Question

Terri has diabetes mellitus and, as a side effect, has developed ketoacidosis. The ketones are making Terri’s blood too acidic (decreasing the pH of her blood). Chemoreceptors in Terri’s medulla oblongata (part of the brain stem) detect this change and send an electrical message to her respiratory system. Terri will start to breath faster, increasing the release of more CO₂ than normal. Since CO₂ forms an acid in the blood, releasing more CO₂ will bring the blood pH back to normal.

What is the stimulus in this situation?

• low blood pH (blood too acidic)

• breathing faster

• chemoreceptors

• respiratory system

• medulla oblongata

Terri has diabetes mellitus and, as a side effect, has developed ketoacidosis. The ketones are making Terri’s blood too acidic (decreasing the pH of her blood). Chemoreceptors in Terri’s medulla oblongata (part of the brain stem) detect this change and send an electrical message to her respiratory system. Terri will start to breath faster, increasing the release of more CO₂ than normal. Since CO₂ forms an acid in the blood, releasing more CO₂ will bring the blood pH back to normal.

What is the receptor in this situation?

• low blood pH (blood too acidic)

• medulla oblongata

• chemoreceptors

• respiratory system

• breathing faster

Terri has diabetes mellitus and, as a side effect, has developed ketoacidosis. The ketones are making Terri’s blood too acidic (decreasing the pH of her blood). Chemoreceptors in Terri’s medulla oblongata (part of the brain stem) detect this change and send an electrical message to her respiratory system. Terri will start to breath faster, increasing the release of more CO₂ than normal. Since CO₂ forms an acid in the blood, releasing more CO₂ will bring the blood pH back to normal.

What is the control center in this situation?

• respiratory system

• breathing faster

• low blood pH (blood too acidic)

• medulla oblongata

• chemoreceptors

Terri has diabetes mellitus and, as a side effect, has developed ketoacidosis. The ketones are making Terri’s blood too acidic (decreasing the pH of her blood). Chemoreceptors in Terri’s medulla oblongata (part of the brain stem) detect this change and send an electrical message to her respiratory system. Terri will start to breath faster, increasing the release of more CO₂ than normal. Since CO₂ forms an acid in the blood, releasing more CO₂ will bring the blood pH back to normal.

What is the response of the effector in this situation?

• medulla oblongata

• chemoreceptors

• breathing faster

• low blood pH (blood too acidic)

• respiratory system

Answer 1

Rate, depth and rhythm of respiration are regulated by a group of neurons located in reticular formation of brain stem called respiratory centres. The respiratory centres are broadly classified into: (1) Medullary centres and (2) Pontine centres.

Medullary centres consist of two group of neurons: (1) Dorsal Respiratory Group (DRG) and (2) Ventral Respiratory Group (VRG). Pontine centres consist of: (1) Pneumotaxic Centre (PNC) and (2) Apneustic Centre (APC)

Regulation of respiration is mediated via two mechanisms: (1) Neural regulation and (2) Chemical regulation

Here, we're talking about chemical regulation of respiration. The major stimuli for chemical regulation are: (1) O₂ concentration (2) CO₂ concentration and (3) H+ concentration. An increase in concentration of CO₂ and H+ and decrease in concentration of O₂ will stimulate the receptors involved in chemical regulation called chemoreceptors.

Chemoreceptors are of two types: (1) Central chemoreceptors and (2) Peripheral chemoreceptors. The central chemoreceptors are located in ventral₂ part of medulla. The peripheral chemoreceptors are carotid body (two in number, each one located on either side of midline near bifurcation of common carotid artery) and aortic body (two or more in number, located near arch of aorta).

These chemoreceptors once stimulated send signals to pontomedullary respiratory centres which causes increased firing of neurons of diaphragm and inspiratory intercostals causing their increased contraction and therefore the ventilation. In this way, O_2, CO₂ and H+ concentration are brought to normal.

So, the answers to the above question are as follows:

Stimulus - low blood pH (blood too acidic)

Receptor - chemoreceptors

Control centre - medulla oblongata

Response - breathing faster

Hope you are clear now! Don't forget to rate my answer, thanks!