Every cell in your body needs oxygen (O2). The respiratory system contains the major organs that are responsible for helping you breathe. The respiratory system also functions to remove the cellular waste product called carbon dioxide (CO2). All this also helps to maintain the acid-base balance in the body. Portions of the respiratory system are also used for non-vital functions such smell and speech production. This is accomplished through breathing, or the movement of air in and out of the lungs. Image 1 shows the major structures of the respiratory system. Image 2 illustrates the movement of air in (inhalation) and out (exhalation) during breathing.

There are five functions of the respiratory system.

  • Gas Exchange – oxygen and carbon dioxide
  • Breathing – movement of air
  • Sound Production
  • Olfactory Assistance – sense of smell
  • Protection – from dust and microbes entering body through mucus production, cilia, and coughing


Check Your Understanding

-The muscles for breathing are the intercostal muscles of the ribs and the ______.

-The functions of the respiratory system include gas exchange, sound production, olfactory assistance, protection, and ___________ (or the movement of air).

-True or False: The respiratory function of gas exchange and breathing help to maintain homeostasis of acid-base balance or pH levels in the body.

-What role do cilia of epithelial cells lining the respiratory tract play?

The 3 Major Parts of the Respiratory System

The respiratory system can be divided into 3 major parts:

1. airway - includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles

    a. Carries air between the lungs and the body's exterior.

2. lungs – a left lung with 2 lobes and a right lung with 3 lobes

    a. Act as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide out of the body.

3. muscles of respiration – intercostal muscles (muscle between ribs) and the diaphragm

a. Push air into and out of the lungs during breathing.

Check Your Understanding

-The 3 major parts of the respiratory system can be divided into the airway, lungs, and ____.

-How many lobes does the left lung have?

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