Chemistry Foundations for Anatomy & Physiology

Chemistry in Anatomy & Physiology

Importance of Chemistry in A&P

Chemistry provides the foundational knowledge necessary to understand physiological processes at the molecular and cellular levels. Many biological functions depend on chemical interactions and reactions.

• Biochemical reactions underlie metabolism, cellular communication, and energy production.

• Understanding chemical principles helps explain the structure and function of tissues and organs.

Chemistry Basics

Matter and Its States

Matter is anything that occupies space and has mass. Chemistry studies the nature of matter, its physical changes, and chemical changes.

• States of Matter:

  1. Solid – Definite shape and volume; particles are tightly packed.

  2. Liquid – Definite volume, no definite shape; particles are less tightly packed and can move past each other.

  3. Gas – No definite shape or volume; particles are far apart and move freely.

Table: Properties of States of Matter

State	Shape	Volume	Particle Arrangement
Solid	Definite	Definite	Tightly packed
Liquid	Indefinite	Definite	Loosely packed
Gas	Indefinite	Indefinite	Far apart

Elements and Atoms

All matter is composed of elements, which are substances that cannot be broken down by chemical means. The smallest unit of an element is the atom.

• Elements: Pure substances made of only one kind of atom.

• Atoms: Consist of a nucleus (protons and neutrons) and electrons orbiting the nucleus.

• Subatomic particles:

  • Proton – positive charge

  • Neutron – no charge

  • Electron – negative charge

Ions and Electrolytes

An ion is an atom that has gained or lost electrons, resulting in a net electrical charge. Electrolytes are substances that release ions in water and conduct electricity.

• Cation: Positively charged ion (loss of electrons)

• Anion: Negatively charged ion (gain of electrons)

• Electrolytes: Essential for nerve impulse transmission and muscle contraction

Molecules and Compounds

Definitions and Differences

A molecule is formed when two or more atoms bond together. A compound is a molecule that contains atoms of different elements.

• Molecule: O2, H2

• Compound: H2O, CO2

Molecular Formulas

Molecular formulas show the elements present and the number of each atom in a molecule.

• Examples: $C_6H_{12}O_6$, $H_2O$

Chemical Bonds

Bonding of Atoms

Bonds form when atoms combine with other atoms to achieve stability.

• Ionic Bond: Electrons are transferred from one atom to another, forming cations and anions. Example: $Na^+ + Cl^- ightarrow NaCl$

• Covalent Bond: Atoms share electrons. Example: $O = O$ (oxygen molecule)

• Hydrogen Bond: Weak attraction between the positive end of one polar molecule and the negative end of another. Important in water and nucleic acid structure.

Chemical Reactions

Types of Chemical Reactions

Chemical reactions occur when chemical bonds form or break among atoms, ions, or molecules.

• Synthesis Reaction: Two or more simple substances combine to form a complex substance. $A + B ightarrow AB$

• Decomposition Reaction: A complex substance breaks down into simpler substances. $AB ightarrow A + B$

• Exchange Reaction: Parts of two molecules are exchanged. $AB + CD ightarrow AD + CB$

• Reversible Reaction: Products can change back to reactants. $A + B ightleftharpoons AB$

Mixtures and Biochemistry

Mixtures

Mixtures are combinations of two or more substances that are not chemically bonded.

• Solutions: Homogeneous mixtures where solutes are dissolved in solvents.

• Colloids: Mixtures with larger particles that do not settle out.

• Suspensions: Heterogeneous mixtures with large particles that settle out over time.

Biochemistry

Biochemistry is the study of the composition of living matter, focusing on organic and inorganic compounds.

• Organic compounds: Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids.

• Inorganic compounds: Generally do not contain carbon; include water, salts, acids, and bases.

Organic Compounds

Carbohydrates

Carbohydrates are sugars and starches composed of carbon, hydrogen, and oxygen (C, H, O). They serve as a primary energy source.

• Monosaccharides: Simple sugars; examples include glucose, fructose, and galactose.

• Disaccharides: Two monosaccharides joined; examples include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).

Lipids

Lipids are organic molecules with more carbon and hydrogen than oxygen. They are mostly insoluble in water and serve as energy storage and structural components.

• Triglycerides: Most common lipid; composed of glycerol and three fatty acids.

• Phospholipids: Composed of glycerol, two fatty acids, and a phosphate group; major component of cell membranes.

Nucleic Acids

Nucleic acids are the largest biological molecules, containing C, H, O, N, and P. They store genetic information.

• Structure: Made of nucleotides (pentose sugar, nitrogen base, phosphate group).

• Types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Table: Comparison of DNA and RNA

Feature	DNA	RNA
Pentose Sugar	Deoxyribose	Ribose
Bases	A, T, C, G	A, U, C, G
Strands	Double-stranded (helix)	Single-stranded

Deoxyribonucleic Acid (DNA)

DNA is a double-stranded helical molecule that stores genetic information and directs cellular activities. Its structure allows for replication and transmission of genetic information.

• Base pairing: Adenine pairs with thymine, cytosine pairs with guanine.

• Function: Provides instructions for protein synthesis and cellular function.

Summary Table: Major Organic Molecules

Type	Elements	Function	Examples
Carbohydrates	C, H, O	Energy source	Glucose, starch
Lipids	C, H, O	Energy storage, cell membranes	Triglycerides, phospholipids
Proteins	C, H, O, N, S	Structure, enzymes	Hemoglobin, enzymes
Nucleic Acids	C, H, O, N, P	Genetic information	DNA, RNA

Additional info: Proteins are mentioned in the context of organic molecules but not detailed in the slides; they are included here for completeness.