping action. The different concentrations of these minerals create an electrochemical gradient known as the membrane potential. The control of cell membrane potential is critical for heart function, nerve impulse transmission, and muscle contraction.
More about Sodium:
Three-quarters of the salt most people eat is hidden in processed foods.
Most natural foods start out with an abundance of potassium and very little sodium. During food processing, this balance gets reversed. Processed foods contain less potassium and excess sodium. An apple starts with only one milligram of sodium. The same weight of apple pie has 266 mg of sodium, as seen in Figure 8-3. One teaspoon of salt weighs about five grams, and contains 2000 mg sodium (40 percent sodium). The maximum safe amount of sodium per day is set at 2400 mg sodium, just over a teaspoon of salt. Few people stay below the safe level.
Sodium (a cation, Na+) and chloride (an anion, Cl−) are the most abundant ions in the fluids outside of cells (extracellular fluid). Sodium is important for maintaining blood pressure and fluid balance. Sodium retention in the kidneys can result in increased water retention, which can result in increased blood pressure. The kidneys remove all sodium from the blood and then add back just the right amount of sodium to the blood. To adjust acid-alkaline balance and lower blood acidity, the kidneys can excrete hydrogen ions (H+) and exchange them for sodium ions (Na+).
Sodium is absorbed directly from the intestinal tract. Sodium travels freely in blood and interstitial fluid. Excess sodium causes thirst, which triggers extra water intake. This extra water flushes the extra sodium out through the kidneys.
Figure 8-3 Sodium is increased in food processing.
CELL MEMBRANE POTENTIAL
The sodium-potassium pumps in cell membranes maintain concentrations of sodium and potassium, which are very different inside the cell than they are outside the cell. Sodium concentrations are 10 times higher outside cells than inside cells. Potassium concentrations are thirty times higher inside cells than outside cells, as shown in Figure 8-4. The active pumping of sodium and potassium requires energy.
It has been estimated that about 30 percent of the energy used in the body at rest is used to maintain this pumping action. The different concentrations of these minerals create an electrochemical gradient known as the membrane potential. The control of cell membrane potential is critical for heart function, nerve impulse transmission, and muscle contraction.
More about Sodium:
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