Human Physiology: The Science of Life in Action

Physiology is the study of life processes in humans, animals, and plants. Human physiology focuses on how organs, tissues, and cells interact to sustain life. It explains the body’s homeostasis, or its ability to maintain stable internal conditions despite external changes.

Major Systems Studied in Physiology

1. Cardiovascular Physiology

• Studies the heart, blood, and blood vessels.

• Explains how oxygen and nutrients are transported to tissues and how waste is removed.

• Helps understand blood pressure regulation, heart rate, and circulation efficiency.

2. Respiratory Physiology

• Focuses on lungs and breathing.

• Examines how oxygen enters the blood, carbon dioxide is expelled, and how the body adapts to high altitudes or exercise.

3. Digestive Physiology

• Explains how food is broken down, absorbed, and converted into energy.

• Studies enzyme activity, nutrient absorption, and waste elimination.

4. Neurophysiology

• Examines the brain, spinal cord, and nerves.

• Studies how neurons communicate, how reflexes occur, and how the nervous system regulates voluntary and involuntary actions.

5. Endocrine Physiology

• Focuses on hormone-producing glands like the thyroid, pancreas, and adrenal glands.

• Explains how hormones regulate metabolism, growth, reproduction, and stress responses.

6. Muscle and Exercise Physiology

• Studies how muscles contract, generate force, and respond to exercise.

• Explains energy metabolism, oxygen use, and fatigue during physical activity.

7. Renal & Excretory Physiology

• Examines how the kidneys filter blood, maintain fluid balance, and remove waste.

• Explains urine formation, electrolyte balance, and blood pressure regulation.

8. Reproductive Physiology

• Studies the reproductive organs and hormones.

• Explains processes like ovulation, sperm production, fertilization, and pregnancy.