Chapter 2: Chemistry Comes Alive – Foundations for Anatomy & Physiology

Chapter 2: Chemistry Comes Alive

Matter

Matter is a fundamental concept in chemistry and biology, referring to anything that occupies space and has mass. Understanding matter is essential for studying the structure and function of the human body.

• Definition: Matter is anything that has mass (weight) and occupies space.

• States of Matter:

  • Solid: Definite shape and volume.

  • Liquid: Definite volume, changeable shape.

  • Gas: Changeable shape and volume.

• Example: Bones are solids, blood is a liquid, and oxygen in the lungs is a gas.

Energy

Energy is the capacity to do work or put matter into motion. All physiological processes require energy, which exists in various forms within the body.

• Kinetic Energy: Energy in action; for example, muscle contraction.

• Potential Energy: Stored (inactive) energy; for example, energy stored in chemical bonds.

• Conversion: Potential energy becomes kinetic energy when released.

Forms of Energy

Energy in biological systems can be classified into several forms, each playing a role in maintaining life.

• Chemical Energy: Stored in bonds of chemical substances (e.g., ATP).

• Electrical Energy: Results from movement of charged particles (e.g., ions across cell membranes).

• Mechanical Energy: Directly involved in moving matter (e.g., muscle movement).

• Radiant or Electromagnetic Energy: Exhibits wavelike properties (e.g., visible light, ultraviolet light, X-rays).

Energy Form Conversions

Energy can be converted from one form to another in the body, but these conversions are not perfectly efficient.

• Example: Food is converted to ATP (adenosine triphosphate), the energy currency of cells.

• Inefficiency: Some energy is "lost" as heat during conversion, such as heat produced when muscles contract.

Atoms and Atomic Structure

Atoms

Atoms are the smallest stable units of matter and the building blocks of all substances, including those in the human body.

• Subatomic Particles:

  • Protons (p+): Positive electrical charge, located in the nucleus.

  • Neutrons (n0): Electrically neutral, located in the nucleus.

  • Electrons (e-): Negative electrical charge, whirl around the nucleus in the electron cloud.

• Atomic Structure:

  • Nucleus: Central part of the atom containing protons and neutrons.

  • Electron Cloud: Region surrounding the nucleus where electrons are found.

  • Neutrality: Number of electrons equals number of protons in a neutral atom.

Atomic Models

Atomic structure can be represented in different models to illustrate the arrangement of subatomic particles.

• Orbital Model: Electrons are shown as a cloud of negative charge around the nucleus.

• Simplified Model: Electrons are depicted as small spheres orbiting the nucleus.

Table: Subatomic Particles

Particle	Symbol	Charge	Location
Proton	p+	+1	Nucleus
Neutron	n0	0	Nucleus
Electron	e-	-1	Electron cloud

Example: A hydrogen atom has 1 proton, 0 neutrons, and 1 electron.

Additional info: Understanding atomic structure is essential for grasping how atoms interact to form molecules, which are the basis of all biological processes.