Carry nerve impulses from the brain and spinal cord to muscles and glands.
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Neurons are cells that have been adapted to carry nerve impulses. A typical neuron has a cell body containing a nucleus, one or more branching filaments called dendrites which conduct nerve impulses towards the cell body and one long fibre, an axon, that carries the impulses away from it. Many axons have a sheath of fatty material called myelin surrounding them. This speeds up the rate at which the nerve impulses travel along the nerve (see diagram 14.1).  Diagram 14.1 - A motor neuron The cell body of neurons is usually located in the brain or spinal cord while the axon extends the whole distance to the organ that it supplies. The neuron carrying impulses from the spinal cord to the hind leg or tail of a horse, for example, can be several feet long. A nerve is a bundle of axons. A sensory neuron is a nerve cell that transmits impulses from a sense receptor such as those in the eye or ear to the brain or spinal cord. A motor neuron is a nerve cell that transmits impulses from the brain or spinal cord to a muscle or gland. A relay neuron connects sensory and motor neurons and is found in the brain or spinal cord (see diagrams 14.1 and 14.2). Diagram 14.2 - The relationship between sensory, relay and motor neurons Connections Between NeuronsThe connection between adjacent neurons is called a synapse. The two nerve cells do not actually touch here for there is a microscopic space between them. The electrical impulse in the neurone before the synapse stimulates the production of chemicals called neurotransmitters (such as acetylcholine), which are secreted into the gap. The neurotransmitter chemicals diffuse across the gap and when they contact the membrane of the next nerve cell they stimulate a new nervous impulse (see diagram 14.3). After the impulse has passed the chemical is destroyed and the synapse is ready to receive the next nerve impulse. Diagram 14.3 - A nerve and magnification of a synapse This page titled 14.3: The Neuron is shared under a CC BY-SA 3.0 license and was authored, remixed, and/or curated by Ruth Lawson via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request. If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. The nervous system includes the brain, spinal cord, and a complex network of nerves. This system sends messages back and forth between the brain and the body. The brain is what controls all the body's functions. The spinal cord runs from the brain down through the back. It contains threadlike nerves that branch out to every organ and body part. This network of nerves relays messages back and forth from the brain to different parts of the body. What Are the Parts of the Nervous System?The nervous system is made up of the central nervous system and the peripheral nervous system: How Does the Nervous System Work?The nervous system uses tiny cells called neurons (NEW-ronz) to send messages back and forth from the brain, through the spinal cord, to the nerves throughout the body. Billions of neurons work together to create a communication network. Different neurons have different jobs. For example, sensory neurons send information from the eyes, ears, nose, tongue, and skin to the brain. Motor neurons carry messages away from the brain to the rest of the body to allow muscles to move. These connections make up the way we think, learn, move, and feel. They control how our bodies work — regulating breathing, digestion, and the beating of our hearts. What carry impulses from the brain and spinal cord to muscles and glands?Motor nerves also known as efferent nerves, carry impulses away from the brain or spinal cord to muscles and glands. Sensory nerves also known as afferent nerves, carry impulses from sensory receptors towards the brain.
What is carried to the brain and spinal cord by nerves?Nerves are like cables that carry electrical impulses between your brain and the rest of your body. These impulses help you feel sensations and move your muscles.
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