Editing Lung (section)

=== Nerve supply ===
The lungs are supplied by nerves of the [[autonomic nervous system]]. Input from the [[parasympathetic nervous system]] occurs via the [[vagus nerve]].<ref name="Moore K"/> When stimulated by [[acetylcholine]], this causes constriction of the smooth muscle lining the bronchus and bronchioles, and increases the secretions from glands.<ref name="Levitzky2013_2">{{cite book|last1=Levitzky|first1=Michael G.|title=Pulmonary physiology|date=2013|publisher=McGraw-Hill Medical|location=New York|isbn=978-0-07-179313-1|chapter= Chapter 2. Mechanics of Breathing |edition=8th}}</ref>{{page needed |date=January 2018}} The lungs also have a sympathetic tone from [[norepinephrine]] acting on the [[Beta-2 adrenergic receptor|beta 2 adrenoceptors]] in the respiratory tract, which causes [[bronchodilation]].<ref name="Johnson">{{cite journal | vauthors = Johnson M | title = Molecular mechanisms of beta(2)-adrenergic receptor function, response, and regulation | journal = The Journal of Allergy and Clinical Immunology | volume = 117 | issue = 1 | pages = 18–24; quiz 25 | date = January 2006 | pmid = 16387578 | doi = 10.1016/j.jaci.2005.11.012 | doi-access = free }}</ref>

The action of breathing takes place because of nerve signals sent by the [[respiratory center]] in the [[brainstem]], along the [[phrenic nerve]] from the [[cervical plexus]] to the diaphragm.<ref>{{Cite book|title=Principles of Anatomy & Physiology|last1=Tortora|first1=G|last2=Derrickson|first2=B|publisher=Wiley|year=2011|isbn=9780470646083|pages=504}}</ref>