Basic Chemistry Concepts for Anatomy & Physiology

Basic Chemistry for Anatomy & Physiology

Structure of an Atom

Atoms are the fundamental units of matter, forming all living and non-living things. Understanding atomic structure is essential for grasping chemical processes in the body.

• Subatomic Particles:

  • Protons: Positively charged particles found in the nucleus.

  • Neutrons: Neutral particles also located in the nucleus.

  • Electrons: Negatively charged particles orbiting the nucleus.

• Atomic Neutrality: Atoms are electrically neutral when the number of protons equals the number of electrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

Ions

Ions are atoms or molecules that have gained or lost electrons, resulting in a net electrical charge. They play crucial roles in physiological processes.

• If an atom gains electrons, it becomes a negative ion (anion).

• If an atom loses electrons, it becomes a positive ion (cation).

• Electrolytes: Important ions in the body that conduct electricity in solution.

  • Calcium: Ca2+

  • Sodium: Na+

  • Potassium: K+

  • Hydrogen: H+

  • Chloride: Cl-

• Example: Table salt (NaCl) dissolves in water to form Na+ and Cl- ions.

Chemical Bonds

Chemical bonds hold atoms together to form molecules, which are essential for biological structure and function.

• Ionic Bonds: Formed by the transfer of electrons from one atom to another.

  • Example: NaCl (sodium chloride)

• Covalent Bonds: Formed by sharing electrons between atoms.

  • Example: O2 (oxygen gas)

• Organic vs. Inorganic Compounds:

  • Organic: Contain covalently bonded carbon atoms (e.g., carbohydrates, proteins, lipids, nucleic acids).

  • Inorganic: Usually lack carbon; include water, salts, acids, bases.

  • Some inorganic compounds contain carbon, such as:

    • H2CO3 (Carbonic Acid)

    • HCO3- (Bicarbonate)

    • CO2 (Carbon Dioxide)

    • CO (Carbon Monoxide)

Water (Inorganic)

Water is the most abundant substance in cells and is vital for life. Its unique properties make it essential for physiological processes.

• Composed of 2 hydrogen atoms and 1 oxygen atom (H2O).

• Polar molecule: Unequal sharing of electrons creates a slight charge difference.

• Universal solvent: Dissolves many substances, facilitating chemical reactions.

• Transports chemicals (e.g., nutrients).

• Maintains body temperature (high heat capacity).

Acids and Bases

Acids and bases are important for maintaining pH balance in the body, which is crucial for cellular function.

• Acids: Dissociate in water to release H+ ions.

  • Example: Hydrochloric acid (HCl) dissociates to H+ and Cl-.

• Bases: Dissociate in water to release OH- ions or accept H+ ions.

• pH Scale: Measures the concentration of H+ ions in solution.

  • Acidic: pH < 7

  • Neutral: pH = 7

  • Basic/Alkaline: pH > 7

  • Blood pH: 7.35 – 7.45

• Neutralization: $\text{H}^+ + \text{OH}^- \rightarrow \text{H}_2\text{O}$

Important Organic Substances

Organic molecules are the building blocks of life, including carbohydrates, lipids, proteins, and nucleic acids.

1) Carbohydrates

• Consist of carbon (C), hydrogen (H), and oxygen (O).

• General formula: (CH2O)n

• Functions:

  • Source of energy (e.g., glucose).

  • Structural components (e.g., DNA, RNA).

• Types:

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

  • Disaccharides: Two monosaccharides covalently bonded (e.g., sucrose = glucose + fructose).

  • Polysaccharides: Many monosaccharides bonded together (e.g., glycogen in animals, starch in plants).

2) Lipids

• Consist mainly of fatty acids and glycerol.

• Types:

  • Triglycerides: Glycerol + 3 fatty acids.

  • Phospholipids: Glycerol backbone, 2 fatty acids (non-polar), phosphate head group (polar).

  • Steroids: Derived from cholesterol, used to synthesize hormones.

• Functions:

  • Energy storage.

  • Insulation and padding.

  • Component of cell membranes.

3) Proteins

• Composed of amino acids (C, H, O, N, sometimes S).

• Functions:

  • Structural materials (e.g., collagen).

  • Enzymes, hormones, transporters.

  • Antibodies.

  • Energy source (when carbs & lipids are low).

• Naming:

  • Amino acids: Basic building blocks.

  • Dipeptides: Two amino acids joined.

  • Polypeptides: Many amino acids joined.

  • Protein: One or more polypeptides folded into final shape.

4) Nucleic Acids

• Composed of C, H, O, N, P.

• Types:

  • DNA: Double-stranded, contains deoxyribose sugar.

    • Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

    • Base pairing: A-T, C-G.

    • Function: Cellular reproduction, template for RNA.

  • RNA: Single-stranded, contains ribose sugar.

    • Bases: Adenine (A), Uracil (U), Cytosine (C), Guanine (G).

    • Function: Protein synthesis.

5) Adenosine Triphosphate (ATP)

• Modified RNA nucleotide; stores energy in covalent bonds.

• Structure: Adenine + ribose + 3 phosphate groups.

• Function: Powers cellular activities.

• Energy Release:

  • Breaking the bond between the 2nd and 3rd phosphate releases energy.

  • Equation: $\text{ATP} \rightarrow \text{ADP} + \text{P}_i$ (inorganic phosphate)

Type of Organic Molecule	Building Blocks	Main Functions	Examples
Carbohydrates	Monosaccharides	Energy, structure	Glucose, starch, glycogen
Lipids	Fatty acids, glycerol	Energy storage, membranes	Triglycerides, phospholipids, cholesterol
Proteins	Amino acids	Structure, enzymes, transport	Collagen, hemoglobin
Nucleic Acids	Nucleotides	Genetic information, protein synthesis	DNA, RNA, ATP

Additional info: These foundational chemistry concepts are essential for understanding physiological processes such as metabolism, cellular communication, and homeostasis in Anatomy & Physiology.