Chemistry Fundamentals for Anatomy & Physiology

The Importance of Chemistry in Anatomy and Physiology

Role of Chemistry in Anatomy & Physiology

Chemistry is foundational to understanding the structure and function of the human body. All anatomical structures and physiological processes are based on chemical reactions and the properties of substances.

• Chemistry studies the composition of substances and how they change in chemical reactions.

• The human body, food, and medications are all composed of chemicals.

• All body fluids are made up of water and electrolytes.

Fundamentals of Chemistry

Basic Definitions

Understanding basic chemical concepts is essential for studying anatomy and physiology.

• Matter: Anything that takes up space and has mass. Exists as solids, liquids, and gases.

• Mass: The amount of matter present in a substance.

• Weight: The heaviness of an object due to gravitational pull on its mass.

• Chemistry: The study of the composition, properties, and interactions of matter.

• Biochemistry: The branch of chemistry that studies physiological processes and diseases at the molecular level.

Elements and Atoms

Types and Roles of Elements

Elements are the simplest forms of matter with specific chemical properties. The human body requires different elements in varying amounts.

• Elements: Pure substances with unique chemical properties; 92 naturally occurring elements.

• Compounds: Chemical combinations of different elements.

• Atoms: The smallest particles of an element that retain its properties.

• Bulk elements: Needed in large amounts (e.g., C, O, H, N, S, P).

• Trace elements: Needed in small amounts (e.g., Fe, I).

• Ultratrace elements: Needed in very minute amounts (e.g., As).

Table: Some Particles of Matter

Name	Characteristic	Name	Characteristic
Atom	Smallest particle of an element with its properties	Neutron (n0)	Relatively large particle within atom; about the same weight as proton; uncharged and thus electrically neutral; found within atomic nucleus
Electron (e-)	Extremely small particle within an atom; almost no weight; carries a negative electrical charge and is in constant motion around an atomic nucleus	Ion	Particle, formed from an atom, that is electrically charged because it has gained or lost one or more electrons
Proton (p+)	Relatively large particle within an atom; carries a positive electrical charge and is found within an atomic nucleus	Molecule	Particle formed by the chemical union of two or more atoms

Table: Elements in the Human Body (By Weight)

Major Elements	Symbol	Approximate Percentage of the Human Body
Oxygen	O	65.0
Carbon	C	18.5
Hydrogen	H	9.5
Nitrogen	N	3.2
Calcium	Ca	1.5
Phosphorus	P	1.0
Potassium	K	0.4
Sulfur	S	0.3
Chlorine	Cl	0.2
Sodium	Na	0.2
Magnesium	Mg	0.1
Trace Elements
Cobalt	Co	less than 0.1%
Copper	Cu
Fluorine	F
Iodine	I
Iron	Fe
Manganese	Mn
Zinc	Zn

Atomic Structure

Subatomic Particles and Atomic Neutrality

Atoms are composed of three main subatomic particles, each with distinct properties and roles in chemical behavior.

• Protons: Large particles with a single positive charge; found in the nucleus.

• Neutrons: Large particles with no electrical charge; found in the nucleus.

• Electrons: Small particles with a single negative charge; move in constant motion around the nucleus.

• The nucleus contains protons and neutrons, while electrons orbit the nucleus.

• In a neutral atom, the number of protons equals the number of electrons.