CONTROL OF BREATHING

The control of breathing is mainly through central and peripheral chemoreceptors.

 The peripheral chemoreceptors are located in the carotid bodies (at the bifurcation of the common carotid arteries) and in the aortic bodies(in the aortic arch). The peripheral chemoreceptors control concentration of O2 and pH. 

The central chemoreceptors are located on the surface of the medulla and control concentration of CO2 . 

Terminal and respiratory bronchioles of the lungs contain mechanoreceptors of vagus nerves. With their significant extension (deep intensified breath) afferentation from the lungs to the centers of medulla oblongata increases sharply; it causes inhibition of breathing due to increased tone of vagus nerves. This reaction is named as Respiratory reflex (=pulmonary stretch Reflex=Hering-Breuer reflex). 

The main components of the central nervous system controller for ventilation are located in spinal cord, neurons in the medulla and pons, cortex.

Spinal regulation 

Vegetative nucleuses in lateral horns of the spinal cord cause autonomic nervous system regulation (mainly during “fight or flight” responses - pain, high body temperature, arterial blood pressure). 

Outflow from the medullary centers reaches the muscles of ventilation via somatic motor neurons. 

A central pattern generator in the medulla and pons initiates the basic rhythmic pattern of breathing, which proceeds without the need for conscious control (e.g., during sleep). Mainly these nerve centers consist of the pacemaker nerve cells.

Cortex of the brain causes control of respiration according the emotional activity, reflexes or voluntary control (speech, singing, voluntary holding).