Chemistry Foundations for Anatomy & Physiology

Chemistry in Anatomy and Physiology

Importance of Chemistry

Chemistry is fundamental to understanding anatomy and physiology because bodily functions depend on chemical reactions. Cellular functions and physiological processes are intricately tied to these reactions, and biochemistry is essential in diagnosing and treating diseases.

• Bodily functions rely on chemical reactions for metabolism, signaling, and homeostasis.

• Cellular processes such as respiration, protein synthesis, and energy production are chemical in nature.

• Biochemistry underpins medical treatments and diagnostics.

Basic Terminology

Matter

Matter is anything that has mass and occupies space. It is the physical substance of the universe, including all living and nonliving things.

• Mass is the amount of matter in an object; it is not the same as weight, which is mass under the influence of gravity.

• States of matter: Solid, liquid, and gas.

• Example: Red blood cells are matter found in blood.

Energy

Energy is the capacity to do work or cause change. It exists in different forms and states within biological systems.

• Kinetic energy: Energy of motion.

• Potential energy: Stored energy due to position or structure.

• Forms of energy:

  • Chemical energy: Stored in chemical bonds.

  • Electrical energy: Movement of charged particles.

  • Mechanical energy: Directly involved in moving matter.

  • Radiant/Electromagnetic energy: Energy that travels in waves (e.g., light).

• Energy conversions often produce heat as a byproduct.

Atoms, Elements, Molecules, and Compounds

Understanding the building blocks of matter is essential for studying physiology.

• Atoms: The smallest units of matter that retain the properties of an element.

• Elements: Pure substances composed of only one type of atom. Classified as:

  • Bulk elements: Present in large amounts (e.g., oxygen, carbon).

  • Lesser elements: Present in smaller amounts but still essential (e.g., calcium, potassium).

  • Trace elements: Required in minute quantities (e.g., iron, iodine).

• Molecules: Two or more atoms bonded together (e.g., O2).

• Compounds: Molecules composed of two or more different elements (e.g., H2O).

Common Elements in the Human Body

Elemental Composition and Functions

The human body is composed of several key elements, each with specific biological roles.

Element	Atomic Symbol	Approx. % Body Mass	Functions
Oxygen	O	65.0	Major component of organic and inorganic molecules; required for cellular energy (ATP) production.
Carbon	C	18.5	Primary component of all organic molecules (carbohydrates, lipids, proteins, nucleic acids).
Hydrogen	H	9.5	Component of all organic molecules; influences pH as an ion (proton).
Nitrogen	N	3.2	Component of proteins and nucleic acids (genetic material).
Calcium	Ca	1.5	Found in bones and teeth; required for muscle contraction, nerve impulses, and blood clotting.
Phosphorus	P	1.0	Part of nucleic acids and ATP; important for bone and teeth structure.
Potassium	K	0.4	Major positive ion inside cells; necessary for nerve impulse transmission and muscle contraction.
Sulfur	S	0.3	Component of proteins, especially muscle proteins.
Sodium	Na	0.2	Major positive ion outside cells; important for water balance, nerve impulses, and muscle contraction.
Chlorine	Cl	0.2	Most abundant negative ion outside cells; maintains water balance and is involved in nerve function.
Magnesium	Mg	0.1	Present in bones; important for metabolic reactions.
Iron	Fe	Trace	Component of hemoglobin, which transports oxygen in blood.

Additional info: Trace elements such as iodine, fluorine, and zinc are required in very small amounts and are often part of enzymes or hormones.

Periodic Table

Organization and Use

The periodic table organizes elements by atomic number and chemical properties. It is a fundamental tool for understanding the composition and behavior of elements in biological systems.

• Atomic number: Number of protons in the nucleus of an atom.

• Atomic mass: Sum of protons and neutrons in the nucleus.

• Groups: Columns with similar chemical properties.

• Periods: Rows indicating increasing atomic number.

• Classification: Metals, metalloids, and nonmetals.

Example: Sodium (Na) and potassium (K) are both alkali metals essential for nerve function.