動物生理学 III①Handout No. 13②
Figure 40-7 This viewof the horizontal semicircular canals fromabove shows how thepaired canals work
together to signal
head movement. Because of inertia, rotation of the head in acounterclockwise direction causes endolymph to move clockwise with respect tothe canals.This reflects the stereocilia inthe left canal in theexcitatory direction,
thereby exciting theafferent fibers on thisside. In the right canalthe hair cells are
hyperpolarized andafferent firing there
decreases.

③

Figure 22-2 The location and morphology of mechanoreceptors in hairy and hairless(glabrous) skin of the human hand. Receptors are located in the superficial skin, at thejunction of the dermis and epidermis, and more deeply in the dermis and subcutaneous
tissue. The receptors of the glabrous skin are Meissner's corpuscles, located in the dermal
papillae. Merkel disk receptors, located between the dermal papillae and bare nerveendings. The receptors of the hairy skin are hair receptors, Merkel's receptors (having aslightly different organization than their counterparts in the glabrous skin), and bare nerve
endings. Subcutaneous receptors, beneath both glabrous and hairy skin, include Pacinian
corpuscles and Ruffini endings. Nerve fibers that terminate in the superficial layers of theskin are branched at their distal terminals, innervating several nearby receptor organs; nerve
fibers in the subcutaneous layer innervate only a single receptor organ. The structure of thereceptor organ determines its physiological function.

④Figure 20-5 Different species rely on different parts of the body for adaptive somatosensory
information. These drawings show the relative importance of body regions in the somaticsensibilities of four species, based on studies of evoked potentials in the thalamus and cortex.

Figure 20-4 Somatic sensory and motor projections from and to the body surface and muscle arearranged in an orderly way in the cortex. The sensory map illustrated here is for Brodmann's area 1 in
the postcentral gyrus of the parietal cortex. Each area within the somatosensory cortex (areas 3a, 3b, 1,and 2) contains a full representation of the body (see Figure 20-5). Parts of the body that are important fortactile discrimination, such as the tip of the tongue, the fingers, and the hand, have disproportionately large
representations reflecting greater degrees of innervation. (Adapted from Penfield and Rasmussen 1950.)⑤
Figure 2 VR1 responds to purified
vanilloids and pepper extracts. a,Activation of VR1 by capsaicin andresinferatoxin. Left, agonists wereapplied sequentially to the same
Xenopus oocyte expressing VR1.
Membrane currents were recorded in
the whole-cell voltage-clamp
configuration. Bars denote duration ofagonist application. Right,
concentration-response curve forcapsaicin (filled squares) andresiniferatoxin (open circles).
Membrane currents were normalized ineach oocyte to a response obtainedwith 1 µM capsaicin and expressed asa percent of maximal response tocapsaicin. Each point represents meanvalues (±s.e.m.) from five independentoocytes. The Hill equation was used to
fit the response data. b, Antagonism bycapsazepine (cpz) and ruthenium red (RR). Current tracing at top left shows reversible block of capsaicin (cap; 0.6 µM) response by capsazepine (cpz; 10 µM) after 2 min
pretreatment. Slash marks represent washout periods of 2 and 3min, respectively (n = 3). A capsazepine inhibition curve is shown to the right fn = 4 independent oocytes foreach point). Current responses were normalized to that elicited by capsaicin alone in each oocyte. (0.6 µM, open diamond). Current tracing at bottom left shows reversible
block of a capsaicin (0.6 µM)-evoked response by ruthenium red (RR; 10 µM). Slash marks denote washout periods of 2 and 12 min, respectively (n = 3). c, Responses tocapsaicin (10 µM) and extracts derived from four varieties of peppers in oocytes expressing VR 1(30 s application). Bottom right, relative potencies of each pepper extract
are plotted (mean ± s.e.m., n = 3). Values were normalized in each cell to responses obtained with capsaicin (10 µM). Extracts evoked no responses in water-injected cells.
Reported pungencies for pepper varieties (in Scoville units) are: Habanero (H), 100,000-300,000; Thai green (T), 50,000-100,000; wax (W), 5,000-10,000; and Poblanoverde (P), 1,000-1,500 (ref. 23). Capsaicin (C) is rated as 16 x 106 units.