Chapter 2: Chemistry Foundations for Anatomy & Physiology

Chemistry and Matter in Anatomy & Physiology

Introduction to Matter and Chemistry

Chemistry is fundamental to understanding the structure and function of the human body. Matter is anything that has mass and occupies space, and it exists in three states: solid, liquid, and gas. Chemistry is the study of matter and its interactions, which underpins all physiological processes.

• Matter: Anything that has mass and occupies space; can be solid, liquid, or gas.

• Chemistry: The scientific study of matter and how substances interact and change.

Atoms and Atomic Structure

Basic Atomic Structure

Atoms are the smallest units of matter that retain the properties of an element. They are composed of subatomic particles: protons, neutrons, and electrons.

• Atom: Smallest unit of matter retaining original properties.

• Subatomic particles:

  • Protons (p+): Positively charged, located in the nucleus.

  • Neutrons (n): No charge, slightly larger than protons, located in the nucleus.

  • Electrons (e-): Negatively charged, found outside the nucleus in electron shells.

• Atoms are electrically neutral when the number of protons equals the number of electrons.

Example: A carbon atom has 6 protons, 6 neutrons, and 6 electrons.

Electron Shells

Electrons are arranged in shells around the nucleus. Each shell can hold a specific number of electrons:

• 1st shell: 2 electrons

• 2nd shell: 8 electrons

• 3rd shell: 18 electrons (satisfied with 8 in most biological contexts)

Valence electrons in the outermost shell determine chemical reactivity.

Elements and the Periodic Table

Atomic Number and Elements

The atomic number is the number of protons in the nucleus and defines each element. Elements are substances that cannot be broken down into simpler substances by chemical means.

• Atomic number: Number of protons in the nucleus.

• Element: Substance made of atoms with the same number of protons.

The Periodic Table

The periodic table organizes elements by increasing atomic number and groups them by shared properties. Each element is represented by a chemical symbol.

• Groups: Columns of elements with similar properties.

• Chemical symbol: One- or two-letter abbreviation for each element (e.g., H for hydrogen, O for oxygen).

Elements in the Human Body

The human body is primarily composed of four major elements, with additional mineral and trace elements essential for health.

• Major elements (96%): Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N)

• Mineral elements (<4%): Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg), Phosphorus (P), Sulfur (S), Chlorine (Cl)

• Trace elements (0.01%): Iron (Fe), Iodine (I), Zinc (Zn), Copper (Cu), Selenium (Se), Manganese (Mn), Fluorine (F)

Element Type	Examples	Role in Body
Major Elements	O, C, H, N	Structural and functional components of biomolecules
Mineral Elements	Na, K, Ca, Mg, P, S, Cl	Electrolyte balance, bone structure, enzyme function
Trace Elements	Fe, I, Zn, Cu, Se, Mn, F	Enzyme cofactors, hormone production

Additional info: The periodic table is a foundational tool in chemistry and biology, helping to predict element behavior and interactions in physiological processes.