Fundamental Chemistry Concepts for Anatomy & Physiology

Matter and Energy

States of Matter

Understanding the basic states of matter is essential for studying the human body, as all biological processes involve chemical substances in various forms.

• Solid, Liquid, Gas: The three primary states of matter. Biological systems primarily involve liquids (e.g., blood, cytosol) and solids (e.g., bone).

Energy

Energy is the capacity to do work and is fundamental to all physiological processes.

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy, such as chemical energy in bonds.

• Types of Energy: Chemical, mechanical, electrical (movement of charge), and electromagnetic.

• Energy Conversion: Energy can be converted from one form to another, but some is lost as heat (inefficient conversion).

Atoms and Elements

Atomic Structure

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

• Subatomic Particles: Protons (positive), neutrons (neutral), electrons (negative).

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

• Isotopes: Atoms with the same number of protons but different numbers of neutrons; some are radioactive.

• Planetary Model: Electrons orbit the nucleus in probable regions called orbitals.

• Electron Shells: Electrons are arranged in shells; the outermost shell is the valence shell.

• Octet Rule: Atoms are most stable with 8 electrons in their outer shell (except for the first shell, which is full with 2 electrons).

• Valence Electrons: Electrons in the outermost shell, important for chemical reactivity.

Elements in the Human Body

• Major Elements: Oxygen, carbon, hydrogen are most abundant.

Chemical Bonds

Ionic Bonds

Ionic bonds form when electrons are transferred from one atom to another, resulting in charged ions.

• Ion: An atom or molecule with a net electric charge.

• Cation: Positively charged ion (e.g., Na+).

• Anion: Negatively charged ion (e.g., Cl-).

• Example: Sodium (Na) loses one electron to become Na+; chlorine (Cl) gains one electron to become Cl-.

Covalent Bonds

Covalent bonds form when atoms share electrons. These can be polar or nonpolar depending on the electronegativity of the atoms involved.

• Polar Covalent: Unequal sharing of electrons (e.g., water, H2O).

• Nonpolar Covalent: Equal sharing of electrons (e.g., O2).

• Electronegativity: The tendency of an atom to attract electrons; higher electronegativity means stronger pull.

Hydrogen Bonds

Hydrogen bonds are weak attractions between polar molecules, important in water and biological macromolecules.

• Found in: Water molecules, DNA, proteins.

• Role: Stabilize structures and allow for dynamic interactions.

Chemical Reactions

Types of Chemical Reactions

Chemical reactions involve the making or breaking of bonds, transforming substances.

• Anabolic Reactions: Synthesis of complex molecules (e.g., protein synthesis).

• Catabolic Reactions: Breakdown of molecules (e.g., digestion of glycogen).

• Metabolism: The sum of all anabolic and catabolic reactions in the body.

• Decomposition: Breaking down compounds into simpler ones.

Energy in Chemical Reactions

• Exergonic: Release energy; products have less potential energy than reactants.

• Endergonic: Absorb energy; products have more potential energy than reactants.

Rate of Chemical Reactions

The rate at which chemical reactions occur is influenced by several factors:

• Temperature: Higher temperature increases kinetic energy and reaction rate.

• Concentration: Higher concentration increases reaction rate.

• Particle Size: Smaller particles react faster.

• Catalysts: Substances (e.g., enzymes) that increase reaction rate without being consumed.

Solutions and Mixtures

Types of Mixtures

Mixtures are combinations of substances that are not chemically bonded.

• Solution: Homogeneous mixture (e.g., water).

• Colloid: Intermediate mixture (e.g., gelatin, cytosol).

• Suspension: Heterogeneous mixture (e.g., blood).

Salts, Acids, Bases, and Buffers

Salts

Salts are ionic compounds that dissociate in water to form electrolytes, which conduct electrical currents.

• Role: Important for maintaining electrical balance and physiological functions.

Acids and Bases

Acids and bases are substances that affect the pH of solutions.

• pH Scale: Measures acidity/alkalinity (0-14).

• Acid: Proton donor; increases hydrogen ion concentration.

• Base: Proton acceptor; decreases hydrogen ion concentration.

• Neutralization: Mixing acids and bases results in a displacement reaction, forming water and a salt.

Important Acids and Bases

• Acids: HCl, H2CO3

• Bases: HCO3- (bicarbonate), NH4

Buffers

Buffers help maintain stable pH in biological systems by releasing or binding hydrogen ions.

• Bicarbonate Buffer System: Major buffer in blood.

• Function: Prevents abrupt changes in pH.

Carbohydrates

Classification of Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They are a primary energy source for the body.

• Monosaccharides: Single sugar units (3-7 carbon atoms); e.g., glucose.

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

• Polysaccharides: Many monosaccharides linked together; e.g., glycogen.

Type	Number of Sugar Units	Example
Monosaccharide	1	Glucose
Disaccharide	2	Sucrose
Polysaccharide	Many	Glycogen

• Pentose: 5-carbon sugar.

• Hexose: 6-carbon sugar.

• -ose: Suffix indicating a sugar.

Additional info: Carbohydrates are vital for energy storage and supply, cell structure, and signaling in the human body.