PHYSCI 107 Chapter Notes - Chapter 9: Retina, Aortic Body, Internal Carotid Artery
12 Nov 2020
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Document Summary
Sensory receptors are specialized cells or cell processes (extensions) that monitor conditions inside or outside the body. The simplest receptors are the dendrites (processes) of sensory neurons. The branching tips of these dendrites are called free nerve endings. Free nerve endings extend through a tissue the way grass roots extend into the soil. They are sensitive to many types of stimuli. For example, a touch receptor is very sensitive to pressure but insensitive to chemical stimuli. A taste receptor is sensitive to dissolved chemicals but insensitive to pressure. The most complex receptors, such as the visual receptors of the eye, are protected by accessory cells and layers of connective tissue. The larger the receptive field, the poorer is your ability to localize a stimulus. A touch receptor on the general body surface, for example, may have a receptive field of 7 cm (2. 75 in. ) in diameter.
