B100w09m1KEY

B100w09m1KEY - _AGB) with a single pulseat a point that is...

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BIPN 100, Mammalian Physiology I ANSWER KEY Winter, 2009 1 st Midterm Exam January 30, 2009 Page 1 _ 1. (10 points). For each of the following properties, write ( A ) if it describes an action potential, ( G ) for a graded potential, or ( B) for Both Action and Graded Potential. a. __G____ amplitude decreases with distance. b. __A____ always depolarizing c. __A____ all or none response to a stimulus d. __G____ temporal and spatial summation can occur e. __A____ propagates without loss f. __G____ the amplitude is always proportional to the stimulus intensity g. __G____ could be either depolarizing or hyperpolarizing h. __A____ information on stimulus intensity is in the frequency of the response i. __A____ has refractory periods j. __G____ occurs primarily in the dendrites and cell body 2. (12 points). Two years ago the Supreme Court stayed an execution by lethal injection and agreed to consider whether such a method is unconstitutional because it involves cruel and unusual punishment. The execution consists of the sequential intravenous injection of three substances that have the effects listed below. Indicate: 1. The mechanism of each of the observed effects including the neurotransmitter (if any) involved. 2. The type of ion channel(s) opened or blocked, and 3. The change in membrane potential (hyperpolarization, depolarization or no change) of the affected cells. A. Puts the person to sleep: A drug that increases opening of GABA A receptors which are Cl¯ channels. That will hyperpolarize brain cells and inhibit them, inducing sleep. B. Paralyzes his muscles: A drug that blocks acetylcholine binding to the nicotinic Ach receptors in muscles, preventing synaptic transmission at the neuromuscular junction. There is no channel opening upon the action potential in the axon, even if there is Ach release, paralyzing the muscle. C. Stops his heart: Concentrated KCl which will increase the extracellular K concentration depolarizing the muscle, causing Na and K channels to open, but the membrane potential cannot repolarize because of the high external K and no more action potentials in the heart muscle can occur, stopping the heart because the Na channels remain inactivated and K channels remain open. 3. (12 points). In an experiment you stimulate
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This note was uploaded on 03/21/2009 for the course BIPN 100 taught by Professor French during the Spring '07 term at UCSD.

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B100w09m1KEY - _AGB) with a single pulseat a point that is...

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