Because the autonomic nervous system regulates involuntary or automatic functions, it is called the involuntary nervous system. It is further subdivided into sympathetic and parasympathetic divisions. The autonomic nervous system, also called the visceral efferent nervous system, supplies motor impulses to cardiac muscle, to smooth muscle, and to glandular epithelium. Because these nerves permit conscious control of the skeletal muscles, it is sometimes called the voluntary nervous system. The somatic nervous system, also called the somatomotor or somatic efferent nervous system, supplies motor impulses to the skeletal muscles. ![]() Example 1: Identifying the Correct Process of a Reflex Arc. The efferent or motor division transmits impulses from the CNS out to the peripheral organs to cause an effect or action.įinally, the efferent or motor division is again subdivided into the somatic nervous system and the autonomic nervous system. An effector is the part of a body that carries out a response to a stimulus. The afferent or sensory division transmits impulses from peripheral organs to the CNS. The peripheral nervous system is further subdivided into an afferent (sensory) division and an efferent ( motor) division. Ganglia are collections, or small knots, of nerve cell bodies outside the CNS. Cranial nerves and spinal nerves extend from the CNS to peripheral organs such as muscles and glands. ![]() Nerves are bundles of nerve fibers, much like muscles are bundles of muscle fibers. The efferent nerves (also known as motor nerves) of the somatic nervous. The organs of the peripheral nervous system are the nerves and ganglia. The sympathetic system is distributed to effectors throughout the body, whereas parasympathetic distribution is much more limited. The effectors controlled by the somatic nervous system are the skeletal muscles. Although considered to be two separate organs, the brain and spinal cord are continuous at the foramen magnum. The brain is in the cranial vault, and the spinal cord is in the vertebral canal of the vertebral column. ![]() Because they are so vitally important, the brain and spinal cord, located in the dorsal body cavity, are encased in bone for protection. The brain and spinal cord are the organs of the central nervous system. The nervous system as a whole is divided into two subdivisions: the central nervous system ( CNS) and the peripheral nervous system ( PNS). PNS (Peripheral nervous system) Made of peripheral nerves which link the CNS to the bodys receptors and effectors. Each subdivision has structural and functional characteristics that distinguish it from the others. Although each subdivision of the system is also called a "nervous system," all of these smaller systems belong to the single, highly integrated nervous system. Acknowledgements Organization of the Nervous SystemĪlthough terminology seems to indicate otherwise, there is really only one nervous system in the body. A motor neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord.
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