Chemical Foundations of Anatomy & Physiology: Atoms, Elements, and Atomic Structure

Study Guide - Smart Notes

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Learning Outcomes

Overview

This section introduces the chemical principles essential for understanding anatomy and physiology. Students will learn about atomic structure, chemical bonding, the role of elements in the human body, and how these concepts underpin physiological processes.

Describe an atom and how atomic structure affects interactions between atoms.
Compare the ways in which atoms combine to form molecules and compounds.
Distinguish among the major types of chemical reactions important for physiology.
Explain the crucial role of enzymes in metabolism.
Distinguish between inorganic and organic compounds.
Explain how the chemical properties of water make life possible.

Introduction to the Chemical Level

Chemistry in Anatomy & Physiology

Chemistry is the science that deals with the structure of matter, which is fundamental to understanding physiological processes. The chemical level of organization includes:

Structure of atoms
Basic chemical building blocks
How atoms combine to form increasingly complex structures

Atoms and Atomic Structure

Matter and Atoms

Matter is anything that takes up space and has mass. All matter is composed of atoms, which are the smallest units of matter that retain the properties of an element.

Atoms join together to form chemicals with different characteristics.
Chemical characteristics determine physiology at molecular and cellular levels.

Subatomic Particles

Atoms are made up of three main subatomic particles:

Protons: Positive charge, 1 mass unit
Neutrons: Neutral, 1 mass unit
Electrons: Negative charge, very low mass

Atomic Structure

Atomic number: Number of protons in the nucleus; determines the element's identity.
Nucleus: Central region containing protons and neutrons.
Electron cloud: Spherical area surrounding the nucleus where electrons are found.
Electron shell: Two-dimensional representation of the electron cloud, showing energy levels.

Principal Elements in the Human Body

Major Elements and Their Significance

The human body is composed of several principal elements, each with specific physiological roles. The following tables summarize the most important elements by percentage of total body weight and their significance:

Element	% of Total Body Weight	Significance
Oxygen (O)	65.0	A component of water and other compounds; gaseous form is essential for respiration.
Carbon (C)	18.6	Found in all organic molecules.
Hydrogen (H)	9.7	A component of water and most other compounds in the body.
Nitrogen (N)	3.2	Found in proteins, nucleic acids, and other organic compounds.
Calcium (Ca)	1.8	Found in bones and teeth; important for membrane function, nerve impulses, muscle contraction, and blood clotting.
Phosphorus (P)	1.0	Found in bones and teeth, nucleic acids, and high-energy compounds.
Potassium (K)	0.4	Important for proper membrane function, nerve impulses, and muscle contraction.

Element	% of Total Body Weight	Significance
Sodium (Na)	0.2	Important for blood volume, membrane function, nerve impulses, and muscle contraction.
Chlorine (Cl)	0.2	Important for blood volume, membrane function, and water absorption.
Magnesium (Mg)	0.06	A cofactor for many enzymes.
Sulfur (S)	0.04	Found in many proteins.
Iron (Fe)	0.007	Essential for oxygen transport and energy capture.
Iodine (I)	0.002	A component of hormones of the thyroid gland.
Trace elements	—	Includes silicon (Si), fluorine (F), copper (Cu), zinc (Zn), selenium (Se), cobalt (Co), manganese (Mn), cadmium (Cd), chromium (Cr), tin (Sn), boron (B), and vanadium (V). Some function as cofactors; the functions of many trace elements are poorly understood.

Atomic Models

Atoms consist of a dense nucleus (containing protons and neutrons) surrounded by an electron cloud. The electron cloud represents the probable locations of electrons.

Example: Hydrogen Isotopes

Hydrogen-1: Nucleus contains 1 proton, no neutrons.
Hydrogen-2 (Deuterium): Nucleus contains 1 proton and 1 neutron.
Hydrogen-3 (Tritium): Nucleus contains 1 proton and 2 neutrons.

Isotopes are atoms of the same element with different numbers of neutrons, affecting their mass but not their chemical properties.

Key Terms

Atom: The smallest unit of an element that retains its chemical properties.
Element: A pure substance composed of only one kind of atom.
Isotope: Atoms of the same element with different numbers of neutrons.
Atomic number: Number of protons in the nucleus.
Mass number: Number of protons plus neutrons in the nucleus.

Applications in Physiology

Understanding atomic structure is essential for grasping how elements interact in biological systems.
Principal elements are involved in processes such as respiration, nerve signaling, muscle contraction, and enzyme function.
Isotopes (e.g., radioactive isotopes) are used in medical imaging and research.

Example Equation: Atomic Mass Calculation

The atomic mass of an element is calculated as:

Additional info:

Trace elements, though present in minute quantities, can be critical for enzyme function and metabolic processes.
Radioisotopes are used in diagnostic imaging (e.g., PET scans) and cancer treatment.