Study Notes: Human Body Orientation & Basic Chemistry for ANP

Chapter 1: The Human Body – An Orientation

Anatomical Position

The anatomical position is a standardized posture used to describe the locations and relationships of body parts. It serves as a reference point in anatomy.

• Definition: The body stands upright, facing forward, with feet parallel and flat on the floor, arms at the sides, and palms facing forward.

• Importance: Ensures clear and consistent communication about body parts and their locations.

• Example: The thumb is lateral to the little finger in anatomical position.

Homeostasis and Feedback Systems

Homeostasis is the maintenance of a stable internal environment in the body. It is primarily regulated by feedback systems.

• Negative Feedback: A process that reverses a change in a controlled condition, bringing the system back to its set point.

• Positive Feedback: A process that amplifies a change, moving the system further from its original state.

• Example (Negative Feedback): Regulation of body temperature—if body temperature rises, mechanisms such as sweating are activated to cool the body.

• Example (Positive Feedback): Blood clotting—platelets release chemicals to attract more platelets, accelerating clot formation.

Key Point: Negative feedback is more common and essential for maintaining homeostasis, while positive feedback usually occurs in specific situations.

Chapter 2: Chemistry Comes Alive

Atomic Structure

Atoms are the basic units of matter, composed of three main subatomic particles:

• Proton: Positively charged particle found in the nucleus.

• Neutron: Neutral particle (no charge) found in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

Chemical Elements

• Chemical Element: A pure substance consisting of only one type of atom, distinguished by its atomic number.

• Major Elements in the Body: Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N) – these four elements make up about 96% of body mass.

Chemical Bonds

• Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions (e.g., NaCl).

• Covalent Bonds: Formed when atoms share electrons.

  • Non-polar Covalent: Electrons are shared equally (e.g., O2).

  • Polar Covalent: Electrons are shared unequally, creating partial charges (e.g., H2O).

• Hydrogen Bonds: Weak attractions between a hydrogen atom (already covalently bonded to an electronegative atom) and another electronegative atom (e.g., between water molecules).

Organic vs. Inorganic Compounds

• Organic Compounds: Contain carbon and hydrogen, often large and complex (e.g., carbohydrates, proteins, lipids, nucleic acids).

• Inorganic Compounds: Generally do not contain carbon-hydrogen bonds (e.g., water, salts, acids, bases).

Hydrophilic vs. Hydrophobic Compounds

• Hydrophilic: "Water-loving"; substances that dissolve easily in water (e.g., salts, sugars).

• Hydrophobic: "Water-fearing"; substances that do not dissolve in water (e.g., oils, fats).

Carbohydrates

• Building Blocks: Monosaccharides (simple sugars, e.g., glucose).

• General Structure: Composed of carbon, hydrogen, and oxygen (C:H:O ratio is 1:2:1).

• Biological Functions: Main source of energy for cells; structural roles in some organisms.

• Example: Starch (plants), glycogen (animals).

Lipids

• Building Blocks: Glycerol and fatty acids.

• General Structure: Mostly nonpolar molecules; include triglycerides, phospholipids, and steroids.

• Biological Functions: Energy storage, insulation, protection, and cell membrane structure.

• Example: Triglycerides (fats and oils), cholesterol.

Proteins

• Building Blocks: Amino acids (20 types).

• General Structure: Chains of amino acids linked by peptide bonds; folded into specific shapes.

• Biological Functions: Enzymes, structural support, transport, movement, defense.

• Example: Hemoglobin, collagen.

Levels of Protein Structure

• Primary: Sequence of amino acids.

• Secondary: Local folding (alpha-helix, beta-sheet).

• Tertiary: Overall 3D shape of a single polypeptide.

• Quaternary: Arrangement of multiple polypeptide chains.

• Denaturation: Loss of protein structure (and function) due to heat, pH changes, or chemicals.

• Impact: Denatured proteins cannot perform their biological functions.

DNA vs. RNA

• DNA (Deoxyribonucleic Acid): Double-stranded, contains deoxyribose sugar, bases are A, T, C, G; stores genetic information.

• RNA (Ribonucleic Acid): Single-stranded, contains ribose sugar, bases are A, U, C, G; involved in protein synthesis.

ATP and Cell Metabolism

• ATP (Adenosine Triphosphate): The main energy currency of the cell.

• Role: Stores and releases energy for cellular processes.

• Equation:

$ \mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i} + \text{energy} $

• Example: Muscle contraction, active transport across membranes.