- Sodium ions are the principal cations found outside cells in the body. They help regulate and control the level of body fluids. Too little leads to diarrhea, anxiety, a decrease in body fluids, and circulatory failure. However, most people have the opposite problem—too much sodium ion—ingested mainly as table salt and salty snack foods. Too much increases water retention, leading to high blood pressure (hypertension). About 50 million people in the United States suffer from hypertension. Uncontrolled hypertension can lead to stroke, heart attack, kidney failure, or heart failure. Antihypertensives are among the most prescribed drugs in the United States.
- Potassium ions are the principal cations found inside cells in the body. Bananas, orange juice, and potatoes are good sources of Potassium ions help regulate cellular functions, including nerve impulses and heartbeats, and the level of body fluids.
- Chloride ions are the principal anions found outside cells in the body. They serve as counterions (ions necessary to balance electrical charge) for in the extracellular fluid and for in gastric juice. Like chloride ions are ingested mainly as table salt. Like sodium and potassium ions, chloride ions are involved in maintaining acid–base and fluid balances. It is difficult to separate the effect of too much from that of too much both seem to be involved in hypertension. Too little dietary is rare, but it can result from heavy sweating, chronic diarrhea, and vomiting.
- Calcium ions occur mainly in the skeleton and account for 1.5–2% of body mass. is therefore essential for building and maintaining bones and teeth. Also, plays a crucial role in blood clotting, muscle contraction, and the transmission of nerve signals to cells. An adequate supply of is especially important during pregnancy and in growing children. It helps to prevent osteoporosis in older people. Good sources of calcium are milk and other dairy products, nuts, and legumes.
- Magnesium ions like are found mainly in the bones, but they are also vital components of many enzymes, which are substances our bodies need in order to release energy from the food we eat. Good sources of are green vegetables ( is a component of the chlorophyll in all green plants), milk, bread, cereals, and potatoes.
- Phosphate ions exist mainly as and in body fluids. About 85% of the phosphorus-containing ions in the body are in the bones, where they act as the counterions for Also, they play an important role in energy production from food. Good sources of phosphate are milk and other dairy products, cereals, and meat.
- In addition to the above ions, the body needs smaller amounts of ions found in trace minerals. These include the ions iron(II), chromium(III), copper(II), zinc, fluoride, iodide, and bicarbonate, as well as the hydrogen ion. Also required are compounds of manganese, molybdenum, and selenium, although these are not necessarily in the form of simple ions. These trace minerals play a variety of roles, several of which are discussed in other chapters.
Electrolytes, or in other words compounds that are ionizable in solution, play an essential role in many body functions. Cells create electrical energy as ions move from the solutions inside the cells of our body to the solutions outside the cells. This form of energy is a staple in the normal function of man body systems. For example, the nervous system uses electrical energy, termed nerve impulses, to transmit messages from one cell in the body to another cell in the body. This manifests as muscle movement, glandular secretion, excretion, temperature regulation, and even mental thought. Let us analyze, in more detail, the role of certain ions in some body functions.
In the body, fluids both inside and outside the cells are electrolyte solutions. This means they are water suspensions of ions. The electrolyte solutions both inside and outside the cells contain equal amounts of positive (cations) and negative (anions) ions making the body as a whole electrically neutral (see Table 1). The limiting boundary of the cell, the cell membrane, separates these ionic solutions.
Generally, a very small excess of anions accumulates immediately inside the cell membrane along its inner surface, and an equal number of cations accumulates immediately outside the cell membrane. This is the resting state of the cell. This difference in ion concentration on the adjacent surfaces of the cell membrane creates an electrical energy potential or electrochemical gradient. This is very similar to a battery where one end has a larger concentration of positively charged particles and the other end a greater concentration of negatively charged particles. Completing the circuit by connecting the ends of the battery, allows charged particles to move between the two ends creating energy as an electrical current. A similar energy source arises in the body as charged ions move across the cell membrane.
In our bodies, the nervous and muscular systems use the electrolyte properties of ionic sodium and potassium, assisted by lesser trace elements ( e.g. copper) to generate currents across the membranes of their cells. This current, or movement of charged particles, results from the electrochemical gradient set up across the cell membrane. The electrochemical gradient sets up the two types of movement that produce the current. The chemical gradient results in the passive movement of ions from a region of higher concentration to a region of lower concentration. The electrical gradient creates a movement of ions of one charge to an area of ions of the opposite charge. The result of this current is the transmission of nerve impulses and the contraction of muscle tissue.
The ionic particles of the nervous impulse can be visualized in the following simplified process. Neurons, the conducting cells of the nervous system, communicate by generating and propagating action potentials. An action potential is an abrupt pulse-like change in the positive-negative charge differential on either side of the nerve cell membrane. This results in a change of the resting potential of the cell. This can be caused by any factor that suddenly increases the permeability of the cell membrane for positively charged sodium ions. This movement of ions results in a flow of charged particles into and out of the cell, creating an electrical current. The replication of this process to adjacent areas of the cell membrane forms the electrical message, or nervous impulse, that moves along the nerve cell toward another cell in the body. This propagated action potential then becomes the energy source that initiates body functions ranging from muscle contraction to creative thought.
Ions, as we can see, play an important role in the body. Calcium, potassium, sodium, chloride, and copper ions are some key ions that participate in the body's electrical events. Potassium is the major positive ion inside the cell. Sodium is the major positive ion found in the fluid outside the cell. Ionic chlorine is the most abundant negative ion. Imbalances of any of these ions or certain trace ions in the body or inhibition of sodium ion transport across the cell membranes can lead to dysfunction in the conduction of electrical messages. This dysfunction quickly leads to a general body disturbance and loss of ability to maintain somewhat stable internal conditions. We then come back to the problem we faced when we started this article saying, "We just do not have enough energy."
|Oxygen||A major contributor to both organic and inorganic molecules; as a gas it is necessary for the production of cellular energy.|
|Carbon||The main component of all organic molecules, i.e. carbohydrates, lipids, proteins, and nucleic acids.|
|Hydrogen||Another component of all organic molecules; in its ionic form it is influential on the pH of body fluids.|
|Nitrogen||An important structural component of all genetic material (nucleic acids).|
|Calcium||A building block of bones and teeth; its ionic form is essential in muscle contraction, impulse conduction in nerves, and blood clotting.|
|Phosphorus||Joins calcium to contribute to bone crystalline structure; present in nucleic acids and ATP.|
|Potassium||Its ionic form is the major cation (positive ions) in cells; necessary for conduction of nerve impulses and muscle contraction.|
|Sulfur||Important component of muscle proteins|
|Chlorine||In ionic form is the most abundant anion (negative ion) outside the cell.|
|Magnesium||Found in bone and plays an important assisting role in many metabolic functions.|
|Iodine||Required in thyroid hormones which are the body's main metabolic hormones.|
|Iron||Basic building block of the hemoglobin molecule which is a major transporter of oxygen in body.|
|The following elements are referred to as trace elements because they are required to in very minute amounts. They are, however, important elements found as part of enzymes or are required for enzyme activation.|
|Chromium||Promotes glucose metabolism; helps regulate blood sugar.|
|Cobalt||Promotes normal red-blood cell formation.|
|Copper||Promotes normal red-blood cell formation; acts as a catalyst in storage and formation; acts as a catalyst in storage and release of iron to form hemoglobin; promotes connective tissue formation and central nervous system function.|
|Fluorine||Prevents dental caries|
|Manganese||Promotes normal growth and development; promotes cell function; helps many body enzymes generate energy.|
|Molybedenum||Promotes normal growth and development and cell function.|
|Selenium||Complements Vitamin E to act as an efficient anti-oxidant.|
|Vanadium||Plays role in metabolism of bones and teeth.|
|Zinc||Maintains normal taste and smell; aids wound healing; helps synthesize DNA and RNA.|