Chemistry in Anatomy & Physiology

Introduction to Chemistry

Chemistry is the study of matter and its interactions, which is fundamental to understanding biological processes in the human body. Matter and energy are the two basic components that underlie all physiological functions.

• Matter: Anything that has mass and occupies space. Exists in three states: solid, liquid, and gas.

• Energy: The capacity to do work or cause change. Energy exists as kinetic energy (energy of motion) and potential energy (stored energy).

Forms of Energy in the Human Body

Energy is essential for physiological processes. The body utilizes several forms of energy:

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

• Electrical energy: Movement of charged particles, crucial for nerve impulses.

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

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

• Heat: Byproduct of energy conversion, helps maintain body temperature.

Composition of Matter

Elements and the Periodic Table

Elements are pure substances that cannot be broken down by ordinary chemical means. Each element has unique physical and chemical properties and is represented on the Periodic Table of Elements.

• Major elements in the human body: Oxygen, Carbon, Hydrogen, Nitrogen.

• Mineral elements: Calcium, Phosphorus, Potassium, Sulfur, Sodium, Chlorine, Magnesium, Iodine, Iron.

• Trace elements: Chromium, Manganese, Zinc.

Periodic Table Details

Each element on the periodic table is identified by:

• Atomic number: Number of protons in the nucleus.

• Elemental symbol: One or two-letter abbreviation.

• Element name

• Atomic weight: Average mass of atoms of the element.

Example: Carbon (C) has atomic number 6 and atomic weight 12.01.

Atomic Structure

Atoms and Subatomic Particles

Atoms are the smallest units of elements, composed of subatomic particles:

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

• Neutrons (n0): No charge, found in the nucleus.

• Electrons (e-): Negatively charged, orbit the nucleus in shells.

Atomic number equals the number of protons (and electrons in a neutral atom). Mass number is the sum of protons and neutrons.

Isotopes are variants of elements with different numbers of neutrons.

Orbital Model of the Atom

Electrons occupy regions called orbitals or shells around the nucleus. The outermost shell is the valence shell, which determines chemical reactivity.

• Valence electrons: Electrons in the outermost shell, involved in bonding.

• Octet rule: Atoms tend to gain, lose, or share electrons to achieve 8 electrons in their valence shell.

Example: A carbon atom has 6 protons, 6 neutrons, and 6 electrons (2 in the first shell, 4 in the second shell).

*Additional info: The notes provide foundational chemistry concepts essential for understanding molecular and cellular processes in Anatomy & Physiology. These principles underlie topics such as metabolism, cellular structure, and physiological regulation.*