Fundamental Chemistry Concepts for Anatomy & Physiology

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Atom: The smallest unit of matter that retains the properties of an element. Atoms consist of protons, neutrons, and electrons.
Element: A pure substance made of only one kind of atom, defined by its number of protons (atomic number).
Isotope: Atoms of the same element with different numbers of neutrons, resulting in different mass numbers. Some isotopes are stable, while others are radioactive.
Example: Carbon-12 and Carbon-14 are isotopes of carbon.

Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions (cations and anions) that attract each other.
Covalent Bonds: Formed when two atoms share one or more pairs of electrons.
Hydrogen Bonds: Weak attractions between a hydrogen atom (already covalently bonded to an electronegative atom) and another electronegative atom.
Example: Sodium chloride (NaCl) forms via ionic bonding; water (H2O) molecules are held together by covalent bonds and interact via hydrogen bonds.

Synthesis Reactions: Two or more substances combine to form a more complex product.
Decomposition Reactions: A complex molecule breaks down into simpler substances.
Exchange Reactions: Parts of molecules are exchanged to form new compounds.
Example: The breakdown of glucose during cellular respiration is a decomposition reaction.

Enzyme: A protein that speeds up chemical reactions in the body without being consumed in the process.
Active Site: The region on the enzyme where the substrate binds and the reaction occurs.
Specificity: Each enzyme acts on a specific substrate due to the shape of its active site.
Example: Amylase breaks down starch into sugars in the mouth.

Inorganic Compounds: Generally do not contain carbon-hydrogen (C-H) bonds. Examples include water, salts, acids, and bases.
Organic Compounds: Contain carbon and usually hydrogen; often large and complex. Examples include carbohydrates, lipids, proteins, and nucleic acids.
Example: Glucose (C6H12O6) is organic; sodium chloride (NaCl) is inorganic.

Water: The most abundant compound in the body; excellent solvent, involved in temperature regulation and chemical reactions.
pH: A measure of hydrogen ion concentration; scale ranges from 0 (acidic) to 14 (basic), with 7 being neutral.
Acid-Base Balance: The body maintains a narrow pH range (7.35–7.45 in blood) for proper physiological function.
Salts: Ionic compounds that dissociate in water to form electrolytes, essential for nerve and muscle function.
Example: Sodium bicarbonate (NaHCO3) acts as a buffer in blood.

Functional Group: A specific group of atoms within a molecule that determines its chemical properties and reactions.
Common Functional Groups:
- Hydroxyl (-OH): Found in alcohols and carbohydrates.
- Carboxyl (-COOH): Found in amino acids and fatty acids.
- Amino (-NH2): Found in amino acids.
- Phosphate (-PO42-): Found in nucleic acids and ATP.
Example: The carboxyl group gives amino acids their acidic properties.

Carbohydrates: Provide energy and structural support. Monomers are monosaccharides (e.g., glucose).
Lipids: Store energy, form cell membranes, and act as signaling molecules. Include fats, oils, and steroids.
Proteins: Perform a wide range of functions, including catalysis (enzymes), structure, transport, and defense. Made of amino acids.
Nucleic Acids: Store and transmit genetic information. DNA and RNA are polymers of nucleotides.
Example: Hemoglobin (protein), starch (carbohydrate), triglyceride (lipid), DNA (nucleic acid).

ATP (Adenosine Triphosphate): The primary energy carrier in cells. Energy is released when ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate.
ATP Hydrolysis Equation:
Role in Physiology: ATP powers cellular processes such as muscle contraction, active transport, and biosynthesis.
Example: Muscle cells use ATP to contract during movement.