Overview
This lecture explains the structure and function of the respiratory system, detailing the pathway of air from entry to gas exchange.
Functions of the Respiratory System
- The respiratory system transports air into the lungs.
- It diffuses oxygen into the bloodstream and removes carbon dioxide from it.
Structure of the Respiratory System
- The system is divided into upper and lower respiratory tracts.
Upper Respiratory Tract
- Air enters through the mouth or nose and passes through the nasal cavity.
- The nasal cavity filters, warms, and moistens incoming air.
- Air moves next to the pharynx and then into the larynx (voice box).
Lower Respiratory Tract
- Air passes from the larynx into the trachea (windpipe).
- The trachea's inner membrane has cilia (tiny hair cells) that trap dust particles, which are expelled by coughing.
- The trachea has 15 to 20 C-shaped cartilage rings in front and on the sides to keep it open and protected.
Bronchi and Lungs
- The trachea divides into two tubes called bronchioles when entering the lungs.
- Inside the lungs, bronchi branch into smaller tertiary bronchi.
- Tertiary bronchi further branch into bronchioles, which are less than one millimeter wide.
- Air travels through bronchioles into alveolar sacs and alveoli.
Gas Exchange
- Gas exchange takes place in the alveoli, where oxygen enters the blood and carbon dioxide leaves it.
Key Terms & Definitions
- Pharynx — Passageway after the mouth/nose that leads to the larynx.
- Larynx — The voice box; connects the pharynx to the trachea.
- Trachea — The windpipe; carries air to the bronchi, supported by cartilage rings.
- Cilia — Tiny hair-like structures in the trachea that trap dust.
- Bronchi/Bronchioles — Airways branching from the trachea into the lungs; bronchioles are the smallest branches.
- Alveoli — Small air sacs in the lungs where gas exchange occurs.
Action Items / Next Steps
- Review the pathway of air from entry to alveoli.
- Learn the functions of each respiratory structure.