The nervous system and endocrine system are connected by the hypothalamus, which regulates hormones in the body. The hypothalamus controls major endocrine glands like the pituitary gland, and it also supports proper nervous system function.
The Endocrine System
The endocrine system controls hormones in the human body. Glands within the endocrine system secrete hormones, which are chemicals that move throughout the body. One of the most important glands in the endocrine system is the pituitary gland, which is a small, pea-sized organ located near the brain. Although it's among the smallest glands, the pituitary is one of the most important. The hypothalamus directly controls the pituitary gland, and it can direct the gland to start or stop hormone production. Hormones secreted by the hypothalamus include anti-diuretic hormones, growth hormones and oxytocin. The hypothalamus, working in conjunction with the pituitary gland, controls basic life functions like hunger, thirst, sleep, sex, stress and emotional responses.
Another important endocrine gland is the pancreas, which regulates the body's fuel system. Adrenal glands, located above the kidneys, regulate the body's salt and water levels. They're responsible for immune system function, metabolism and sexual development. Adrenal hormones prepare the body for action (also called the "fight or flight" instinct), and it's the nervous system's job to interpret those hormones and make the body act accordingly. Hormones produced by all of these endocrine system glands control feelings and emotions, and the body produces them constantly. After hormones are produced and dispatched, they travel to an end destination, which is either other glands or tissues. Upon receiving the first wave of hormones, the receptors may release additional hormones. This creates a complex system of chemical reactions that triggers a response from the nervous system. While hormones produced by all glands in the endocrine system trigger a response from the nervous system, the reproductive hormones released by endocrine glands directly affect the nervous system's development.
The Nervous System
While the endocrine system produces feelings and emotions through hormones, the nervous system produces the mechanisms for expressing those emotions. The nervous system, also called the electrical highway of the human body, divides into two parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord, and it is responsible for carrying out the body's most important functions. The CNS works by interpreting information from sensory organs and deciding how to act on that information. The spinal cord triggers voluntary and involuntary responses to stimuli, including fast reflexes. While the CNS acts as the body's communication center, the PNS contains glands, muscles and receptors that respond to information gathered by the CNS. The PNS breaks down further into two separate systems, which are the automatic nervous system (ANS) and the somatic nervous system (SNS). The ANS controls many internal body functions, like heart rate, perspiration and respiration. The SNS controls external parts of the body including muscles, skin and sensory organs. The CNS and PNS work together to maintain a balance in the body, called homeostasis. The hypothalamus plays a major role in maintaining that equilibrium by constantly measuring the body's state and working to correct imbalances that arise.