Introduction to Human Biology

Introduction to Human Biology

• Course Info: Using Open Education Resources (OER) from OpenStax.
• Resource License: © Rice University under CC-BY 4.0; can be modified with attribution.
• Content: Mix of OpenStax and original explanations by Dr. Ahmed Katsha.

Chapter 1: The Human Body - An Orientation

• Learning Objectives:
  • Differentiate between anatomy and physiology.
  • Describe body structure in six levels of organization.
  • Identify functional characteristics of human life and requirements for survival.
  • Define homeostasis and its importance.
  • Use anatomical terminology to label body structures.

Anatomy vs. Physiology

• Anatomy: Study of body structures and their relationships.
• Physiology: Study of chemistry and physics of body structures and their functions.
• Both disciplines complement each other in understanding the body.

Principle of Complementarity

• Understanding anatomical design requires knowledge of physiology.
  • Example: Heart's anatomical position supports its function in blood circulation.

Levels of Structural Organization

• Hierarchy: Atoms → Molecules → Organelles → Cells → Tissues → Organs → Organ Systems → Organism

Organ Systems Overview

1. Integumentary System: Protects internal structures and sensory receptors.
2. Skeletal System: Supports body and enables movement.
3. Muscular System: Facilitates movement and body temperature regulation.
4. Nervous System: Processes sensory information and activates responses.
5. Endocrine System: Secretes hormones and regulates bodily processes.
6. Cardiovascular System: Transports nutrients and oxygen.
7. Lymphatic System: Returns fluid to blood and protects against pathogens.
8. Respiratory System: Facilitates gas exchange.
9. Digestive System: Processes food and eliminates waste.
10. Urinary System: Manages water balance and waste excretion.
11. Reproductive Systems: Produce hormones and gametes; support embryo development.

Functional Requirements of Life

• Vital for maintaining life:
  • Organization: Cells organized to maintain internal compartments.
  • Metabolism: Sum of all chemical processes (anabolism + catabolism).
  • Responsiveness: Ability to react to environmental changes.
  • Movement: Includes internal and external motions.
  • Development & Growth: Changes and size increases throughout life.
  • Reproduction: Formation of new organisms to ensure species continuity.

Homeostasis

• Definition: The body's dynamic balance around a set point essential for functioning.

• Examples of Variables: Body temperature, blood pressure, hydration

• Homeostasis Involves:

  • All organ systems, especially nervous and endocrine.
  • Continuous adjustment as conditions change.

• Homeostatic Regulation Components:

  • Receptors: Sensors of physiological values that initiate responses.
  • Control Center: Decides the response needed to maintain set points.
  • Effectors: Act on signals from the control center to restore balance.

Feedback Mechanisms

• Negative Feedback:

  • Reverses deviations from normal range.
  • Examples: Temperature regulation, blood glucose management.

• Positive Feedback:

  • Intensifies changes until a specific goal is achieved.
  • Examples: Blood clotting, childbirth.

Homeostatic Imbalance

• Disruption can lead to diseases (e.g., diabetes, hypertension).
• Aging reduces the body's ability to maintain homeostasis.

Anatomical Position and Directional Terms

• Standard Anatomical Position: Upright, feet parallel, palms facing forward.

• Directional Terms:

  • Anterior/Ventral: Front (e.g., toes are anterior to the foot).
  • Posterior/Dorsal: Back (e.g., knee is posterior to the thigh).
  • Superior/Cranial: Above (e.g., head is superior to chest).
  • Inferior/Caudal: Below (e.g., abdomen is inferior to chest).
  • Medial: Towards midline (e.g., heart is medial to lungs).
  • Lateral: Away from midline (e.g., ears are lateral to nose).
  • Proximal: Nearer to trunk (e.g., elbow is proximal to wrist).
  • Distal: Farther from trunk (e.g., fingers are distal to elbow).
  • Superficial: Closer to surface (e.g., skin is superficial to bones).
  • Deep: Farther from surface (e.g., lungs are deep to rib cage).

Body Cavities and Serous Membranes

• Ventral Cavity: Houses soft organs; divided into thoracic and abdominopelvic cavities.
• Dorsal Cavity: Protects nervous system; includes cranial and vertebral cavities.
• Serous Membrane: Thin membranes covering organs; consist of parietal and visceral layers, reduce friction.

Abdominopelvic Regions and Quadrants

• Quadrants:
  • Left Upper (LUQ), Right Upper (RUQ), Left Lower (LLQ), Right Lower (RLQ)
• Regions:
  • Right hypochondriac, Epigastric, Left hypochondriac, Right lumbar, Umbilical, Left lumbar, Right iliac, Hypogastric, Left iliac.