Question

A national project on "Physiology Across the Curriculum" has identified gradient driven flow as one of the critical principles that physiology students need to know, understand, and master. Gradient driven flow means that the transport of something through space occurs as a result of a change in some variable over location in space — concentration, pressure, temperature, voltage,…. In this class we've studied two gradient driven flow equations: Fick's law and the Hagen-Poiseuille equation. Pick one, describe what it tells us, and discuss what value understanding it has for making sense of something in biology. Note: Your answer will be judged not solely on its correctness, but for its depth, coherence, and clarity.

Answer 1

According to Fick's law,

If the concentration of a solute in one region is greater than in another of a solution,the solute diffuses from the region of higher concentration to the region of lower concentration and the rate of diffusion is proportional to the concentration gradient.

Diffusion flux,J = - D dC/dX

Where D is diffusion coefficient

C is concentration and X is position.

In biology diffusion is seen in various cases.

For example, exchange of gases oxygen and Carbon dioxide occurs by diffusion. At tissue level, oxygen concentration is less ,and at lung level oxygen concentration is more compared to tissue therefore oxygen is transported from lung level lo tissue level,thus useful for tissues in oxygen supply.

Carbon dioxide concentration is more at tissue level compared to lung level, therefore carbon dioxide is transported from tissues to lungs.

At lung _atmosphere level,

Oxygen concentration is more in atmosphere compared to lungs,therefore oxygen is inspired in and Carbon dioxide concentration is more at lung region compared to atmosphere, therefore carbon dioxide is expired out.

Thus ficks law plays an important role in exchange of gases carbon dioxide and oxygen in human body helping in respiration.

Diffusion is also important for transport of many important things like glucose and amino acids produced from digested food from intestine to blood to the cells,down the concentration gradient by diffusion.