Respiratory System Structures to Know for Anatomy and Physiology II

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.