Topic 2: The Chemical Level of Organization

Matter and Energy

The study of anatomy and physiology requires an understanding of the chemical basis of life, including the nature of matter and energy. These concepts form the foundation for understanding cellular structure and function.

• Matter: Anything that occupies space and has mass.

• States of Matter:

  • Solid: Definite shape and volume.

  • Liquid: Definite volume; takes the shape of its container.

  • Gas: Neither a definite shape nor volume.

• Physical Changes: Changes that do not alter the basic nature of a substance (e.g., change of state from solid to liquid).

• Chemical Changes: Changes that alter the chemical composition of a substance, occurring through chemical reactions.

Energy

Energy is essential for all physiological processes. It is defined as the ability to do work and exists in various forms within the body.

• Energy: The ability to do work; has no mass and does not occupy space.

• Kinetic Energy: Energy in action; energy that is doing work.

• Potential Energy: Stored energy; energy that is inactive but has the potential to do work.

• Example: Climbing a diving board converts kinetic energy to potential energy, which is then converted back to kinetic energy when diving.

Additional info: Energy transformations are fundamental to metabolism and cellular function. The body uses chemical energy stored in molecules such as ATP to power physiological activities.