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nerve

nerve
神经【名词】1. 【解剖学】神经; 2. 筋,腱;精力,气力; 3. 胆力,勇气;沉着,果断;大胆,胆量; 4. 神经过敏;胆怯,忧郁; 5. 主要部分,核心,中枢; 6. 【植物;植物学】脉,叶脉;【昆虫】翅脉; 7. 回缩性,(弹性)复原性

Definitions

a macroscopic cordlike structure of the body, comprising a collection of nerve fibers that convey impulses between a part of the central nervous system and some other body region. See Appendix 2-6 and see color plates.Depending on their function, nerves are known as sensory, motor, or mixed. Sensory nerves, sometimes called afferent nerves, carry information from the outside world, such as sensations of heat, cold, and pain, to the brain and spinal cord. Motor nerves, or efferent nerves, transmit impulses from the brain and spinal cord to the muscles. Mixed nerves are composed of both motor and sensory fibers, and transmit messages in both directions at once.Together, the nerves make up the peripheral nervous system, as distinguished from the central nervous system (brain and spinal cord). There are 12 pairs of cranial nerves, which carry messages to and from the brain. Spinal nerves arise from the spinal cord and pass out between the vertebrae; there are 31 pairs, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. The various nerve fibers and cells that make up the autonomic nervous system innervate the glands, heart, blood vessels, and involuntary muscles of the internal organs.Details of structure of components of nerve tissue. Details of structure of components of nerve tissue. Details of structure of components of nerve tissue. Details of structure of components of nerve tissue. accelerator n's the cardiac sympathetic nerves, which, when stimulated, accelerate the action of the heart.





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