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Isotonic in Biology

Published in Biology & Mathematics 2 mins read

What is Isotonic?

Isotonic refers to two related but distinct concepts: one in biology and the other in mathematics.

In biology, "isotonic" describes a solution having the same osmotic pressure as another solution, typically referring to the osmotic pressure inside a cell. This means there's no net movement of water across a semipermeable membrane separating the two solutions.

  • Example: A red blood cell placed in an isotonic solution will maintain its normal shape and size because there's no water influx or efflux. Conversely, a cell in a hypotonic solution (lower solute concentration) will swell and potentially burst (lysis), while a cell in a hypertonic solution (higher solute concentration) will shrink (crenation).

  • Reference: As stated in the provided text from StatPearls, "An isotonic solution has the same solute concentration compared to the intracellular solute concentration. When a red blood cell is placed in an isotonic environment..."

Isotonic in Physiology (Muscle Contraction)

In physiology, isotonic refers to a type of muscle contraction where the muscle changes length while maintaining relatively constant tension. This is in contrast to isometric contractions, where muscle length remains constant while tension changes.

  • Types of Isotonic Contractions: Isotonic contractions can be further classified as concentric (muscle shortens) and eccentric (muscle lengthens).
  • Reference: The Merriam-Webster definition states, "of, relating to, or being muscular contraction in the absence of significant resistance, with marked shortening of muscle fibers, and without great increase in muscle tone compare isometric." This directly addresses isotonic muscle contractions.

Isotonic in Mathematics (Isotonic Regression)

In mathematics, specifically in statistics and numerical analysis, isotonic regression refers to a technique for fitting a non-decreasing function to data. This is used when there's reason to believe that the underlying relationship between variables is monotonic (always increasing or always decreasing).

  • Reference: The scikit-learn documentation on isotonic regression describes it as fitting "a non-decreasing real function to 1-dimensional data."