Chemoreceptors Detect Changes in Pco2 pH and Po2

The reflex response to changes in blood gases and pH begins with chemoreceptors located peripherally in the carotid bodies and aortic bodies and centrally in the medulla (see Chapter 22). The peripheral chemoreceptors of the carotid bodies and aortic bodies are specialized structures located in approximately the same areas as the carotid sinus and aortic baroreceptors. They send nerve impulses to the NTS and are sensitive to elevated Pco2, as well as decreased pH and Po2. Peripheral chemoreceptors exhibit an increased firing rate when (1) the Po2 or pH of the arterial blood is low, (2) the Pco2 of arterial blood is increased, (3) the flow through the bodies is very low or stopped, or (4) a chemical is given that blocks oxidative metabolism in the chemoreceptor cells. The central medullary chemoreceptors increase their firing rate primarily in response to elevated arterial Pco2, which causes a decrease in brain pH.

The increased firing of both peripheral and central chemoreceptors (via the NTS and RVL) leads to profound peripheral vasoconstriction. Arterial pressure is significantly elevated. If respiratory movements are voluntarily stopped, the vasoconstriction is more intense and a striking bradycardia and decreased cardiac output occur. This response pattern is typical of the diving response (discussed later). As in the case of the baroreceptor reflex, the coronary and cerebral circulations are not subject to the sympathetic vasoconstrictor effects and instead exhibit vasodila-tion, as a result of the combination of the direct effect of the abnormal blood gases and local metabolic effects.

In addition to its importance when arterial blood gases are abnormal, the chemoreceptor reflex is important in the cardiovascular response to severe hypotension. As blood pressure falls, blood flow through the carotid and aortic bodies decreases and chemoreceptor firing increases— probably because of changes in local Pco2, pH, and Po2.

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Essentials of Human Physiology

Essentials of Human Physiology

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Responses

  • isembard
    Which receptors detect a fall in po2?
    8 years ago
  • TOM
    What increases respiratory rate among pco2 arterial pressure ph po2?
    8 years ago
  • Adalberta
    What are the receptors that detect change in pco2?
    8 years ago
  • aleena
    What detects changes in blood ph?
    8 years ago
  • elisa
    What is chemoreceptors responce to changes pco2?
    8 years ago
  • Laura
    What chemoreceptor detects po2 of arterial blood?
    8 years ago
  • Michael
    Where is chemoreceptors located?
    8 years ago
  • Lena
    What changes occur in central and peripheral chemoreceptors when ph falls to 7.25?
    7 years ago
  • hugo
    How chemoreceptors detects changes in fatty acids?
    3 years ago
  • teodros amanuel
    What type of receptors responds to changes in PCO2?
    3 years ago
  • tom baier
    Which receptors detect increases in pco2?
    3 years ago
  • benjamin
    Which receptors will detect the increases in pco2 and decreases in co2 in the blood?
    3 years ago
  • pasqualina
    Which receptor detects the increase in the pco2 and decrease in the po2 in the blood?
    2 years ago
  • mari
    How body detect po2 in blood?
    2 years ago
  • almaz yohannes
    Do peripheral chemoreceptor rspond to change in PO2?
    2 years ago
  • laura bar
    Which type of receptor detects changes in the body's pH?
    1 year ago
  • bilcuzal
    What receptors detects drop in testosterone levels?
    1 year ago
  • leon oster
    Does a large decrease in po2 stimulate any receptors?
    1 year ago
  • jasper
    When chemoreceptors detect an increase in pco2, the respiratory rate will?
    1 year ago
  • p
    How are changes in pco2 detected by chemoreceptros?
    12 months ago
  • yolanda
    What is the response to a increase of pco2?
    12 months ago
  • Anna
    Where are blood ph receptors found?
    11 months ago
  • Ted
    Does the medulla sense ph change?
    3 months ago
  • BILLY
    How does the body detect change in arterial po2?
    3 months ago
  • Berylla
    How does body detect ph centrally and peripherally?
    12 days ago

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