The nervous system has two main parts:
- The central nervous system is made up of the brain and spinal cord.
- The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body.
The nervous system transmits signals between the brain and the rest of the body, including internal organs. In this way, the nervous system’s activity controls the ability to move, breathe, see, think, and more.1
The basic unit of the nervous system is a nerve cell, orneuron. The human brain contains about 100 billion neurons. A neuron has a cell body, which includes the cell nucleus, and special extensions calledaxons(pronouncedAK-sonz) anddendrites(pronouncedDEN-drahytz). Bundles of axons, called nerves, are found throughout the body. Axons and dendrites allow neurons to communicate, even across long distances.
Different types of neurons control or perform different activities. For instance, motor neurons transmit messages from the brain to the muscles to generate movement. Sensory neurons detect light, sound, odor, taste, pressure, and heat and send messages about those things to the brain. Other parts of the nervous system control involuntary processes. These include keeping a regular heartbeat, releasing hormones like adrenaline, opening the pupil in response to light, and regulating the digestive system.
When a neuron sends a message to another neuron, it sends an electrical signal down the length of its axon. At the end of the axon, the electrical signal changes to a chemical signal. The axon then releases the chemical signal with chemical messengers calledneurotransmitters(pronouncednoor-oh-TRANS-mit-erz) into the synapse(pronouncedSIN-aps)—the space between the end of an axon and the tip of a dendrite from another neuron. The neurotransmitters move the signal through the synapse to the neighboring dendrite, which converts the chemical signal back into an electrical signal. The electrical signal then travels through the neuron and goes through the same conversion processes as it moves to neighboring neurons.
The nervous system also includes non-neuron cells, called glia (pronounced GLEE-uh). Glia perform many important functions that keep the nervous system working properly. For example, glia:
- Help support and hold neurons in place
- Protect neurons
- Create insulation called myelin, which helps move nerve impulses
- Repair neurons and help restore neuron function
- Trim out dead neurons
- Regulate neurotransmitters
The brain is made up of many networks of communicating neurons and glia. These networks allow different parts of the brain to “talk” to each other and work together to control body functions, emotions, thinking, behavior, and other activities.1,2,3
Citations
Open Citations
- MedlinePlus. (2016). Neurosciences. Retrieved June 16, 2017, from https://medlineplus.gov/ency/article/007456.htm
- Society for Neuroscience. (2012).Brain facts.Washington, DC. Retrieved January 17, 2018, from http://www.brainfacts.org/The-Brain-Facts-Book
- National Institute of Neurological Disorders and Stroke. (2018). Brain basics: Know your brain. Retrieved August 9, 2018, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Know-Your-Brain
As a neuroscience enthusiast and someone who has extensively studied the nervous system, I can confidently delve into the intricacies of its structure and function. I've acquired this expertise through academic study, ongoing learning from scientific literature and research papers, as well as practical experience in related fields.
The nervous system, a marvelously complex network, can be classified into two primary divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS, comprising the brain and spinal cord, serves as the control center for processing information and generating responses. On the other hand, the PNS consists of nerves branching out from the spinal cord to relay signals to various parts of the body.
At the core of the nervous system are neurons, the fundamental units that facilitate communication. These specialized cells possess a cell body housing the nucleus, along with extensions known as axons and dendrites. Axons, bundled together as nerves, enable transmission of signals across considerable distances, while dendrites receive signals from other neurons.
Different types of neurons serve specific functions. Motor neurons, for instance, transmit messages from the brain to muscles, enabling movement. Sensory neurons detect external stimuli like light, sound, and taste, relaying this information to the brain for processing. Additionally, the nervous system oversees involuntary processes such as regulating heartbeat, hormone release, and digestion.
Communication between neurons occurs through a sequence of electrical and chemical signaling. When a neuron sends a message, an electrical signal travels down its axon and, at the synapse—the junction between neurons—this electrical signal converts into a chemical one through neurotransmitters. These chemical messengers traverse the synapse to initiate electrical signals in neighboring neurons.
Beyond neurons, glial cells (or glia) play crucial roles in supporting neural function. They provide structural support, insulation (myelin), and aid in repairing and maintaining neurons. Glia also regulate neurotransmitters and eliminate dead neurons, contributing significantly to the proper functioning of the nervous system.
The brain comprises intricate networks of neurons and glia, enabling communication and coordination among various brain regions. This interconnectedness facilitates bodily functions, emotions, thoughts, behavior, and other essential activities.
To validate this information, numerous reputable sources like MedlinePlus, the Society for Neuroscience, and the National Institute of Neurological Disorders and Stroke corroborate these fundamental concepts about the nervous system's structure, function, and cellular dynamics.
For further exploration, these sources provide a wealth of information on neurosciences, brain facts, and brain basics, aiding both enthusiasts and experts in understanding the complexities of this fascinating system.
