Part I: Chemistry Comes Alive

Introduction

• Chemistry is fundamental to understanding Anatomy & Physiology, as all biological processes are based on chemical interactions. This chapter introduces the essential chemical principles underlying the structure and function of the human body.

Matter and Energy

Matter

Matter is the substance of the universe and forms the basis of all living and non-living things.

• Definition: Anything that has mass and occupies space.

• States of Matter:

  • Solid: Has a definite shape and volume.

  • Liquid: Has volume but conforms to the shape of its container.

  • Gas: Has neither definite shape nor volume.

• Mass: The measure of the amount of matter in an object.

Energy

Energy is required for all physiological processes, from muscle contraction to nerve impulse transmission.

• Definition: The capacity to do work or put matter into motion.

• Energy does not have mass and does not occupy space.

• The more work done, the more energy is used.

• Exists in two basic forms:

  • Kinetic Energy: Energy in action or motion.

  • Potential Energy: Stored (inactive) energy that can be released to do work.

• Transformation: Energy can be transformed from one form to another, but cannot be created or destroyed (Law of Conservation of Energy).

Types of Energy in Biological Systems

• Chemical Energy: Stored in bonds of chemical substances; released during chemical reactions.

• Electrical Energy: Results from movement of charged particles; essential for nerve impulse transmission.

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

• Radiant or Electromagnetic Energy: Travels in waves (e.g., heat, visible light, ultraviolet light).

Example: Turning on a lamp converts electrical energy to light energy.

Additional info: In the human body, energy conversions are never 100% efficient; some energy is always lost as heat, which helps maintain body temperature.

Properties of Elements

Elements

Elements are the simplest forms of matter and are essential for life.

• Definition: Substances that cannot be broken down into simpler substances by ordinary chemical methods.

• Major Elements of the Human Body (96% of body weight):

  • Carbon (C)

  • Oxygen (O)

  • Hydrogen (H)

  • Nitrogen (N)

• Lesser Elements (3.9%): Calcium, Phosphorus, Potassium, Sulfur, Sodium, Chlorine, Magnesium, Iron

• Trace Elements (<0.01%): Required in minute amounts; essential for enzyme function and other processes.

• Periodic Table: Lists all known elements; each element is represented by an atomic symbol (e.g., "O" for oxygen, "Na" for sodium).

Atoms

Atoms are the building blocks of elements and retain the properties of the element.

• Definition: The smallest unit of matter retaining the properties of an element.

• Each atom is given an atomic symbol (usually one or two letters).

• Atomic symbols may derive from Latin names (e.g., "Na" for sodium from natrium).

Summary Table: Major Elements in the Human Body

Additional info: Trace elements such as zinc, copper, and iodine are vital for specific biochemical reactions and hormone production.