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Exam+2+--+Spring+2004+_Practice_+--+ANSWERS

Exam+2+--+Spring+2004+_Practice_+--+ANSWERS - T B IO225S...

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BIO225 Spring Term2004 Practice Exam II key , ,1 ,, "i , BIO225 Sprine Term 2004 '\ Practice Exam II Key Q1. Name the characteristics of neuron strlrcture and function that play crucial role in unidirectional and rapid transmission of electrical signal (Action Potential). Presence of Myelin sheath makesinternodes and Nodes of Ranvier; in inernodes there are no ion channels and no extracellular fluid. Ion channels and extracellual fluid available only at Nodes of Ranvier, which allows saltatory propagation of AP - rapid transmission. Occurance of Refractory phase after AP allows undirectional movement of AP - towards the tip of the axon. Q2. Describe the unique characteristics of Action Potential. Threshold stimulus. All or none. Propagation w/o decrement. Refractory phase. Q3. Match the function with correct structtne. a. Dendrite (2) L lnitiation AP b. Axon (6) 2. Reception of information c. Axon Hillock (1) 3. Intracellular trafficking d. Internode (5) 4. Chemical propagation of AP e. Synapse (4) 5. Facilitates saltatory propagation of AP f. Cytoskeleton (microtubules) (3) 6. Electrical propagation of AP Q4. Dendritespines, a, are the site of signal reception b. release neurotransmitters c. are the site of transcription for protein synthesis d. aandc e. none ofthe above Q5. An Action Potential that travels down the lengthof axon originates in the a. axon b. dendrite ending(tip) c. dendrite base d. Axon hillock e. Cell body
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BIO225 Spring Term 2004 Practice Exam II key Q6. Blood brain barrier is formed by a. astrocytes b. oligodendrocytes Q7. Myelin sheath of the Central NervousSystem (CNS) is formed by Q8. Based on the knowledge gained in lectures, describe what physiological function will be affected by deficiency of each of the following in our diet, a. Iodine - thyroid hormone function (I is essential for synthesis of T3/T4) b. Nat - Neural and muscle function (seneration AP depends upon Na* channels and Na* concentration Na channels also function in vision - it is the inhibition of Na channels that is responsible for a hyperpolarization inhibiting the release of glutamate to lift inhibition of signaling from bipoloar cells) c. Kr - Neural and muscle function (refractorv phase depends upon K+ channels and K+ concentration)...hearing depends on K influx that causes a depolarization in a unique situation (b/c endolymph is more highly concentrated in K than the intracellular hair cellsenvironment) d. Ca*+ - Neurotransmitter release at synapse and muscle contraction.
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