Functions of the Respiratory System

Functions of the Respiratory System

- Inhalation and Exhalation Are Pulmonary Ventilation (breathing)

The respiratory system aids in breathing, also called pulmonary ventilation. In pulmonary ventilation, air is inhaled through the nasal and oral cavities (the nose and mouth).

- External Respiration Exchanges Gases Between the Lungs and the Bloodstream

Inside the lungs, oxygen is exchanged for carbon dioxide waste through a process called external respiration. This respiratory process takes place through hundreds of millions of microscopic sacs called alveoli.

- Internal Respiration Exchanges Gases Between the Bloodstream and Body Tissues

The bloodstream delivers oxygen to cells and removes waste carbon dioxide through internal respiration, another key function of the respiratory system. In this respiratory process, red blood cells carry oxygen absorbed from the lungs around the body, through the vasculature.

- Air Vibrating the Vocal Cords Creates Sound

Phonation is the creation of sound by structures in the upper respiratory tract of the respiratory system. During exhalation, air passes from the lungs through the larynx, or “voice box.” When we speak, muscles in the larynx move the arytenoid cartilages. The arytenoid cartilages push the vocal cords, or vocal folds, together. When the cords are pushed together, air passing between them makes them vibrate, creating sound.

- Olfaction, or Smelling, is a Chemical Sensation

The process of olfaction begins with olfactory fibers that line the nasal cavities inside the nose. As air enters the cavities, some chemicals in the air bind to and activate nervous system receptors on the cilia. This stimulus sends a signal to the brain: neurons take the signal from the nasal cavities through openings in the ethmoid bone, and then to the olfactory bulbs. The signal then travels from the olfactory bulbs, along cranial nerve 1, to the olfactory area of the cerebral cortex.