Interoceptors:

Interoceptors are sensory receptors within our bodies that recognize and respond to internal changes. They are associated with the autonomic nervous system (part of the peripheral nervous system/PNS that regulates involuntary physiologic processes, like heartrate, blood pressure, respiration, digestion, sexual arousal). Interoceptors are particularly attuned to our organs (heart, lungs, digestive organs) and blood vessels (changed temperature, blood pressure, blood pH)—that we recognize when thirsty, hungry, in pain, or nauseous.