The Nervous System and Endocrine System

While neurons are the building blocks of the body’s communication system, it is the network of neurons that allow signals to move between the brain and body. These organized networks, composed of up to 1 trillion neurons, make up what is known as the nervous system.

The human nervous system has two parts: the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, which is composed of nerves and nerve networks throughout the body.

The endocrine system is also essential to communication. The system utilizes glands located throughout the body that secrete hormones. The hormones regulate a variety of bodily functions, including metabolism, digestion, blood pressure, and growth. The endocrine system is not directly linked to the nervous system, but the two interact in a number of ways.

The Central Nervous System

The central nervous system (CNS) is made up of the brain and spinal cord. The primary form of communication in the CNS is the neuron. Together, the brain and the spinal cord are the literal "center" of the body’s communication system.

The brain and spinal cord are vital to human life and functioning.

The body employs a number of protective barriers to surround them, including the bone (skull and spine) and membraneous tissue known as meninges. The brain and spine are suspended in a protective liquid known as cerebrospinal fluid.

The CNS is responsible for processing every sensation and thought that you experience. The sensory information that is gathered by receptors throughout the body. It then passes the information on to the central nervous system. The CNS also sends messages to the rest of the body to control movement, actions, and responses to the environment.

The Peripheral Nervous System

The peripheral system (PNS) is composed of nerves that extend outside of the central nervous system. The nerves and nerve networks that make up the PNS are actually bundles of axons from neuron cells. The nerve bundles can be relatively small or large enough to be easily seen by the human eye.

The PNS is further divided into two different systems: the somatic nervous system and the autonomic nervous system.

Somatic Nervous System

The somatic nervous system transmits sensory communications. It is responsible for voluntary movement and action. It is composed of sensory (afferent) neurons and motor (efferent) neurons.

Sensory neurons carry information from the nerves to the brain and spinal cord while motor neurons transmit information from the central nervous system to the muscle fibers.

Autonomic Nervous System

The autonomic nervous system is responsible for controlling involuntary functions such as heartbeat, respiration, digestion, and blood pressure. The system is also involved in human emotional responses such as sweating and crying.

The autonomic nervous system is subdivided into the sympathetic nervous system and parasympathetic nervous system.

  • Sympathetic nervous system: The sympathetic nervous system controls the body’s response to an emergency. When the system is aroused, your heart and breathing rates increase, digestion slows or stops, the pupils dilate and you begin to sweat. Also known as the fight-or-flight response, the system is preparing your body to either fight the danger or flee.
  • Parasympathetic nervous system: The parasympathetic nervous system counters the sympathetic system. After a crisis or danger has passed, the system helps to calm the body by slowing heart and breathing rates, resuming digestion, contracting the pupils, and stopping sweating.

The Endocrine System

The endocrine system is composed of glands that secrete chemical messengers known as hormones. Hormones are carried in the bloodstream to specific areas of the body, including the organs and body tissues.

The pineal gland, the hypothalamus, the pituitary gland, the thyroid, the ovaries, and the testes are some of the most important glands in the body. Each of these glands works in a number of unique ways in specific areas.

The endocrine system is not a part of the nervous system, but it is still essential to communication throughout the body.

The hypothalamus connects these two important communication systems. The hypothalamus is a tiny collection of nuclei that is responsible for controlling an astonishing amount of human behavior.

Located at the base of the forebrain, the hypothalamus regulates basic needs such as sleep, hunger, thirst, and sex drive. It's also involved in producing our emotional and stress responses. The hypothalamus controls the pituitary glands, which, in turn, controls the release of hormones from other glands that are part of the endocrine system.

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