Nutrition Chapter 7: Nutrients Involved in Fluid and Electrolyte Balance

We lose fluids through

All of the above

Thirst Mechanism

A cluster of nerve cells in the hypothalamus that simulate our conscious desire to drink fluids in response to an increase in the concentration of salt in our blood or a decrease in blood pressure and blood volume.

Hyperkalemia

A condition in which blood potassium levels are dangerously high

Hypokalemia

A condition in which blood potassium levels are dangerously low

Hypernatremia

A condition in which blood sodium levels are dangerously high

Hyponatremia

A condition in which blood sodium levels are dangerously low

Which of the following people probably has the greatest percentage of his or her weight as body fluid?

A healthy infant of average weight

Fluid

A substance composed of molecules that move past one another freely. Fluids are characterized by their ability to conform to the shape of whatever container holds them.

Electrolyte

A substance that disassociates in solution into positively and negatively charged ions and is thus capable if carrying an electric current

Diuretic

A substance that increases fluid loss via the urine. Common diuretics include alcohol, some prescription medications, and many over-the-counter weight-loss pills.

Solvent

A substance that is capable of mixing with and breaking apart a variety of compounds. Water is an excellent solvent.

Water Content of Different Foods

Almonds- 5% Porch chop, lean, broiled- 61% Sweet potato, baked- 76% Olives, ripe, canned- 80% Pineapple, raw- 86% Peaches, raw- 89% Cucumbers, with peel, raw- 95% Lettuce, iceberg- 96%

Ion

An electrically charged particle, either positively or negatively charged

Functions of Chloride

Couple with sodium in the extracellular fluid, chloride assists with the maintenance of fluid balance. Chloride is also a part of HCl in the stomach, which aids in preparing food for further digestion. Chloride works with the white blood cels of our body during an immune response to help kill bacteria, and it assists in the transmission of nerve impulses.

Plasma is one example of

Extracellular fluid

Our thirst mechanism signals that we need to replenish fluids, but it is not sufficient to ensure that we are completely hydrated.

False

Recent research suggests that caffeine intake has virtually no effect on fluid balance.

False

Sodium is a nutrient necessary for health, but we should not consume more than recommended amount.

False

Hypernatremia commonly occurs when we are dehydrated.

False. Hypernatremia is commonly caused by a rapid intake of high amounts of sodium

Drinking lots of water throughout a marathon will prevent fluid imbalances.

False. In addition to water, the body needs electrolytes, such as sodium and potassium, to prevent fluid imbalances during long-distance events such as a marathon. As purified water contains no electrolytes, this would not be the ideal beverage to prevent fluid imbalances during a marathon.

A decreased concentration of electrolytes in our blood stimulates the thirst mechanism.

False. Our thirst mechanism is triggered by an increase in the concentration of electrolytes in our blood.

Absence of thirst is a reliable indicator of adequate hydration.

False. Quenching our thirst does not guarentee adequate hydration. Urine that is clear or light yellow in color is one indicator of adequate hydration.

Conditions that increase fluid loss include constipation, blood transfusions, and high humidity.

False. These conditions are associated with decreased fluid loss or an increase in body fluid. Diarrhea, blood loss, and low humidity are conditions that increase fluid loss.

Which of the following is a characteristic of potassium?

It can be found in fresh fruits and vegetables

Which of the following is true of the cell membrane?

It is freely permable to water but impermeable to solutes

DRI for Adults (19-50)

Men- 3.7 L of total water per day Women- 2.7 L of total water per day

High-Sodium Foods and Lower-Sodium Alternatives

P 240

Functions of Phosphorus

Phosphorus works with potassium inside cells to maintain proper fluid balance. It also plays a critical role in bone formation, as it is a part of the mineral complex of bone. In fact, about 85% of our body's phosphorus is stored in our bones. As a primary component of adenosine triphosphate (ATP), phosphorus plays a key role in creating energy for our body. It also helps to regulate many biochemical reactions by activating and deactivating enzymes. Phosphorus is a part of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), and it is a component in cell membranes (as phospholipids) and lipoproteins.

Functions of Potassium

Potassium and sodium work together to maintain proper fluid balance and regulate the transmission of nerve impulses and the contraction of muscles. And in contrast to a high-sodium diet, a diet high in potassium actually helps maintain a lower blood pressure.

4 Major Minerals in Water (Salts)

Sodium (+) Potassium (+) Chloride (-) Phosphorus(-)

Functions of Sodium

Sodium has a variety of functions. As discussed earlier in this chapter, it is the major positively charged electrolyte in the extracellular fluid. Its exchange with potassium across cell membranes allows cells to maintain proper fluid balance, blood pressure and acid-base balance. Sodium also assists with the transmission of nerve signals and aids in muscle contraction. To review, the release of sodium from inside to outside the cell stimulates the spread of nerve signals within nervous tissue. The stimulation of muscles by nerve impulses provides the impetus for muscle contraction.

Recommended Intake of Nutrients Involved in Hydration and Neuromuscular Function

Sodium- 1.5 g/day Potassium- 4.7 g/day Chloride- 2.3 g/day Phosphorus- 700 mg/day

Blood Volume

The amount of fluid in blood.

Intracellular Fluid

The fluid held at any given time within the walls of the body's cells. 2/3 of adult's body fluid.

Extracellular Fluid

The fluid outside the body's cells, either in the body's tissues or as the liquid portion of blood, called plasma. 1/3 adult's body fluid.

Phytic Acid

The form of phosphorus stored in plants

Insensible Water Loss

The loss of water not noticeable by a person, such as through evaporation from the skin and exhalation from the lungs during breathing.

Osmosis

The movement of water (or any solvent) through a semipermeable membrane from an area where solutes are less concentrated to areas where solutes are highly concentrated.

Metabolic Water

The water formed as a by-product of our body's metabolic reactions.

Sensible Water Loss

Water loss that is noticed by a person, such as through urine output and visible sweating.