Overview
This lecture explains the process of breathing, the structure of the respiratory system, and how the autonomic nervous system controls respiration.
The Role of Breathing
- Breathing delivers oxygen to body cells and removes carbon dioxide waste.
- It is an involuntary process managed by the autonomic nervous system.
Structure of the Respiratory System
- The respiratory system includes the lungs and other organs that move air in and out.
- The diaphragm and intercostal muscles help expand and contract the lungs.
- Air enters via the nose and mouth, travels through the trachea, and branches into bronchi.
- Bronchi divide into smaller tubes called bronchioles, which reach deep into the lungs.
- Lungs are spongy, not hollow, containing parenchyma tissue filled with bronchioles.
- At the end of each bronchiole are alveoli (tiny air sacs) surrounded by capillaries.
Gas Exchange Process
- Inhaled air fills alveoli, which are wrapped in capillaries full of red blood cells.
- Hemoglobin in red blood cells binds with oxygen from the alveoli.
- Carbon dioxide in capillaries diffuses into alveoli to be exhaled.
- Gas exchange occurs by diffusion, moving from areas of higher to lower concentration.
Control of Breathing
- The autonomic nervous system automatically signals breathing muscles.
- For inhalation, the diaphragm flattens and intercostal muscles contract, expanding lungs.
- For exhalation, these muscles relax, compressing the lungs and expelling air.
- This breathing cycle repeats 15-25 times per minute, moving about 10,000 liters of air daily.
Key Terms & Definitions
- Autonomic Nervous System — brain system that automatically controls vital functions such as breathing.
- Diaphragm — dome-shaped muscle below the lungs that helps with inhalation and exhalation.
- Intercostal Muscles — muscles between ribs that assist with expanding and compressing the lungs.
- Trachea — windpipe; the main airway leading to the lungs.
- Bronchi — main tubes that branch from the trachea into each lung.
- Bronchioles — small branches of the bronchi within the lungs.
- Alveolus (pl. alveoli) — tiny air sac in the lung where gas exchange happens.
- Capillaries — tiny blood vessels surrounding alveoli for gas exchange.
- Hemoglobin — protein in red blood cells that carries oxygen.
Action Items / Next Steps
- Review the process of gas exchange in the alveoli.
- Study key respiratory system terms and their functions.