Respiratory Regulation Of Ph

Reflex changes in ventilation help to defend blood pH. By changing the Pco2 and, hence, [H2CO3] of the blood, the respiratory system can rapidly and profoundly affect blood pH. As discussed in Chapter 22, a fall in blood pH stimulates ventilation, primarily by acting on peripheral chemoreceptors. An elevated arterial blood Pco2 is a powerful stimulus to increase ventilation,- it acts on both peripheral and central chemoreceptors, but primarily on the latter. CO2 diffuses into brain interstitial and cerebrospinal fluids, where it causes a fall in pH that stimulates chemoreceptors in the medulla oblongata. When ventilation is stimulated, the lungs blow off more CO2, making the blood less acidic. Conversely, a rise in blood pH inhibits ventilation,- the consequent rise in blood [H2CO3] reduces the alkaline shift in blood pH. Respiratory responses to disturbed blood pH begin within minutes and are maximal in about 12 to 24 hours.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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