Physiology 2130 Lecture Notes - Lecture 10: External Intercostal Muscles, Respiratory Center, Internal Intercostal Muscles
22 Jan 2017
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Document Summary
Breathing can be spontaneous (majority of the time) or voluntary: can increase, decrease or stop ventilation at anytime. Spontaneous respiration originates in the medullary respiratory center of the medulla oblongata of the brainstem: produced by rhythmic activity from the neurons (like the pacemaker of the heart, exact mechanism causing nerves to fire is unclear. Voluntary center is located in the cerebral cortex: voluntary system is capable of overriding the center in the brain stem, example: holding your breath. The medullary respiratory center in the medulla oblongata contains 2 areas: Inspiratory center: activates the inspiratory muscles (during inhalation: expiratory center: activates the expiratory muscles (during active exhalation) Inspiration is always an active process requiring the contraction of the diaphragm and external intercostal muscles. The inspiratory center stimulates the contraction of these inspiratory muscles and inhibits the expiratory center. The control for exhalation is different than inspiration.
