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Anatomy of the Cough

A cough is a normal part of human life, and even though it’s unpleasant, annoying, and disruptive, it’s also an important defense mechanism for your body.1,2

Step 1 – The set up

Special sensory proteins called “receptors” are found on the surface of some cells that line the upper respiratory tract2,3 in places like the back of the throat, the trachea (windpipe), and the upper bronchi where the trachea branches into the lungs. When these receptors are stimulated, they send information to the brain.

Step 2 – The Cough Centre

When your brain’s cough centre (the part of the brain that takes care of your throat and upper airways) gets information from the receptors, it decides whether it’s time to cough. If it gets a signal that the lining of the airway is irritated, muscles in the throat and chest receive action signals that trigger the cough.

Step 3 – The cough

When the brain sends the signal, the cough begins! The actual cough is a three-step process.

  • First, you inhale.
  • Second, the opening to the trachea (the epiglottis) closes as the chest constricts, compressing the air within the lungs.
  • Third, the epiglottis opens, letting out a rapid burst of air through the mouth.

Why all the phlegm?

During a cold, mucus production in the airways increases, and coughing is how the body gets rid of the excess mucus so it doesn’t accumulate in the airways and lungs.

How can I stop feeling like I have to cough?

When your cough is caused by non-chronic illness, there are some non-prescription products that can help relieve your cough and chest congestion (see Table 1).2

Centrally acting cough suppressant medications can act directly on the brain’s cough center2 to reduce the sensitivity to prevent triggering a cough. The most common of these is dextromethorphan (DM).

Another class of ingredients is expectorants like guaifenesin, which helps to make mucus thinner and easier to clear from the airways.2 The soothing action of a liquid cough medication can also help provide relief because it can coat the throat to help reduce the irritation that is signaling the brain’s cough center.4

An understanding of the anatomy of cough and the nature of the cough reflex is an important part of knowing how to best provide relief.

Table 1. Different Approaches to treat an Acute Cough and Chest Congestion
Class of ingredient Mechanism of action
Centrally acting cough suppressant
(eg., dextromethorphan)
Inhibits activity at sites in the brain
Expectorant (eg., guaifenesin) Thins mucus, making it easier to clear


  1. Dicpinigaitis PV, Colice GL, Goolsby MJ, Rogg GI, Spector SL, Winther B. Acute cough: a diagnostic and therapeutic challenge. Cough. 2009; 5:11.
  2. Nosalova, Mokry, Franova. Pharmacological modulation of cough reflex. Advances in Phytomedicine. Volume 2, Pages 87-110. 2006
  3. Irwin RS, Rosen MJ, Braman SS. Cough. A comprehensive review. Arch Intern Med. 1977;137(9):1186-1191.
  4. Eccles R. Mechanisms of the placebo effect of sweet cough syrups. Respir Physiol Neurobiol. 2006;152(3):340-348.