What type of receptors are responsible for monitoring the chemical composition of blood?

Chemoreceptors are specialized sensory receptors that detect changes in the chemical composition of the blood and other bodily fluids. They play a crucial role in monitoring various parameters, such as oxygen and carbon dioxide levels, as well as pH. These receptors are vital for maintaining homeostasis as they help regulate respiratory and cardiovascular functions in response to changing chemical conditions.

In the context of the options provided, photoreceptors are sensitive to light and are involved in vision, thermoreceptors detect changes in temperature, and mechanoreceptors respond to mechanical stimuli such as pressure or vibration. None of these function in the capacity of monitoring the chemical composition of blood, highlighting why chemoreceptors are the correct choice for this question.