Chemistry Foundations for Anatomy & Physiology

Chemistry in Anatomy & Physiology

Importance of Chemistry in A&P

Chemistry is fundamental to understanding physiological processes in the human body, including movement, digestion, and heart function. All physiological processes rely on chemical reactions.

• Chemical reactions drive essential body functions.

• Examples: muscle contraction, nutrient breakdown, nerve signaling.

States of Matter

Classification of Matter

Matter exists in three primary states, each with distinct properties relevant to biological systems.

• Solid: Definite shape and volume. Examples: Bones, teeth.

• Liquid: Definite volume but shape changes. Examples: Blood plasma, water.

• Gas: No definite shape or volume. Examples: Oxygen, carbon dioxide.

Atomic Structure

Components of Atoms

Atoms are the basic units of matter, composed of subatomic particles.

• Protons: Positively charged, found in the nucleus.

• Neutrons: No charge, found in the nucleus.

• Electrons: Negatively charged, orbit the nucleus.

• Atomic number: Number of protons.

• Mass number: Number of protons plus neutrons.

Electron Shells and Energy Levels

Electrons occupy energy levels or shells around the nucleus, influencing chemical bonding.

• First shell: 2 electrons.

• Second shell: 8 electrons.

• Electrons in outer shells determine chemical reactivity.

• Electrons are too small to count directly.

Chemical Bonding

Types of Chemical Bonds

Atoms interact through chemical bonds, which are essential for forming molecules.

• Ionic bonds: Transfer of electrons from one atom to another, resulting in charged ions.

• Covalent bonds: Sharing of electrons between atoms.

• Hydrogen bonds: Weak attractions between polar molecules, important in water and biological macromolecules.

Bond Polarity and Electronegativity

Bond polarity depends on the difference in electronegativity between atoms.

• Polar covalent bonds: Unequal sharing of electrons (e.g., water).

• Nonpolar covalent bonds: Equal sharing of electrons.

Water and Its Properties

Importance of Water in the Body

Water is the most abundant compound in living organisms and is essential for life.

• High heat capacity: Absorbs and releases heat slowly, helping maintain temperature homeostasis.

• High heat of vaporization: Requires significant energy to change from liquid to gas.

• Polarity: Allows water to dissolve ionic and polar substances.

• Cohesion: Water molecules stick together, important for transport in the body.

Types of Chemical Reactions

Major Reaction Types

Chemical reactions in the body involve the making and breaking of chemical bonds.

• Synthesis reaction: Atoms or molecules combine to form larger molecules. Example: $A + B ightarrow AB$

• Decomposition reaction: Molecules are broken down into smaller components. Example: $AB ightarrow A + B$

• Exchange reaction: Bonds are both made and broken; atoms are exchanged between molecules. Example: $AB + CD ightarrow AC + BD$

• Redox reactions: Involve the transfer of electrons between reactants.

Organic and Inorganic Compounds

Classification

Compounds in the body are classified as organic or inorganic.

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

• Inorganic compounds: Do not contain carbon (exceptions: carbon dioxide, carbon monoxide).

• Examples of inorganic compounds: Water, salts, acids, bases.

Acids, Bases, and Salts

Definitions and Functions

Acids, bases, and salts are important for maintaining pH and electrolyte balance in the body.

• Acids: Release hydrogen ions ($H^+$) in solution; proton donors.

• Bases: Accept hydrogen ions; proton acceptors.

• Salts: Ionic compounds that dissociate into ions in water; important for nerve impulse transmission and muscle contraction.

Macromolecules in Living Systems

Carbohydrates

Carbohydrates are organic molecules that serve as a major energy source for cells.

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined together (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., glycogen, starch).

Lipids

Lipids are hydrophobic molecules important for energy storage, insulation, and cell membrane structure.

• Triglycerides: Composed of fatty acids and glycerol.

• Phospholipids: Major component of cell membranes; have hydrophilic and hydrophobic regions.

• Steroids: Include cholesterol, which is important for membrane structure and hormone synthesis.

Proteins

Proteins are polymers of amino acids that perform a wide variety of functions in the body.

• Structure: Collagen provides support and tensile strength.

• Enzymes: Biological catalysts that accelerate chemical reactions.

• Transport: Hemoglobin transports oxygen in the blood.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA: Contains genetic instructions for protein synthesis.

• RNA: Involved in protein synthesis (messenger RNA, ribosomal RNA, transfer RNA).

ATP and Cellular Energy

Role of ATP

Adenosine triphosphate (ATP) is the primary energy carrier in cells.

• ATP stores energy in its phosphate bonds.

• Energy is released when ATP is hydrolyzed to ADP (adenosine diphosphate).

• ATP is essential for muscle contraction, nerve impulse transmission, and biosynthesis.

Summary Table: Key Chemical Concepts in A&P

Concept	Definition	Example/Application
Atom	Smallest unit of matter	Hydrogen atom
Molecule	Two or more atoms bonded together	Water (H2O)
Ionic Bond	Transfer of electrons	NaCl (table salt)
Covalent Bond	Sharing of electrons	O2 (oxygen gas)
Hydrogen Bond	Weak attraction between polar molecules	Between water molecules
Carbohydrate	Energy source	Glucose
Lipid	Energy storage, membrane structure	Triglyceride, phospholipid
Protein	Structure, enzymes, transport	Collagen, hemoglobin
Nucleic Acid	Genetic information	DNA, RNA
ATP	Cellular energy	Muscle contraction

Additional info:

• These notes cover foundational chemistry concepts essential for understanding cell components and processes in Anatomy & Physiology (relevant to chapters 2 and 3).

• Key terms and examples have been expanded for clarity and academic completeness.