RESPIRATORY PHYSIOLOGY RESPIRATORY SYSTEM - 2 RESPIRATORY PHYSIOLOGY

Brain Stem Respiratory Centers SEQUENCE: Voluntary (cerebral cortex) or involuntary (Pons and medulla) Pons (apneustic and pneumotaxic) Medulla (rhythmicity ctrs) Pre-Botzinger Inspiratory Expiratory Exercise related Motor neurons in dorsal/ventral respiratory group Activate/inh spinal nerves Diaphragm contracts

Sensory Input From Aortic and Carotid Bodies Central chemoreceptors: in medulla oblongata Peripheral chemoreceptors: in aortic and carotid bodies Sense carbon dioxide levels Send sensory information to medulla oblongata

Regulation of Ventilation by the CNS

Effects of PCO2 on Ventilation Hypercapnia = high CO2 Hypocapnia = low CO2

Chemoreceptors in the Medulla Central chemoreceptors respond to CO2, but not in the blood

Regulation of Breathing in Response to CO2 Levels

Comparing the effects of blood CO2 and O2 on breathing Hypoxic drive p. 558

Pulmonary Receptors can also have an effect on ventilation. 1) Unmyelinated C fibers are sensory neurons that are stimulated by capsaicin, which produces temporary apnea (cessation of breathing), followed by rapid, shallow breathing. 2) Irritant Receptors (rapidly adapting receptors) in the wall of the larynx, cause a person to cough (due to smoke, particulate matter), and an increase in pulmonary interstitial fluid. 3) Hering-Breuer reflex is stimulated by pulmonary stretch receptors. - important in maintaining normal ventilation in the newborn - may contribute to respiratory control at high tidal volumes, such as during exercise