Chemistry Foundations for Anatomy & Physiology

• Chemistry Foundations for Anatomy & Physiology

Atoms and Molecules

Understanding the basic units of matter is essential for studying Anatomy & Physiology, as all biological processes are rooted in chemical interactions.

• Atom: The smallest unit of matter that retains the properties of an element.

• Subatomic particles:

  • Electrons (e): Negatively charged particles found in electron shells around the nucleus.

  • Protons (p): Positively charged particles located in the nucleus.

  • Neutrons (n): Neutral particles also found in the nucleus.

• Molecule: Two or more atoms chemically bonded together (e.g., H2O, C6H12O6, O2, N2).

Ions and Common Elements in Anatomy & Physiology

Ions and elements are fundamental to physiological processes such as nerve conduction, muscle contraction, and fluid balance.

• Ion: An atom or molecule with a net electric charge due to the loss or gain of electrons.

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

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

• Common elements in A&P: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Calcium (Ca), Phosphorus (P), Potassium (K), Magnesium (Mg), Sodium (Na).

Chemical Bonds

Chemical bonds are the forces that hold atoms together in molecules and compounds, crucial for the structure and function of biological molecules.

• Valence shell: The outermost electron shell of an atom, involved in bonding.

• Three major types of chemical bonds:

  • Ionic bonds

  • Covalent bonds

  • Hydrogen bonds

Chemical Bonds: Ionic

Ionic bonds form between atoms that transfer electrons, resulting in oppositely charged ions that attract each other.

• Ionic bond: Formed when one atom donates an electron (becoming a cation) and another atom accepts it (becoming an anion).

• Example: Sodium (Na) loses an electron to become Na+; Chlorine (Cl) gains an electron to become Cl-. They form NaCl (table salt).

• Properties:

  • Compounds formed are called salts.

  • Salts dissociate in water, releasing ions.

Chemical Bonds: Covalent

Covalent bonds involve the sharing of electron pairs between atoms, creating strong and stable molecules essential for life.

• Covalent bond: Atoms share one or more pairs of electrons.

• Single bond: One pair of electrons is shared (e.g., H2).

• Double bond: Two pairs of electrons are shared (e.g., O2).

• Polar covalent bond: Electrons are shared unequally, resulting in partial charges (e.g., H2O).

• Nonpolar covalent bond: Electrons are shared equally (e.g., O2).

Table: Comparison of Bond Types

Bond Type	How Formed	Example	Relative Strength
Ionic	Transfer of electrons	NaCl	Moderate (weaker in water)
Covalent	Sharing of electrons	H2O, O2	Strong
Hydrogen	Attraction between partial charges	Between H2O molecules	Weak (individually)

Additional info: Hydrogen bonds, though weak individually, are critical for the structure of DNA and proteins.