Our bodies are constantly sensing what is happening inside us, even when we are not aware of it. This internal awareness is known as interoception. Similar to homeostasis, the term interoception describes something we experience every day—the process through which the body monitors its internal environment and sends signals to the brain to maintain balance.

Most people are familiar with the five traditional senses: sight, hearing, taste, smell and touch. However, interoception can be thought of as a sixth sense that works quietly in the background. It continuously monitors internal conditions such as blood pressure, body temperature, and the balance of fluids and electrolytes in our body. These signals are constantly communicated to our brain so our body can respond appropriately and maintain stability.

Despite how important interoception is, it’s often overlooked when we discuss how the body functions. We often focus on organs performing their individual tasks, such as the heart pumping blood or the lungs exchanging oxygen. We talk less often about how the brain becomes aware of what is happening inside the body in the first place. Interoception is the network that allows our brain and organs to remain connected and coordinated.

One fascinating example of this internal communication involves the relationship between the kidneys and the brain. Most of the time, we are not consciously aware of our kidneys filtering blood or regulating electrolyte levels, yet we experience the consequences of their function. The kidneys do much more than remove waste products from the blood. They also act as sensors that constantly monitor levels of salt, water and other substances in the body.

When these levels change, signals are transmitted to the brain to help restore balance. For example, when you become dehydrated, receptors detect changes in fluid balance and trigger the sensation of thirst. Similarly, small changes in blood pressure or electrolyte levels can trigger hormone release, constrict blood vessels and even make us crave salt. Through these signals—most of which we don’t often notice—the kidneys help the body maintain homeostasis.

Learning about these internal sensing pathways has helped me appreciate how organs communicate to regulate the body. The kidney–brain connection shows that the body is not just a group of separate organs, but a system that works together by constantly sharing information. Understanding this communication can help us learn more about diseases like hypertension and chronic kidney disease and may lead to better treatments.