Question

Explain how the chemosensitive area in the medulla function. That is, what stimulates it and how does it respond?

Answer 1

There are two types of chemoreceptors.

i. central chemoreceptors

ii. peripheral chemoreceptors.

Central chemoreceptors located in medulla oblongata and are responsible and sensitive to changes in hydrogen ion concentration and carbondioxide concentration.

peripheral chemoreceptors are located in corotid artery and aorta and are responsible for changes in concentration carbondioxide and oxygen in the blood.

the central chemoreceptors regulate the normal pH value and normal partail pressure of carbondioxide in blood achieved by increasing respiration and increased ventillation.

The chemoreceptors send the information to medulla oblongata through Cranial nerve IX and X.

The conditions which stimulate the central chemoreceptors are Hypercapnia and acidemia.

Hypercapnia causes increased firing of chemoreceptors and increases the respiration and ventillation that decreases the partial pressure of carbondioxide to normal.

Acidemia is a condition of decreased PH value that causes the increased firing of respiratory neuronal activity,increases rate of respiration and ventillation that removes carbondioxide and brings the partial pressure of carbondioxide and PH to normal value.