Introduction to Human Physiology

Overview

• Physiology is derived from Greek words:
  • Physis: Origin or nature
  • Logia: The study of
• Focus on Human Physiology: Study of function and mechanisms of the human body.

Key Definitions

• Physiology: Study of function and mechanisms in the body.
  • In contrast to Anatomy, which is the study of structure.
• Regulation and Communication:
  • Fast communication via neurons.
  • Slow communication via the endocrine system.

Cellular Basics

• Cell: Basic living unit of the body.
• Approximately 100 trillion cells in the human body.

Internal Environment (Milieu Intérieur)

• 60% of body weight is water:
  • Intracellular Fluid (ICF): Inside cells, 2/3 of total body water (~40 liters).
  • Extracellular Fluid (ECF): Outside cells, 1/3 of total body water (~20 liters).
• ECF surrounds cells: Called the "internal environment."

Composition of ECF

• Components:
  • Good stuff:
    • Ions: Sodium, Chloride, Bicarbonate
    • Nutrients: Amino acids, fatty acids, glucose
  • Bad stuff:
    • Waste Products: CO2 (excreted via lungs), other waste via kidneys

ECF Cycle

• ECF circulates via blood:
  • From heart in arteries → Capillaries → Diffusion to tissues → Veins → Back to heart
• ECF is present throughout the body.

Intracellular Fluid Components

• Water and Ions:
  • Different ions compared to ECF:
    • Potassium, Magnesium, Phosphate are prevalent
    • Sodium and chloride more common in ECF
  • Ion flow is regulated, maintaining concentration differences.

Upcoming Topics

• Homeostasis: To be discussed in the next video.
• Not to be confused with Hemostasis.

Additional Information

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