. Animal biology; Human biology. Parts II & III of First course in biology. Biology. The Work of the Spinal -There are two functions of the cord : reflex action and transmission of impulses from the body to the brain. Reflex action is action that takes place without the aid of the will. Reflex action never begins in the cord, but at the outer end of a sensory fiber, usu- ally located in the skin. The impression goes to the cord along a sensory fiber. It is received in a sensory cell and transferred by den- drons to a motor cell which sends back an impulse along a motor fiber to a mu
. Animal biology; Human biology. Parts II & III of First course in biology. Biology. The Work of the Spinal -There are two functions of the cord : reflex action and transmission of impulses from the body to the brain. Reflex action is action that takes place without the aid of the will. Reflex action never begins in the cord, but at the outer end of a sensory fiber, usu- ally located in the skin. The impression goes to the cord along a sensory fiber. It is received in a sensory cell and transferred by den- drons to a motor cell which sends back an impulse along a motor fiber to a muscle; the muscle contracts and the action is complete. At least two nerve cells are necessary for reflex action. The actions of the lowest animals are almost entirely reflex. ..,.. *.""'*> ••?*=.•• • * • ;. v. .- • • * .,• .. • ^0:1, . ..,•_- ••.-- ..-•••,••. .:>.:»; FIG. 108. —SECTION OF SPINAL CORD, showing nerve cells (large black spots) with their branches (black dots and lines). Five bundles of nerve fibers are shown near upper margin. (Peabody.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan Co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1910
