2007+Exam+2+with+key - Biology 222 Cover Page Exam 2,...

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Biology 222 Exam 2, Winter 2007 Name_______________________ Cover Page Put your name on every page! Every page missing your name will lose 1 point. Answer all 6 questions. Equations you may find helpful E RT zF Out in x = ln [ ] [ ] 0 o C = 273 o K At C E z out in z out in o x 20 25 2 58 10 = = . ln [ ] [ ] log [ ] [ ] At 37 0 C, the coefficient is 61.5 rather than 58 If temperature is not specified, you can assume it is a “warm” room temperature, and the coefficient of the Nernst equation is 60, rather than 58 or 61.5. At warm room temperature y x y y x x m g g E g E g V + + = * V g g E E g g m x y x y x y = + + * 1 i x =g x (V m -E x ) g= 1/R V=IR I= dQ/dt Q=charge in Coulombs m i g g = λ d g m 2 d g i V(x) = V 0 * exp (-x/ λ ) CV Velocity = x/t x=distance t=time 1) 20 points __________ 2) 20 points __________ 3) 15 points __________ 4) 10 points __________ 5) 20 points __________ 6) 15 points __________ Total __________ ] [ ] [ ] [ ] [ ] [ ] [ log * 60 10 out Cl in K in Na in Cl out K out Na m Cl P K P Na P Cl P K P Na P V + + + + = Prefix (label) Order of magnitude Milli (m) 10 -3 Micro (µ) 10 -6 Nano (n) 10 -9 Pico (p) 10 -12 Femto (f) 10 -15
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Biology 222 Exam 2, Winter 2007 Name_______________________ Cover Page
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Biology 222 Exam 2, Winter 2007 Name_______________________ Page 1 1. (20 pts) You decide to make surgical lesions in rats as a potential model to understand spinal cord injuries in humans. Prior to surgery you train rats to walk whenever you ring a bell. When you make no lesions to the nervous system during surgery, the animals still walk in response to the bell after waking up. a) (8 pts) Draw a sketch of a cross section though the lumbar spinal cord and adjacent dorsal root ganglion which illustrates the location of the cell bodies and axons of somatic motor neurons and sensory neurons, and the regions of the spinal cord devoted to white matter. Be sure to label your drawing to indicate dorsal and ventral. b) (2 pts) You remember that all efferent axons associated with the spinal cord run through ventral roots. What is an efferent axon? It carries information out of the CNS. c) (4 pts) You anesthetize an animal, and sever all ventral roots in the thoracic region on both sides of the spinal cord. When the animal awakens, it can still walk fine in response to the bell but has major defects in the function of its sympathetic nervous system Explain. The motor neurons that innervate the limbs are in the cervical and lumbar spinal cord, so all have intact axons, which is why walking is fine. Almost all the preganglionic neurons to the sympathetic nervous system exit in the ventral roots of the thoracic spinal cord so there would be almost no sympathetic responses. d) (4 pts) You anesthetize a second rat, and sever all dorsal roots on both sides of the animal along the
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2007+Exam+2+with+key - Biology 222 Cover Page Exam 2,...

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