A chemoreceptor is a type of sensory receptor that detects chemical stimuli in the environment. These receptors are found in various organisms, including humans, and play a crucial role in sensing changes in chemical concentrations, such as oxygen, carbon dioxide, and pH levels. They help regulate vital functions like breathing and blood circulation by sending signals to the brain. In humans, chemoreceptors are primarily located in the carotid arteries and aorta, where they monitor blood chemistry. There are two main types: central chemoreceptors, which respond to changes in the brain's fluid, and peripheral chemoreceptors, which respond to changes in blood composition.