ANP 1105 Lecture Notes - Lecture 15: Ketone Bodies, Intercostal Nerves, Brain Ischemia

• School: University of Ottawa
• Department: Anatomy and Physiology
• Course: ANP 1105
• Professor: William Staines

Document Summary

Indicate the influences of pco2, po2 and arterial ph on respiration rate. Most important: changing levels of co2, o2, h+ Peripheral receptors only weakly influenced by pco2; regulation is via medullary chemoreceptors. Co2 to cerebrospinal fluid hydrated to carbonic acid liberates h+ (cs fluid cannot buffer) ph of cs fluid drops, exciting central chemoreceptors increased rate & depth of breathing. Hyperventilation is self-limiting: ends when pco2 back to normal. Note that h+ is trigger for chemoreceptors (even though initiated by increased. Co2); . control of breathing during rest is aimed primarily at regulating [h+] in brain . Arterial oxygen sensors in aortic arch & carotid bodies. Small changes just increase sensitivity of receptors to pco2. Need large drop in po2 (to < 60 mm hg) before a major stimulus increases ventilation (hb saturated at po2 > 60 mmhg) Clinical application: emphysema, chronic bronchitis: chronically elevated pco2 chemoreceptors become nonresponsive & po2 takes over.