Final answer:
A nerve composed of fibers that carry impulses to the brain or spinal cord from muscles or glands is called a sensory neuron or afferent neuron, which transmits sensory information to the central nervous system. Motor neurons or efferent neurons convey impulses from the CNS to muscles and glands.
Step-by-step explanation:
A nerve composed of fibers carrying impulses to the brain or spinal cord from muscles or glands is called a sensory neuron, also known as an afferent neuron. These neurons convert physical stimuli such as touch, light, and sound into electrical nerve impulses. The impulses then travel to the central nervous system. Conversely, motor neurons or efferent neurons carry nerve impulses away from the central nervous system to activate muscles and glands.
The nervous system is highly complex, with nerve cells, or neurons, being the primary functional units. Neurons transmit electrical signals, called nerve impulses, through their long fibers known as axons. These axons connect to other neurons at synapses, to muscles at neuromuscular junctions, or to glands, enabling communication throughout the body.
Nerves can be classified as cranial or spinal based on their connection to the brain or spinal cord. They are further distinguished by their function: sensory fibers bring information into the brain and target sensory nuclei, while motor fibers target and activate skeletal muscles.