Respiratory physiology: Lung receptors

Pulmonary receptors

There are a number of key receptors in the lung which play a role in the control of respiration:

• Stretch receptors
• Juxtacapillary receptors
• Irritant receptors

Stretch receptors
Pulmonary stretch receptors are mechanoreceptors found in the smooth muscle of the bronchi and bronchioles of the lungs.

When triggered these stretch receptors send action potentials via myelinated fibres of the vagus nerve to the inspiratory area in the medulla and apneustic centre of the pons. These impulses directly inhibit the inspiratory area and inhibit the apneustic centre from activating the inspiratory area (therefore slowing respiratory rate). This inhibits inspiration, allowing expiration to occur. This is known as the Hering-Breuer reflex



J receptors
Juxta-pulmonary capillary receptors are also known as J-receptors, Juxtacapillary receptors and pulmonary C-fibre receptors.


J-receptors respond to several stimuli including:

• Pulmonary congestion/oedema
• Pulmonary emboli
• Lung inflammation e.g. pneumonia
• Hyperinflation (barotrauma)

The stimulation of the J-receptors causes the following reflex response:

• Apnoea followed by rapid breathing (tachypnoea)
• Bradycardia
• Hypotension
• Sensation of dyspnoea

Irritant receptor
Irritant receptors are located throughout the respiratory epithelium. They are sensitive to both mechanical and chemical stimuli e.g. histamine, bradykinin, and prostaglandins. The stimulation of irritant receptors will typically lead to cough and bronchoconstiction.