PERIPHERAL NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM

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Peripheral Nervous System

Figure 1. Peripheral Nervous System (PNS) carries neural signals from the body to the Central Nervous System (CNS) and from the CNS out to the body.

The peripheral nervous system consists of nerves that carry signals from the senses (eyes, ears, skin, etc.) to the CNS and from the CNS to effectors (muscles and glands, which produce an observable effect). the drawing at the right, shows how it connects the body to the Central Nervous System (CNS = spinal cord in the vertebral column ["backbone"] and brain in the skull).

The peripheral nervous system is made up of nerves, which consist of bundles of axons (which are also called fibers). Axons are the part of the neuron (nerve cell) that is specialized for communication. They carry signals reliably over long distances (see Exercise Asgn2f).

Some nerves contain fibers that carry signals from the senses to the CNS. They are called sensory or afferent nerves, because they contain the axons of the sensory neurons. Other nerves contain fibers that carry signals from the CNS to the effectors (the muscles and some glands that have an effect). These are called motor or efferent nerves, because they contain the axons of the motor neurons, which activate muscles and glands. (To help you remember these names: afferent = carrying to [ad = to in Latin]; efferent = carrying from [ex = from or out in Latin]; motor = what makes you move.)