What has the primary responsibility for sensing and responding to ...

[cagreen833]

What has the primary responsibility for sensing and responding to changes in blood levels of CO2?
 
  a. Apneustic centers
  b. Central chemoreceptors
  c. Peripheral chemoreceptors
  d. Pneumotaxic center

Question 2

In the face of chronically elevated levels of CO2, what happens to the response mediated by the central chemoreceptors?
 
  a. It is accentuated or increased.
  b. It is muted or decreased.
  c. There is no change in the response.
  d. There is no way to predict the body's re-sponse.

[helenmarkerine]

Answer to Question 1

ANS: B
Hydrogen ions stimulate highly responsive chemosensitive nerve cells, located bilaterally in the medulla. Nevertheless, these central chemoreceptors are extremely sensitive to CO2 in an indirect fashion. Through the hydrolysis reaction, as CO2 increases there is a greater release of hydrogen ions to which the chemoreceptors respond.

Answer to Question 2

ANS: B
The stimulatory effect of chronically high CO2 on the central chemoreceptors gradually declines over 1 or 2 days, because the kidneys retain bicarbonate ions in response to respiratory acidosis, bringing the blood pH level back toward normal.

[cagreen833]

TYSM

[parker125]

Excellent