BOOK REPORT 1

INTRODUCTION TO THE NERVOUS SYSTEM.

the nervous system is communication system based on the conduction of impulses that provide information and give directions. structures called receptors are sensitive to certain changes in their immediate environment. receptors in the skin, for example, generate impulse when stimulated by touch or pressure.receptors are located on the ends of nerve fiber, which transmit the impulse to the spinal cord or brain to effectors such as skeletal ,smooth, and cardiac muscle, and glands, which cay out the direction sent from the spinal cord or brain. still other nerve fibers transmit information to other nerve fiber.

the operation of the nervous system involves receiving and processing information generated by many receptors in many parts to the body, and directing the response of many effectors to bring about appropriate response.



the nervous system can be and has been divided into many different fragments, each one of which is often refereed to as a"nervous system." there is, however, only one nervous system, though it does have several parts. structurally, the nervous system may be divided into the central nervous system and the peripheral nervous system. the central nervous system consists of the Brian and the spinal cord. it contains the centers where connection are made between nerve fibers bringing information from receptors and nerve fibers carrying in formation to effectors.the brain , which is the highly specialized superior end of the spinal cord it is capable of the sophisticated activities including consciousness, which in turn is necessary for perception and awareness, willed movements and complex movement patterns, learning, and memory. the brain exerts control over many spinal cord activities and even over certain endocrine glands.

the peripheral nervous system is made up of the nerves connecting the peripheral parts of the body with the central nervous system. twelve pairs of nerves arise from the brain and are called the cranial nerves. thirty-one pairs of spinal nerves arise from the spinal cord. there are eight cervical, twelve thoracic.five lumbar, five sacral and one coccygeal nerve, named on the basis of the level at which they emerge from the vertebral canal. the somatic component is what is usually meant by "the nervous system," since it innervates supplies the general body structures(soma= body).



CELL OF THE NERVOUS SYSTEM.

what is commonly known as a "nerve," such as one might find in an extremity, is made up of many nerve cell processes held together by connective tissue in much the same way that muscle cells are held together. the outermost layer is the epineurium, which ensheaths the whole nerve and is continuous with the deep fascia. group of nerve fiber are surrounded by perineurum, and individual nerve fiber are enclosed by endoneurium. small blood vessels also run in the connective tissue. as large nerve trunks approach the periphery they divide into progressively smaller branches, until finally only a single fiber remains.