LECTURE 1: Principal subdivisions of anatomy & physiology

Anatomy vs. Physiology

  • Anatomy: Study of body structure & parts.

    • Gross anatomy: Large, visible structures (regional, systemic, surface).

    • Microscopic anatomy: Cells (cytology) & tissues (histology).

    • Developmental anatomy: Structural changes from fertilization to maturity (embryology).

  • Physiology: Study of how body parts function.

Levels of Structural Organization

  1. Chemical (atoms → molecules)

  2. Cellular (cells)

  3. Tissue (groups of similar cells)

  4. Organ (different tissues working together)

  5. Organ system (organs working closely)

  6. Organism (all systems combined)

Body Systems Overview

  • Integumentary: External covering, protects, vitamin D synthesis, receptors.

  • Skeletal: Protection, support, blood cell formation, mineral storage.

  • Muscular: Movement, posture, heat production (skeletal, smooth, cardiac muscles).

  • Nervous: Fast control, responds to stimuli, activates muscles/glands.

  • Endocrine: Glands secrete hormones for growth, reproduction, metabolism.

  • Cardiovascular: Heart, blood vessels; transports O₂, CO₂, nutrients, wastes.

  • Lymphatic: Returns fluids, immunity, filters debris.

  • Respiratory: Gas exchange (O₂ in, CO₂ out).

  • Digestive: Breaks down food, absorbs nutrients, eliminates waste.

  • Urinary: Removes nitrogen waste, balances water/electrolytes, pH regulation.

  • Reproductive: Produces offspring, new cells for growth/repair.

Necessary Life Functions

  • Maintain boundaries (skin/membranes).

  • Movement (locomotion & substances).

  • Responsiveness (react to stimuli).

  • Digestion (breakdown & nutrient delivery).

  • Metabolism (catabolism = breakdown, anabolism = build-up).

  • Excretion (waste removal).

  • Reproduction (offspring & cell repair).

  • Growth (increase cell size/number).

Survival Needs

  • Nutrients: Carbs, proteins, lipids, vitamins, minerals.

  • Oxygen: Required for energy production.

  • Water: 60–80% body weight, metabolic role.

  • Stable temperature & appropriate pressure needed.

Homeostasis

  • Self-regulating balance of internal environment.

  • Controlled by feedback systems:

    • Receptor (detects change) → Control center (sets response) → Effector (acts).

    • Negative feedback: Reverses change (e.g., body temp).

    • Positive feedback: Enhances change (e.g., childbirth contractions).

  • Homeostatic imbalance leads to disease (e.g., diabetes, aging-related decline).