What chemoreceptors are activated by low oxygen, high carbon dioxide, and low pH?

Chemoreceptors that are activated by low oxygen, high carbon dioxide, and low pH are primarily the peripheral chemoreceptors and central chemoreceptors.

1. Peripheral Chemoreceptors: These are located in the carotid bodies and aortic bodies. They are sensitive to changes in the oxygen (O2), carbon dioxide (CO2), and pH levels in the blood. When oxygen levels decrease, or when carbon dioxide levels increase or pH levels decrease (indicating an increase in acidity), these chemoreceptors send signals to the respiratory center in the brain to increase the rate and depth of breathing.

2. Central Chemoreceptors: These are located in the medulla oblongata of the brain. They primarily respond to changes in the concentration of carbon dioxide in the cerebrospinal fluid, which reflects the carbon dioxide levels in the blood. An increase in carbon dioxide levels or a decrease in pH will trigger these chemoreceptors to signal the respiratory center to increase breathing.

So, in summary, both peripheral and central chemoreceptors are activated by low oxygen, high carbon dioxide, and low pH, leading to an increase in the rate and depth of breathing to restore balance.