Anatomy & Physiology: Core Concepts and Study Guide

1. Levels of Organization & Organ Systems

Levels of Organization

The human body is organized in a hierarchical structure, from the simplest to the most complex:

• Subatomic particles

• Atoms

• Molecules

• Organelles

• Cells

• Tissues

• Organs

• Organ systems

• Organism (the human body)

Example: Muscle cell (cell) → Muscle tissue → Heart (organ) → Cardiovascular system (organ system) → Human body (organism).

Key Terms:

• Anatomy: The study of body structure.

• Physiology: The study of body function.

Organ Systems

The human body contains 11 major organ systems, each with specific functions. Examples include:

• Cardiovascular system: Transports blood, nutrients, gases, and wastes.

• Respiratory system: Facilitates gas exchange (oxygen and carbon dioxide).

Application: Each organ system works together to maintain homeostasis and overall health.

2. Major Themes in Physiology

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite external changes. It is essential for normal body function.

• Dynamic equilibrium: The body constantly adjusts to maintain balance.

• Static equilibrium: No change occurs (rare in living systems).

Feedback Mechanisms:

• Negative feedback: Reverses a change to maintain homeostasis (e.g., body temperature regulation).

• Positive feedback: Amplifies a change (e.g., blood clotting).

Example: When body temperature rises, mechanisms such as sweating are activated to cool the body (negative feedback).

3. Elements, Atomic Structure, Ion Formation & Isotopes

Elements & Atoms

• Element: A pure substance consisting of one type of atom, defined by its atomic number (number of protons).

• Atom: The smallest unit of an element, composed of protons, neutrons, and electrons.

Subatomic Particles:

• Protons: Positive charge, in nucleus

• Neutrons: No charge, in nucleus

• Electrons: Negative charge, orbit nucleus

Valence electrons determine chemical reactivity.

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons.

• Example: Hydrogen, deuterium, and tritium are isotopes of hydrogen.

Ions & Ion Formation

• Cation: Positively charged ion (loss of electron).

• Anion: Negatively charged ion (gain of electron).

Example: Sodium (Na) loses an electron to become Na+ (cation); Chlorine (Cl) gains an electron to become Cl- (anion).

4. Types of Bonding and Compounds

Octet Rule

Atoms tend to gain, lose, or share electrons to achieve a full outer shell (usually 8 electrons).

Ionic Bonding

• Involves transfer of electrons from one atom to another, forming ions.

• Example: NaCl (sodium chloride).

Covalent Bonding

• Involves sharing of electron pairs between atoms.

• Single, double, and triple bonds refer to the number of shared electron pairs.

• Example: H2O (water), CO2 (carbon dioxide).

5. Water, Solutions, and pH

Properties of Water

• Polarity: Water is a polar molecule with partial positive (H) and negative (O) charges.

• Hydrogen bonding: Attraction between water molecules.

• High heat capacity and surface tension are important for body temperature regulation.

Solutions, Colloids, and Suspensions

• Solution: Homogeneous mixture (e.g., salt water).

• Colloid: Particles do not settle (e.g., cytoplasm).

• Suspension: Particles settle over time (e.g., blood cells in plasma).

pH, Acids & Bases

• pH: Measures hydrogen ion concentration; scale from 0 (acidic) to 14 (basic), 7 is neutral.

• Acid: Releases H+ ions in solution.

• Base: Accepts H+ ions or releases OH-.

Formula:

$pH = -\log_{10}[H^+]$

Example: Blood pH is tightly regulated around 7.4.

6. Metabolism & Chemical Reactions

Types of Reactions

• Anabolic reactions: Build complex molecules (require energy).

• Catabolic reactions: Break down molecules (release energy).

Example: Protein synthesis (anabolic); cellular respiration (catabolic).

Catalysts & Enzymes

• Catalyst: Substance that speeds up a chemical reaction without being consumed.

• Enzyme: Biological catalyst, usually a protein.

• Active site: Region on enzyme where substrate binds.

Enzyme activity can be affected by temperature, pH, and substrate concentration.

7. Organic Chemistry: Molecules of Life

Organic Compounds

Organic molecules contain carbon and form the backbone of living matter.

• Functional groups: Specific groupings of atoms that confer properties (e.g., hydroxyl, carboxyl, amino, phosphate).

8. Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose, C6H12O6).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains (e.g., glycogen, starch).

Example: Glucose is a primary energy source for cells.

9. Proteins

• Amino acids: Building blocks of proteins; 20 standard types.

• Peptide bonds: Link amino acids.

• Protein structure: Primary (sequence), secondary (folding), tertiary (3D shape), quaternary (multiple chains).

Denaturation: Loss of protein structure and function due to heat or pH changes.

10. Nucleic Acids

• DNA: Stores genetic information; double helix structure.

• RNA: Involved in protein synthesis; single-stranded.

• Nucleotide: Building block (sugar, phosphate, nitrogenous base).

ATP: Main energy currency of the cell.

11. Lipids

• Triglycerides: Main form of stored energy; composed of glycerol and three fatty acids.

• Phospholipids: Major component of cell membranes.

• Steroids: Include cholesterol and hormones.

Saturated vs. Unsaturated Fats: Saturated fats have no double bonds; unsaturated fats have one or more double bonds.

12. Cell Structure & Organelle Functions

Major Organelles

• Nucleus: Contains DNA, controls cell activities.

• Ribosomes: Protein synthesis.

• Endoplasmic reticulum (ER): Rough ER (protein synthesis), Smooth ER (lipid synthesis).

• Golgi apparatus: Modifies and packages proteins.

• Lysosomes: Digestive enzymes.

• Mitochondria: ATP production.

• Cytoskeleton: Structural support (microfilaments, intermediate filaments, microtubules).

13. Cell Membrane Structure & Permeability

• Phospholipid bilayer: Main component, with embedded proteins.

• Fluid mosaic model: Describes membrane structure as flexible and dynamic.

• Junctions: Tight junctions, desmosomes, gap junctions.

14. Membrane Transport

Passive Transport

• Simple diffusion: Movement of molecules from high to low concentration.

• Facilitated diffusion: Uses carrier or channel proteins.

• Osmosis: Diffusion of water across a membrane.

Active Transport

• Requires energy (ATP) to move substances against concentration gradient.

• Primary active transport: Direct use of ATP (e.g., Na+/K+ pump).

• Secondary active transport: Uses energy from another gradient.

• Bulk transport: Endocytosis (into cell), exocytosis (out of cell).

15. Summary Table: Types of Membrane Transport

Type	Energy Required?	Direction	Example
Simple Diffusion	No	High to Low	O2 across membrane
Facilitated Diffusion	No	High to Low	Glucose via carrier protein
Osmosis	No	High to Low (water)	Water across membrane
Active Transport	Yes (ATP)	Low to High	Na+/K+ pump
Bulk Transport	Yes (ATP)	Varies	Endocytosis, exocytosis

16. Additional info:

• Some content was inferred and expanded for clarity and completeness, such as the summary table and detailed explanations of feedback mechanisms, membrane transport, and organic molecules.

• For full details, refer to the indicated textbook chapters and sections.