301 Homework 2 Answer Key

301 Homework 2 Answer Key - BMD ENG 301 Homework 2 (counts...

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Unformatted text preview: BMD ENG 301 Homework 2 (counts for 4% of the final grade, due: 10/26/09) *************$*$*$$$$***$$**************************$*****$****$******** Negative marks will be given for incorrect answers on multiple-choice questions. ******************************************************$******$***$****** Molar gas constant (R) 8.3143 Jmol'lK'1 Faraday constant (F) 9.64870 X 104 Cmol'l 0°C 273.15 K 1. The term caudal means [1 point] (a) towards the back (b) towards the belly (c) towards the beak (or nose) fl (d) towards the tail 2. Sketch a surface View of the human cerebral hemispheres. Label the central sulcus, lateral fissure, pre— and postcentral gyms, and the four lobes. [8 points] 3. Suppose that you are recording a neuron’s resting membrane potential. You add enough KCl to increase the concentration in the external medium by 100 mM. Succinctly explain what you think would happen to the resting membrane potential and why? Also, succinctly, compare this to what you expect would happen if you had added enough NaCl to increase its external concentration by 100 mM instead. [6 points]. EEK would mom so a {hotel old/n: eel Poifinb‘al ‘ofld 60 would We tidbit/6 Hwde? onéNb‘otl vol/UNA ES q balance W SK and 5N0" \ ‘ t I make Esta mom meme. ThlS would Am :6] cold a 0130 kirk? stile WW (wile/Shell, 4. Make a simple sketch of the physical relationship that exists between the cerebellum, medulla, midbrain, pens and spinal cord. [3 points] omelet—>110 m 5. Suppose that you are recording action potentials from a neuron. How would the action potential be affected if you reduce the Na+ concentration in the external medium and why? What if you reduce the external K+ concentration instead? [6 points} A LNcflo er ammle web chNw Woman‘s“ w‘lu be Sma Qf 'e We WWGB/ mofifnfirl- barde .-T _ of A EK jg mgfiPfiQméi mike-fl POWQ 6. What are the states that can exist for the voltage-sensitive sodium conductance that is responsible for the action potential? Indicate the conditions under which the conductance can change from one state to another? [6 points] A 0 fl olr' x t “‘6 Clog—:0! 4i______,_ QlOSeol CH’ICKSHVCOEA) lflperpolcu'iSCen‘m Canal shin/L12.) 7. Make a rough sketch of a neuron with a myelinated axon and indicate where the myelin is. Indicate also a node of Ranvier and those points on the axon where action potentials are initiated and regenerated. Indicate the direction in which the action potential is propagated along the axon and explain why. What does myelin do for the axon and why is this a good thing? Finally note which glial cells are responsible for generating myelin in the central and peripheral nervous systems, telling me which is which. [10 points] SW 081“ W inkh‘cdbm site and is filial/08 Os were) 6 flmCleni/xesa din lfl‘sum arrow and odds (26;ka Pomqk lo ofiflkm' Oli canola,an CNS 3ng Mn “ 8. Name two fiber tracts that transmit neural information between the two hemispheres. [2 points] mien'or’ amWegoee posle‘n‘or (LG/m measure 2’ i J Cox-peg mllosomj “@YTMX 9. What is the name of the meninges closest to the brain surface? [1 point] P1 Ci mock/l" 10. Why does the delayed-rectifier potassium conductance reach a maximum and then decline during an action potential? [2 points] (S, [cm wlx'cm he 0 ‘ Kiwotmelswé flaw} Om if??? [05? when % Cicfefii'ifi ‘ Ktolmnela map“? l‘l (neaw‘wyfigb as {easy 11. Which of the following best characterizes the amplitude of an action potential? [1 point] —7 (a) BM - EK (b) ENa + BK 12. What is saltatory conduction? [1 point] r \ Prcfilxcm (DOWN Jumps W fl0d92% Rama“ ([0 {loom 13. The myelencephalon is another name for the [1 point] (a) thalamus (b) adult midbrain (c) pons (d) spinal cord (e) medulla (t) basal ganglia 17. Effector organs are [1 point for each correct answer] (a) sensory receptors ‘---> (b) muscles (c) motor nerve axons (d) ganglia fl (e) glands ( f) sensory nerve axons 18. Explain the difference between relative and absolute refractory periods. [2 points] AbSOiO‘iei [DQJiOOi r" canflél’ @0429; on oQSix'cm \ a we of i a“ i 3 i " Oi h“ m 0 M an wowvu’ Kit) W022) mOlifc-Sixémg \ 19. The following table lists the concentrations of major ions of the axoplasm and bathing medium of an axon held at 37°C. Axoplasm Extracellular medium mM mM [EC] 450 24 [Na+] 60 440 [C1'] 38 545 [Ca2+] 0.4 1 1 [May] 5 5 a. What is the potassium electrochemical equilibrium potential? [5 points] %_ $301413 “‘91? Nat/WSW PQW‘Q «~78 = 3 mV b. What is the chloride Nemst potential? [3 points] “’ll ‘1m\{ 0. If the membrane potential of the cell, as a result of an excitatory synaptic input, rises to a level of 0 mV, which ion is most close to being in equilibrium? [2 points] 9—’\’ ma 20. If the Nemst potential for sodium is +55 mV, can we say that the chemical energy of sodium is equal on the two sides of a nerve membrane when the electrical potential across that membrane is also +55 mV? If so, why? If not, why not? [3 points] N .Th Ne/miis‘f oiendfifl is om dammed OO‘lllWQ‘l’Di’l/t. I‘l’ {‘an 80m and Walled Om bo‘lR Si \S efiuod. 21. Provide a brief description of the channel opening and closing events that underlie N 0 the action [pagntial Explain the dependence upon time and voltage. [6 points]/K+ and woman N *woflfidg mmg’n‘vuta gong ahmnelS h‘ 0, 1 O a. Which of the following pharmacological agents blocks the voltage- sensitive sodium channel? [1 point] (a) Tetra-ethyl ammonium ion (TEA) % (b) Tetrodotoxin (TTX) 22. An afferent conducts nerve impulses [1 point] am) towards the CNS (b) outward from the CNS 23. Sketch the equivalent circuit for a patch of neuronal membrane with a resting potential, V... Identify the cytoplasmic and extracellular sides and label all circuit components. Assume that the membrane is permeable to Cl', K+ and Na+ and that there is a Na/K exchange pump, but that Cl' is distributed passively across the membrane. What is the relationship between Eel and Vr? [6 points] 24. Why does the ratio of gray matter to white matter tend to increase as one descends the spinal cord? [2 points] ' V‘ . - .n03i8 m We “that some 5’“ M M“ “W3 fie” C N 3 film as we, gPQflQL Coral ah one canals and S m P” tan t {00rd osmotic soNM’CLMSa _ were ad , M 0M SLPI‘nal 00 d 25. List the three brain regions that constitute the brainstem [3 points] midmm/ Pans medulla / 26. Which segments of the spinal cord innervate the trunk? [1 point] Thoracic 27. List four classes of glial cell. [4 points] Oli a DVD +8) mm :53 WC liCti" CE” ...
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This note was uploaded on 01/12/2011 for the course BME 301 taught by Professor Li during the Fall '10 term at Northwestern.

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301 Homework 2 Answer Key - BMD ENG 301 Homework 2 (counts...

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