Human body isotonic solution

Sports drinks provide water to the body in the form of an isotonic solution (one having the same total molar concentration of solutes as human blood). These drinks contain electrolytes such as NaCI and KCI as well as sugar and... 

Osmotic pressure plays an important role in biological chemistry because the cells of the human body are encased in semipermeable membranes and bathed in body fluids. Under normal physiological conditions, the body fluid outside the cells has the same total solute molarity as the fluid inside the cells, and there is no net osmosis across cell membranes. Solutions with the same solute molarity are called isotonic solutions. 

Essentiality and Toxicity for Man For humans, sodium (and chlorine) are essential nutrients, the deficiency of which frequently and acutely leads to premature death, usually from circulatory failure. The second most frequent consequence is diarrhea. The physiology of man is, consequently, characterized by multiple control mechanisms which act to maintain and control the NaCl content and concentrations within the body. Sodium deficiency symptoms in humans are not well known nonetheless, a sodium chloride deficit as a common cause of death is quite treatable with minimum effort, provided that some basic principles are remembered. Body weight change is the best indicator of a sodium deficit. Except in the presence of imminent circulatory collapse, oral treatment is usually possible. Except in case of cholera, the colon usually responds to aldosterone, and quite low sodium concentrations are adequate for the rehydration solutions. In the case of cholera, near-isotonic solutions are necessary (Harper et al. 1997). 

The human body contains 60% water, which is an excellent solvent for electrolytes and plasma proteins [8], Because all cell membranes are freely permeable to water, intra- and extracellular fluids are generally considered to be in osmotic equilibrium. Therefore, the osmolality (the total molality of individual ionic and neutral solute species that contribute to the osmotic pressure) of the extracellular fluid is approximately equal to that of the intracellular fluid (ICF) and hence plasma osmolality is a guide to intracellular osmolality. Normal osmolality in plasma is —0.30 osmoles (kg water) F This is contributed mainly by sodium, chloride, potassium, urea and glucose, and additionally by other ions and substances in the blood. Most of the body fluids are isotonic ( of equal osmotic pressure , when only imperme-ant solutes are taken into account), with the notable exceptions of urine, sweat and saliva [9]. 

Human blood is a complex mixture with a variety of functions provided by four major components red and white blood cells, platelets, and plasma. When a person begins to lose blood rapidly, the body can survive for at least a short time without the white blood cells (which are needed only to stave off infection), the platelets (of which there are large excesses in the body), and plasma (which can he replaced by an isotonic fluid, such as saline or Ringer s solution). But life cannot continue long with a replacement for the red blood cells. These are the cells that carry oxygen from the lungs to other cells, where it is used to carry out the metabolic processes that keep the body alive. 

Sodium chloride is a component of all body fluids, including tears. A solution of 0.9% is approximately isotonic with tears. Of the various concentrations tested, 2% to 5% formulations have proven effective, with an irritation level acceptable to most patients. Studies comparing various hyperosmotic agents in human subjects have confirmed the usefulness of hypertonic sodium chloride in the treatment of corneal edema. Use of 5% sodium chloride in ointment form can be effective in reducing corneal thickness and in improving vision.The maximum reduction in corneal thickness occurs 3 to 4 hours after instillation of the ointment (Figure 15-1). 

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