Respiratory System Structures

The respiratory system is essential for breathing and gas exchange, involving various structures that work together. From the nasal cavity to the alveoli, each part plays a unique role in ensuring efficient airflow and oxygen delivery throughout the body.

1. Nasal cavity

   • Warms, moistens, and filters incoming air.
   • Contains olfactory receptors for the sense of smell.
   • Divided by the nasal septum into left and right sides.

2. Pharynx

   • Connects the nasal cavity and mouth to the larynx and esophagus.
   • Divided into three regions: nasopharynx, oropharynx, and laryngopharynx.
   • Plays a role in both respiratory and digestive systems.

3. Larynx

   • Also known as the voice box; located below the pharynx.
   • Contains the vocal cords, which vibrate to produce sound.
   • Acts as a passageway for air and prevents food from entering the trachea.

4. Trachea

   • A tube that connects the larynx to the bronchi.
   • Reinforced with C-shaped cartilage rings to maintain open airways.
   • Lined with ciliated mucosa to trap and expel debris.

5. Bronchi

   • The trachea divides into the right and left bronchi, leading to each lung.
   • Further branches into smaller bronchi and bronchioles.
   • Conducts air to the lungs and helps in the distribution of air.

6. Bronchioles

   • Smallest air passages in the lungs, leading to alveoli.
   • Lack cartilage; walls are made of smooth muscle for regulation of airflow.
   • Play a crucial role in gas exchange by directing air to alveoli.

7. Alveoli

   • Tiny air sacs where gas exchange occurs.
   • Surrounded by pulmonary capillaries for oxygen and carbon dioxide exchange.
   • Increase surface area for efficient gas exchange.

8. Lungs

   • Paired organs located in the thoracic cavity, responsible for respiration.
   • Contain bronchi, bronchioles, and alveoli.
   • Enclosed by pleura and divided into lobes (three on the right, two on the left).

9. Pleura

   • Double-layered membrane surrounding the lungs.
   • Provides lubrication and reduces friction during breathing.
   • Helps maintain pressure gradient for lung expansion.

10. Diaphragm

    • A dome-shaped muscle located at the base of the thoracic cavity.
    • Contracts and flattens during inhalation, increasing thoracic volume.
    • Plays a key role in the mechanics of breathing.

11. Intercostal muscles

    • Located between the ribs; assist in the expansion and contraction of the thoracic cavity.
    • External intercostals aid in inhalation, while internal intercostals assist in exhalation.
    • Help maintain the structural integrity of the rib cage during breathing.

12. Epiglottis

    • A flap of cartilage located at the base of the tongue.
    • Closes over the larynx during swallowing to prevent food from entering the airway.
    • Plays a protective role in directing air and food to the correct passages.

13. Vocal cords

    • Located within the larynx; vibrate to produce sound when air passes through.
    • Tension and length can be adjusted to change pitch and volume.
    • Essential for speech and communication.

14. Pulmonary capillaries

    • Tiny blood vessels surrounding the alveoli.
    • Facilitate the exchange of oxygen and carbon dioxide between blood and air.
    • Play a critical role in maintaining blood oxygen levels.

15. Cilia

    • Microscopic hair-like structures lining the respiratory tract.
    • Move in a coordinated manner to sweep mucus and trapped particles out of the airways.
    • Help keep the respiratory system clear of debris and pathogens.