How Do I Define Cell Tonicity?

To define cell tonicity, it is helpful to understand osmosis and the behavior of cells in a liquid environment. When you have two solutions separated by a semipermeable membrane, tonicity refers to the measurement of osmotic pressure of those two solutions. The definition of tonicity is often misunderstood in the medical context, because the application of the term applies in several different ways. The most common and considered the most useful definition maintained by the Anaesthesia Education Website, establishes that tonicity is the effective osmolality, equal to the addition of all solute concentrates, exerting influence on the entire osmotic pressure on the membrane.

Instructions

• 1

  You can describe the concept of osmosis as the spreading of water across a semipermeable cell membrane, going from a high concentration to a low concentration of water potential. The process of osmosis has the primary function of carrying water in and out of the cell. This helps the cell sustain itself.

• 2

  Tonicity describes the behavior of cells in a liquid environment with particular emphasis on how particles dissolved in those environments affect the organism in the environment. In most basic terms, tonicity refers to the measurement of osmotic pressure preventing the inward flow of water across the semipermeable membrane.

• 3

  The three types of tonicity are isotonic, hypertonic, and hypotonic. Isotonicity refers to equal concentrations of impermeable solutions on both sides of the membrane, while hypertonicity refers to greatest concentration of impermeable solutes on either side of the membrane. Hypotonicity refers to the lesser concentration of impermeable solutions on either side of the membrane.

• 4

  Hypotonic cells tend to swell and burst because the cells draw in too much water, while cells in a hypertonic environment tend to shrink and distort, because the cells push out too much water. Cells in an isotonic state tend to function with stability.