Diffusion

Diffusion (di-fuczhun) (also called simple diffusion) is the tendency of atoms, molecules, and ions in a liquid or air solution to move from areas of higher concentration to areas of lower concentration, thus becoming more evenly distributed, or more diffuse. Diffusion occurs because atoms, molecules, and ions are in constant motion. Each particle travels in a separate path along a straight line until it collides with some other particle and bounces off. Then it moves in its new direction until it collides again and changes direction once more. Because collisions are less likely if there are fewer particles, there is a net movement of particles from an area of higher concentration to an area of lower concentration. This difference in concentrations is called a concentration gradient, and atoms, molecules, and ions are said to diffuse down a concentration gradient. With time, the concentration of a given substance becomes uniform throughout a solution.

Cell membrane

Mitochondrion

Rough Nucleus endoplasmic reticulum

Cell membrane

Mitochondrion

Diffusion Blood

Microtubule

Microfilament

Microtubule

Microfilament

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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