Chapter 1 Part A: The Human Body - An Orientation

Anatomy & Physiology

  • Anatomy: Study of body structure and relationships.
  • Physiology: Study of body part functions and life-sustaining activities.

Topics of Anatomy

  • Gross Anatomy:
    • Regional: Structures in a specific body area.
    • System: One system (e.g., cardiovascular).
    • Surface: Internal structures related to overlying skin.
  • Microscopic Anatomy:
    • Cytology: Study of cells.
    • Histology: Study of tissues.
  • Developmental Anatomy:
    • Embryology: Study of developments before birth.

Topics of Physiology

  • Focuses on organ systems and cellular/molecular levels.
  • Dependent on chemical reactions in cells.
  • Requires understanding of physical and chemical principles.

Complementarity of Structure and Function

  • Function reflects structure.
  • What a structure can do depends on its form.

Structural Organization

  • Chemical level: atoms, molecules, and organelles
  • Cellular level: single cell
  • Tissue level: groups of similar cells
  • Organ level: contains two or more types of tissues
  • Organ system level: organs that work closely together
  • Organismal level: all organ systems combined to make the whole organism

Necessary Life Functions

  • Maintaining boundaries: separation between internal and external environments
  • Movement: body parts or substances
  • Responsiveness: Ability to sense and respond to stimuli
  • Digestion: Breakdown of ingested foodstuffs
  • Metabolism: All chemical reactions in body cells
    • Catabolism: Breakdown of molecules
    • Anabolism: Synthesis of molecules
  • Excretion: Removal of wastes
  • Reproduction: At the cellular or organismal level
  • Growth: Increase in size

Survival Needs

  • Nutrients: Chemicals for energy and cell building
    • Carbohydrates: energy source
    • Proteins: needed for cell building and cell chemistry
    • Fats: long-term energy storage
    • Minerals and vitamins: involved in chemical reactions as well as for structural purposes
  • Oxygen: Essential for energy release.
  • Water: For chemical reactions, secretions, and excretions.
  • Normal body temperature: Affects chemical reaction rates. Normal body temperature is 37°C.
  • Appropriate atmospheric pressure: Needed for breathing and gas exchange.

Homeostasis

  • Maintenance of stable internal conditions.
  • Dynamic equilibrium maintained by organ systems.

Homeostatic Controls

  • Variables: Factors that can change (e.g., blood sugar).
  • Components:
    • Receptor: Monitors environment, responds to stimuli.
    • Control center: Determines set point, receives input, determines response.
    • Effector: Provides means to respond, reduces or enhances stimulus.

Feedback Mechanisms

  • Negative Feedback: Reduces or shuts off original stimulus.
    • Regulation of body temperature and blood glucose.
  • Positive Feedback: Enhances original stimulus.
    • Examples: Labor contractions, blood clotting.

Homeostatic Imbalance

  • Increases risk of disease and aging.
  • Destructive positive feedback mechanisms may take over.