. Elements of human physiology. Physiology. 18 PHYSIOLOGY Thus the elements composmg a reflex arc are— (1) A sentient surface (such as the skin) connected by— (2) A sensory or afferent nerve (3) To a cell or group of cells, or of nerve-tracts in the central cerebro-spinal axis. This again is connected by— (4) A motor or efferent nerve to (5) A muscle or group of muscles. For muscle in (5) we may substitute gland-cell or any other cell in the body capable of responding by some change Fig. Diagram of reflex action, e. Sensory epithelium, Afferent nerve-fibre. Sensory cell.
. Elements of human physiology. Physiology. 18 PHYSIOLOGY Thus the elements composmg a reflex arc are— (1) A sentient surface (such as the skin) connected by— (2) A sensory or afferent nerve (3) To a cell or group of cells, or of nerve-tracts in the central cerebro-spinal axis. This again is connected by— (4) A motor or efferent nerve to (5) A muscle or group of muscles. For muscle in (5) we may substitute gland-cell or any other cell in the body capable of responding by some change Fig. Diagram of reflex action, e. Sensory epithelium, Afferent nerve-fibre. Sensory cell. Central nervous system. Branch of sensory cell in close contact with processes of , motor cell. Efferent nerve-fibre, terminating in end-plates on the muscle, m. in its condition to a stimulus reaching it from the central nervous system. To fire off a reflex arc, all that is necessary is an appro- priate stimulus applied to the sentient surface. Now we find that m all animals almost anj^ form of energy may serve as a stimulus. Thus it may be merely mechanical as when we poke the frog, or chemical, or electrical, or in the form of light, heat, or sound. In every case where a stimulus is applied there is an expenditure of some energy, though the amomit may be very slight—a conversion of one of those forms of motion (of masses or molecules) into some other. 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 Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
