Question

1. Fick’s Law: define it and list examples where evolution has selected for traits that enhance diffusion

2. Intrinsic and extrinsic control mechanisms – provide examples in two tissues

Answer 1

1. Fick’s law of diffusion describes diffusion, which was derived by Adolf Fick in 1855, used to solve the diffusion coefficient, D. Which states two laws;

1. The molar flux is proportional to the concentration gradient.

2. The rate of concentration change at a point in space is proportional to the second derivative of concentration with space.

        Examples:

1. Brownian particle and Mean squared displacement

2. Constant concentration source and Diffusion length

2.Intrinsic controlled system: An intrinsic controlled system is inherent in an organ, where the organ is capable of maintaining homeostasis within itself.

For example- The heart can control its own heart rate.

Extrinsic controlled system: Extrinsic control systems are the nervous and endocrine systems, which exist outside of the organs they control, and these systems can override intrinsic systems.

For example- Although the heart control its own rate, a slamming door will prompt the nervous system to increase the heart rate externally.