![]() ![]() Of sodium and potassium ions inside and outside of the cellĭuring an action potential, the neuron goes through several steps:ġ. Normally the nerve cell is at resting potential, based on the concentration The nerve impulse is an electrical phenomenon that passes as a waveĪlong the surface membrane of a nerve fiber Multipolar neurons - cell body lies very close to dendrites characteristic.Unipolar neurons - cell body lies off to one side of axon characteristic.Bipolar neurons - cell body located near the middle of the axon.The types of neurons in the body include: Ganglia - groups of neuron cell bodies that lie peripheral to the.Telodendria (transmissive) - the terminal branches of an axon make.Axon (conductive) - a long cytoplasmic process also called the nerveįiber can transmit nerve impulses over a long distance (up to 1 m) withoutĭiminution of the amplitude of the signal.Dendrites (receptive) - form extensions into tissues that may synapse.Cell body (trophic) - contains the nucleus and metabolic machinery.Neurons are derived from ectoderm from the neural tube, neural crest the peripheral nervous system - the cranial and spinal nervesĪll parts of the nervous system are composed of a common cellular subunit.the central nervous system - the brain and spinal cord.The primary components of the nervous system are: It also acts as a messenger and coordination system for the body The nervous system determines responses of the body to changes in internal Because the autonomic nervous system regulates involuntary or automatic functions, it is called the involuntary nervous system.The nervous system is the most complex system of the body, yet it is ![]() 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. 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. 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 organs of the peripheral nervous system are the nerves and ganglia. 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). 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. ![]()
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