Study Guide: The Human Body Orientation & Chemistry Comes Alive (BI-013 Exam 2)

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CH 01. The Human Body: An Orientation

Anatomical Position

The anatomical position is a standardized posture used to describe locations and directions on the human body. It serves as a reference point for anatomical terminology.

Definition: The body stands upright, facing forward, feet together, arms at the sides, and palms facing forward.
Importance: Provides consistency in anatomical descriptions and avoids confusion.
Example: The thumb is lateral to the little finger in anatomical position.

Feedback Systems and Homeostasis

Feedback systems are mechanisms that help maintain homeostasis, the body's stable internal environment.

Negative Feedback: A process that reverses a change, bringing the system back to its set point. Most homeostatic mechanisms are negative feedback.
Example: Regulation of blood glucose levels by insulin.
Positive Feedback: A process that amplifies a change, moving the system further from its set point. Used in specific situations.
Example: Blood clotting and labor contractions.

Additional info: Negative feedback is essential for maintaining stability, while positive feedback is typically used for rapid, self-amplifying events.

CH 02. Chemistry Comes Alive

Components of the Atom

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

Proton: Positively charged particle found in the nucleus.
Neutron: Neutral particle found in the nucleus.
Electron: Negatively charged particle orbiting the nucleus.

Additional info: The number of protons determines the atomic number and identity of the element.

Chemical Elements

A chemical element is a substance that cannot be broken down into simpler substances by ordinary chemical means.

Four Major Elements in the Body: Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N).
Importance: These elements make up over 96% of body mass.

Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules.

Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions.
Covalent Bonds: Formed when atoms share electrons.
Non-polar Covalent: Electrons are shared equally.
Polar Covalent: Electrons are shared unequally, creating partial charges.
Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

Example: Water molecules are held together by hydrogen bonds.

Organic vs Inorganic Compounds

Compounds in the body are classified as organic or inorganic.

Organic Compounds: Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids.
Inorganic Compounds: Do not contain carbon; include water, salts, acids, and bases.

Additional info: Organic compounds are typically larger and more complex than inorganic compounds.

Hydrophilic vs Hydrophobic Compounds

Compounds are classified based on their affinity for water.

Hydrophilic: "Water-loving"; dissolve easily in water (e.g., salts, sugars).
Hydrophobic: "Water-fearing"; do not dissolve in water (e.g., oils, fats).

Carbohydrates

Carbohydrates are organic molecules that serve as the body's main energy source.

Building Blocks: Monosaccharides (simple sugars, e.g., glucose).
General Structure: Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
Biological Functions: Provide energy, store energy (glycogen), and serve as structural components (cellulose in plants).

Example: Glucose is used in cellular respiration to produce ATP.

Lipids

Lipids are hydrophobic organic molecules important for energy storage and cell structure.

Building Blocks: Glycerol and fatty acids.
General Structure: Mostly nonpolar hydrocarbons; include triglycerides, phospholipids, and steroids.
Biological Functions: Energy storage, insulation, protection, and forming cell membranes.

Example: Phospholipids form the bilayer of cell membranes.

Proteins

Proteins are complex organic molecules essential for structure and function in the body.

Building Blocks: Amino acids.
General Structure: Chains of amino acids linked by peptide bonds.
Biological Functions: Enzymes, structural support, transport, signaling, and immune defense.

Example: Hemoglobin transports oxygen in blood.

Levels of Protein Structure & Denaturation

Proteins have four structural levels:

Primary: Sequence of amino acids.
Secondary: Local folding (alpha helix, beta sheet).
Tertiary: Overall 3D shape.
Quaternary: Association of multiple polypeptide chains.
Denaturation: Loss of protein structure due to heat, pH, or chemicals, resulting in loss of function.

Example: Cooking an egg denatures its proteins.

Additional info: Denaturation is often irreversible and disrupts biological activity.

DNA vs RNA

DNA and RNA are nucleic acids that store and transmit genetic information.

DNA: Double-stranded, contains deoxyribose, bases are A, T, C, G; stores genetic information.
RNA: Single-stranded, contains ribose, bases are A, U, C, G; involved in protein synthesis.

Additional info: DNA is found in the nucleus; RNA is found in the cytoplasm.

ATP and Cell Metabolism

ATP (Adenosine Triphosphate) is the primary energy carrier in cells.

Role: Provides energy for cellular processes such as muscle contraction, active transport, and biosynthesis.
Structure: Composed of adenine, ribose, and three phosphate groups.
Equation:

Example: ATP is used to power the sodium-potassium pump in cell membranes.