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BIO 410 EXAM I VERSION A Oct 6, 1988 There are no lists of answers to these questions. Figure them out for yourself. If necessary, you can ask about them at the review session scheduled before each exam. Short answer section. 1.-2. List four mechanisms by which substances can cross the cell membrane. 3. Which mechanisms above are saturable--are limited to a finite maximum rate even if concentration gradients are increased? 4. Why can't the heart muscle be tetanized? 5. What is meant by the 'crossed response' in the withdrawal reflex and why is it functionally adaptive? 6. What is the partition coeficient and how is it related to the ability of things to cross the cell membrane. 7.-10. Give the function of the following intracellular organelles. golgi apparatus vesicle rough endoplasmic reticulum lysosomes 11.-13. What are the three components that make up a homeostatic mechanism. Choose something that is highly regulated in the body and tell which organ of the body might perform each role . 14. What is a motor unit? 15.-16. Name two lines of evidence for chemical transmission at the neuromuscular junction? for vesicular release? 17-18. What are the two effects of myelination of the axon? 19. Name one way that we can differentiate between channels and carriers in the plasma membrane. 20-22. Fill in the blanks below to give the differences between the 3 muscle types. Duration Levels of Levels of Krebs Cycle of twitch Myoglobin Glycolysis Enzymes Use of muscle. (long/short) (high/low) (high/low) (high/low) Fast,fatiguable ----------- -------------- ---------- ------------- ------------- Fast,resistant ----------- ------------ ---------- ------------- ------------- to fatigue Slow ----------- ------------- ----------- ------------ ------------------ 23-25. Fill in the blanks below to give the differences between electrotonic potentials and action potentials (yes or no).

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Change in Refractory Propagated Summates Graded Memb. Perm. Period Electrotonic Potl-------- -------- ------ --------- ------- Action Potential-------- -------- ------ --------- ------- 26. What happens to nerve fibers in Multiple Sclerosis and why does this cause loss of function. 27. Organ systems are made up of organs. Organs are made up of_______________, which are in turn made up of cells whose function is based on ______________________. Give also some examples of types of cells and their organization into the next higher level. 28. Name four difference between action potentials and receptor/synaptic potentials. 29. Repolarization after the peak of the action potential is due to what two factors? 30. What factors determine the conduction velocity in a nerve fiber. 31. Name and explain the two different type of synaptic potential summation. MULTIPLE CHOICE SECTION. INTRODUCTION/HOMEOSTASIS/TISSUE ORGANIZATION 1. Match the intracellular organelle with its function: vesicle a) synthesis of proteins for membranes and secretion. golgi apparatus b) contains materials engulfed or to be secreted. mitochondria c) produces ATP via krebs cycle/oxid. phosphorylation. lysosomes d) processes proteins to be secreted. rough ER e) contains degradative enzymes for engulfed particles. 2. The measured permeability of the cell membrane to urea is a) less than what would be expected from its diffusion constant in water. b) about what would be expected from its diffusion constant in water. c) somewhat greater than many other small molecules because of its solubility in oil as well as in water d) a) and c) e) b) and c) 3. Osmosis: a) occurs without any difference in water concentration across the membrane. b) is relevant to plant physiology but not to animal physiology. c) is the net movement of water because of its concentration gradient across the membrane. d) all the above. e) a) and c) only are true. 4. Water is important to living organisms because:

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a) its high heat capacity and high thermal conductivity make it good insulation. b) its high heat capacity takes up or buffers some of the heat generated by the body, especially active muscles. c) its high heat of evaporation cools the body during sweating. d) all the above. e) b) and c) only. 5. The rate that an uncharged molecule diffuses across a cell membrane is a function of: a) its concentration gradient b) the voltage across the membrane c) the activity of the Na+ pump d) its permeability e) both a) and d) are correct 6. In the absence of specific transport pathways, membranes would be permeable to: a) sugars b) ions c) lipids d) amino acids e) none of the above 7. Movement of water across membranes: a) depends on the concentration gradient for water. b) is termed osmosis c) depends on the total concentration of solutes on each side. d) can only occur by pinocytosis. e) a), b) and c) are correct. 8. The movement of a substance in a direction opposite to its concentration gradient could be the result of: a) cotransport with Na+ b) passive diffusion c) facilitated (carrier mediated) diffusion d) active transport utilizing ATP e) both a) and d) are correct 9. Examples of connective tissues are: a) the lining of the intestines. b) the skin. c) bones d) the blood. e) both c) and d) 10. Diffusion rates (moles per second moving across an area) depend upon: a) the concentration gradient. b) the temperature c) the cross sectional area. d) all the above e) a) and c) only 11. The interstitial fluid is located a) within cells b) outside the body c) in hollow organs d) between cells e) a) and b) are correct. 12. Bone is what type of tissue? a) nervous b) epithelial c) endothelial d) connective e) secretory. 13. A mechanism which returns a body function to normal (set point) is an example of: a) negative feedback. b) a homeostatic mechanism c) a Positive feedback mechanism d) a) and b) only e) b) and c) only 14. The difference in electrical charge between two points generates a driving force for electrical current called electrical potential, which is measured in a) amps b) volts c) resistance, ohms d) conductance e) permeability.

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15. Lipids a) are water soluble b) are present in cell membranes c) may be amphipathic d) include steroids e) b), c) and d) are correct 16. The sequence of amino acids making up a protein is termed its a) primary structure b) secondary structure c) tertiary structure d) quaternary structure e) none of the above. 17. Enzymes a) are starches b) act as catalysts c) reduce activation energies d) may act on more than one substrate e) all the above except a) are true 18. A situation in which an increased amount of substrate does not increase the reaction rate is called a) enzyme competition b) enzyme saturation c) substrate affinity d) allosteric effect e) none of these 19. The primary stored form of carbohydrates in humans is a) adipose tissue b) glucose c) maltose d) steroids e) glycogen 20. The partition coefficient of a substance a) is the ratio of the concentrations of a substance inside and outside the cell b) is proportional to the solubility of the substance in oil c) determines the ability of the substance to diffuse through the lipid bilayer d) a) and c) are true e) b) and c) are true 21. Which of the following are true? a) Maintenance of homeostasis requires specialization of cells. b) The benefits of homeostasis include optimization of performance and survival in harsh environments. c) Each organ is made up of tissues of only one type d) all the above are true e) a) and b) only 22. The diffusion coefficient a) varies with temperature b) is different for different molecules c) is empirically derived by measuring rate of diffusion flux per unit area and unit concentration difference d) all the above e) a) and c) only 23. Diffusion across lipid bilayers a) is always slower than across the same distance in solution b) depends upon the partition coefficient c) doesn't occur for water d) all the above e) a) and b) only

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24.The three parts of a homeostatic control mechanism include a) the effector b) the sensor c) the cerebral cortex d) a) and b) e) a) and c) 25. Which of the following are true? a) proteins and glycogen do not cross the membrane b) gases like urea, O2 and CO2 diffuse through the lipid bilayer c) ions cross the membrane via channels, primary and secondary active transport d) all the above a) and b) only 26. The ion channel shows selectivity for ions by a) lining the pore with charges (negative or positive) b) the pore diameter matches the diameter of the naked (unhydrated) ion c) the pore diameter matches the diameter of the hydrated ion d) a) and b) e) a) and c) 27. Those mechanisms of crossing the cell membrane that are generally saturable include: a) carriers b) active transport c) ion channels d) all the above e) a) and b) only 28. Which are true of active transport? a) Only primary active transport can accumulate concentration inside higher than outside b) Only primary active transport uses energy c) only primary active transport uses ATP d) all the above e) a) and c) 29. Which are true of membrane transport mechanisms? a) examples of primary active transport are Na+/K+ pump and the Ca++ pump b) most cells' glucose transporters are passive carriers (facilitated diffusion) c) glucose transporters in kidney and sm. intest. are secondary active transport d) all the above e) a) and c) 30. Which of the following are true a) glucose is always actively transported into cells b) gasses such as O2 and CO2 typically diffuse through the lipid bilayer c) ions can go through specific channels, or be transported via primary or secondary transporters d) all the above e) c) and b) only 31. Cells regulate to changing demands by a) synthesizing and inserting new proteins into the membrane b) altering existing channels, carriers and transporters, typically by phosphorylation c) altering the amino acid sequence of proteins already in the membrane d) all the above e) a) and b) only

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32. A membrane potential requires a) different concentrations of sodium ions on the two sides b) active transporters for Na/K c) permeability to an ion with different concentration on the two sides d) all the above e) a) and c) only 33. The levels of organization between the body and its individual cells are: a) the organ systems and the tissues b) the organs and molecules c) organs and tissues d) the organ systems, organs and tissues e) the organs, tissues and molecules 34. The factors that make the diffusional flux of molecules go faster are a) a bigger size of molecule b) a higher temperature c) a larger cross sectional area d) all the above c) b) and c) only 35. Transport mechanisms that can accumulate a substance above its extracellular concentration include: a) facilitated diffusion b) primary active transport c) secondary active transport d) all the above e) b) and c) only 36. Ions typically move across membranes by a) facilitated diffusion b) channels c) active transport d) all the above e) b) and c) 37. Glucose is transported across the membrane by a) channels b) facilitated diffusion c) secondary active transport d) all the above e) b) and c) only 38. The view of life that attempts to describe all life phenomena in terms of physical and chemical laws is a) mechanistic b) vitalist c) homeostatic d) teleological e) a) and d) 39. The aggregation of differentiated cells with similar properties results in the formation of a) organs b) organ systems c) tissues d)structural units e) molecular assemblies 40. Which one of the following is not one of the three classes of muscle tissue a) cardiac b) epithelial c) skeletal d) smooth 41. The fast conduction of information from one part of the body to another is the role of a) muscle cells b) basement membranes c) ground substance d) neurons e) blood vessels 42. The internal environment surrounding each cell is a) maintained at exactly the same level at all times b) extremely variable

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c) controlled within a narrow range of changes d) not controlled at all e) none of the above 43. Virtually every cell in the body must be able to do all of the following except a) extract energy from nutrients b) move materials across its membrane c) make hormones d) synthesize proteins e) synthesize RNA 44. If 2/3 of the total body water is intracellular, and there are 14 liters of extracellular fluid, and 80% of the extracellular fluid is interstitial, the the amount of interstitial fluid in the body is approximately a) 11 liters b) 42 liters c) 3 liters d) 14 liters e) 22 liters 45. If the molecular weight of NaCl is 58, then which of the following is true? a) there are 58 moles in one gram of NaCl b) one mole of NaCl weighs 58 grams c) there are approximately three times as many molecules in one mole of glucose (molecular weight of 180) as in one mole of NaCl d) all the above e) a) and c) 46. The subunits of proteins are called a) nucleic acids b) fatty acids c) amino acids d) unsaturated fatty acids e) RNA 47. A solution with a pH of 9 is a) acidic b) neutral c) basic d) logarithmic e) none of the above 48. A gene is composed of a) ribosomes b) nucleic acids c) amino acids d) fatty acids e) carbohydrates 49. The major function of the plasma membrane is a) to make the cell impermeable to water b) to provide genetic information c) to provide chemicals for metabolism d) to regulate the passage of molecules into and out of the cell e) a) and d) 50. If oxygen is not present in muscle, the end product of glycollysis is a) pyruvate b) lactic acid c) acetyl coenzyme A d) carbon dioxide and water e) none of the above 51. Diffusion a. depends upon the random motion of molecules b. results in net movement of molecules from regions of low concentration to regions of high concentration c. is important for moving things over large distances in the body d. both a) and b) are true e. both b) and c) are true 52. Which of the following statements regarding the diffusion of nonpolar solutes across the cell membrane is correct? a) at equilibrium for solute X, the flux of X across the cell membrane is zero

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b) at equilibrium for solute X, the net flux of X across the cell membrane is zero c) at equilibrium for solute X, the concentration of X inside the cell is equal to the concentration outside. d) both a) and c) e) both b) and c) 53. Carrier mediated transport a) involves a specific membrane protein that functions as a carrier molecule b) always involves the movement of substances against a concentration gradient c) always requires the direct expenditure of energy d) all the above a) and b) only 54. Which of the following are true about primary and secondary active transport? a) Primary active transport uses energy directly derived from ATP whereas the secondary active transport does not. b) Primary active transport uses a carrier that is an ATPase whereas secondary AT does not. c) Primary active transport uses a carrier whose binding affinity for the solute is modified by covalent modulation

whereas secondary AT does not. d) All the above e) a) and c) only 55. Glucose a) enters most cells by facilitated diffusion b) enters most cells by secondary active transport c) concentrations inside most cells are generally the same as those in the extracellular fluid. d) b) and c) e) None of the above. 56. Which of the following is a feature that distinguishes active transport from facilitated diffusion? a) saturability b) requirement for a carrier molecule c) specificity d) presence of a transport maximum e) requirement for metabolic energy 57. If the ATP-generating mechanisms in a cell are poisoned and the cell has depleted its energy reserves, a) primary active transport would cease immediately b) secondary active transport would cease immediately c) eventually there would be no potential difference across the membrane d) both a) and b) e) both a) and c) 58. If a cell is placed in a hypotonic solution, it a) will swell b) will shrink c) will stay the same size d) may swell, shrink or stay the same size depending on the concentration of penetrating and nonpenetrating solutes in

the solution. e) none of the above. 59. If pure water and an aqueous solution of nonpenetrating solute are separated by a membrane permeable to water a) water will diffuse by osmosis until the water concentrations on the two sides are equal b) both water and the solute will diffuse across the membrane down their concentration gradients until a state of

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equilibrium is established c) water will diffuse by osmosis until stopped by opposing hydrostatic pressure. d) No movement will occur between the two sides e) None of the above. 60. An example of a hypertonic solution is a) 400mM NaCl b) 300mM glucose c) 100mMMgCl2 d) 300mM urea e) none of the above 61. Which of the following solutions is not isotonic? a) 300mM glucose b) 300mM sucrose c) 100mM MgCl2 d) 300mOsm NaCl e) 200mM MgSO4 62. The concept of homeostasis a) includes the concept of an error signal b) refers to maintaining the dynamic constancy of the internal environment c) refers only to the regulation of body temperature d) a) and b) e) b) and c) 63. Which of the following is the correct sequence of a regulatory reflex arc? a) stimulus, effector, efferent pathway, integrating center, afferent pathway, receptor b) stimulus, receptor, efferent pathway, integrating center, afferent pathway, effector c) stimulus, receptor, afferent pathway, integrating center, efferent pathway, effector d) stimulus, effector, afferent pathway, integrating center, afferent pathway, receptor e) effector, efferent pathway, integrating center, afferent pathway, receptor, stimulus MEMBRANE POTENTIAL/ACTION POTENTIAL 1. In frog muscle with ion concentrations approximately as given, which of the following are true?

Sarcoplasm (inside) Extracell.Fluid (outside) K+ 120mM 2.8mM Na+ 20mM 120mM Cl- 3mM 125mM

a) the [Cl-] inside is about what would be expected for a Donnan system. b) The membrane potential is inside positive, due largely to [Na+]. c) there must be another anion present inside in high concentration. d) all the above are true. e) a) and c) only. 2. In the system at right: 10M 100mM (at equilibrium) KBr KBr side 1 side 2 a) if the membrane is permeable to Br- only, side 1 is neg. relative to side 2.

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b) if the membrane is permeable to K+ only, side 1 is neg. relative to side 1. c) if the membrane is permeable to Br- only, side 2 is neg. relative to side 1. d) if the membrane is perm. to both K+ and Br-, then both will move and make side 1 neg relative to side 2. e) none of the above is true. 3. In the system above, the magnitude of the potential generated if the membrane is permeable only to one ion will be (regardless of sign): a) 116V b) 58mV c) 58V d) 116mV e) 116uV 2a. In the system at right: 1mM 100mM

(at equilibrium) RbBr RbBr side 1 side 2

a) if the membrane is permeable to Br- only, side 2 is neg. relative to side 1. b) if the membrane is permeable to Rb+ only, side 1 is neg. relative to side 2. c) if the membrane is permeable to Br- only, side 1 is neg. relative to side 2. d) if the membrane is perm. to both Rb+ and Br-, then both will move and make side 1 neg.relative to side 2. e) none of the above is true. 3a. In the system above the magnitude of the potential generated if the membrane is permeable only to one ion will be (regardless of sign): a) 116V b) 58mV c) 58V d) 116mV e) 116uV 4. In the Donnan system to the right: 228mM K+ 172mM K+

(memb. perm. to K+, Cl- and H20) 128mM Cl- 172mM Cl- 100mM A- side 1 side 2

a) substance A- will move from side 1 to side 2. b) there is no osmotic imbalance. c) side 1 is neg. with respect to side 2, because its Cl- conc. is lower. d) side 2 is neg. with respect to side 1 because it has a lower K+ conc. e) more Cl- and K+ will move from side 2 to side 1. 4b. In the Donnan system to the right: 229mM Na+ 171mM Na+

(memb. perm. to Na+, F- and H20) 129mM F- 171mM F- 100mM A- side 1 side 2

a) side 2 is neg. with respect to side 1 because it has a lower Na+ conc. b) substance A- will move from side 1 to side 2. c) side 1 is neg. with respect to side 2, because its F- conc. is lower. d) there is no osmotic imbalance.

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e) substantially more F- and Na+ will move from side 2 to side 1. 5. Myelination of the axon: a) consists of several extra membrane layers produced by glial or Schwann cells. b) generates the energy required to maintain the ionic gradients used in the AP. c) increases conduction velocity, making it proportional to axon diameter instead of to the square root of diameter. d) all the above are true. e) a) and c) only are true. 6. If the membrane's sodium-potassium pump is suddenly blocked by ouabain, then a) the nerve cell can fire only one more action potential. b) the nerve cell can still fire action potentials for many minutes. c) Na+ and Cl- accumulate inside the nerve, which swells osmotically. d) a) and c) are true. e) b) and c) are true. 7. During the action potential: a) the membrane is refractory to another stimulus. b) the inside Na+ concentration rises dramatically. c) the Na+/K+ pump shuts off temporarily. d) both the Na+ and K+ concentration gradients reverse. e) a) and c) only. 8. When the membrane potential of a nerve or muscle is depolarized from the resting level to threshold: a) the permeability of the membrane to K+ is suddenly decreased. b) the permeability increase for Na+ precedes that for K+. c) the permeability to Na+ and K+ are increased simultaneously. d) the sodium pump shuts down suddenly. e) none of the above are true. 9. An equilibrium potential for an ion is defined as... a) a diffusion potential, the magnitude of which is predicted by the Nernst Equation for that ion. b) the potential across a membrane that is permeable to that ion when the concentrations of that ion are equal on the two sides of the membrane. c) the membrane potential at which the electric work to move one ion is equal in magnitude but opposite in direction to the concentration gradient-generated work. d) a) and c) are true. e) b) and c) are true. 10. In the system diagrammed at right 10mM KCl ?mMKCl KCl is the only solute in the solutions Side 1 Side 2 on the two sides, a membrane potential H2O-----------------> +58mV of 58mV is measured with Side 2 positive, and water moves across as shown. Which of the following could be true? a) Side 2 has 100mM KCl and the membrane is permeable to K+. b) Side 2 has 1mM KCl and the membrane is permeable to Cl-. c) Side 2 has 100mM KCl and the membrane is permeable to Cl-.

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d) Side 2 has 1mM KCl and the membrane is permeable to K+. e) either c) or d) could be true. 11. If the following two compartments containing: the ions listed are separated by a membrane whose 100mM KCl 100mM NaCl permeability to Na+ is 10X greater than its 10mM NaCl 10mM KCl permeability to K+, then side 1 will initially be: Side 1 Side 2 a) positive b) not charged c) negative d) cannot be determined.

12. In the above diagram if the membrane is permeable only to Cl-, side 1 will be: a) negative b) positive c) not charged d) cannot be determined 13. In the normal nerve action potential, which of the following is true? a) the K+ permeability increases more than the Na+ permeability in the rising phase. b) Ca++ permeability increases more than Na+ permeability. c) approaching the peak the Na+ permeability is more than the K+ permeability. d) the Na+ permeabilty increases before the K+ permeability. e) both c) and d) are true. 14. During the relative refractory period of an action potential: a) the membrane is always positive inside. b) some Na+ channels are still inactivated. c) the K+ permeability is higher than in the resting state. d) b) and c) are correct e) a), b) and c) are correct. 15. The nerve fiber has a resting potential of -70mV. During the repolarization phase of the action potential the voltage becomes more negative, reaching a value of -85mV before recovering to the resting level. The amount of this afterhyperpolarization would be most strongly affected by small increments in the concentration of: a) external Na+ b) internal K+ c) internal Na+ d) external K+ e) none of the above affect it. 16. The portion of a nerve cell that: a) conducts action potentials is called the dendrite. b) receives synaptic contacts is called the axon. c) releases synaptic transmitter is called the presynaptic terminal. d) all the above. e) none of the above. 17. The repolarization of the membrane after an action potential (falling phase) is due to: a) the turning on of the Na/K pump. b) the opening of K+ channels. c) the spontaneous closing of the Na+ channels. d) all the above. e) b) and c) only.

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18. In the system diagrammed side 1 side 2 side 3 at the right (analogous to 10mM 100mM 10mM the potential across an KCl KCl KCl epithelial sheet), with both membranes permeable to K+: a) the potential of compartment 1 with respect to compartment 3 will be 0mV. b) the potential of compartment 2 with respect to compartment 3 will be -58mV. c) the potential of compartment 1 with respect to compartment 3 will be -116mV. d) both a) and b) are correct. e) both b) and c) are correct. 19. Ions cross the plasma membrane a) by going through channels in the hydrated state. b) via cotransport carriers and active transporters. c) by going through channels after stripping off hydrating water molecules. d) b) and c) only. e) a) and b) only. 20. If ENa+ = +60mV and EK+ = -80mV, then the potential across a membrane permeable only to Na+ would most likely be a) +60mV b)+30mV c) -10mV d) -30mV e) -80mV 21. During the absolute refractory period a) action potentials can occur but have a high threshold b) action potentials cannot occur c) most Na+ channels are inactivated d) a) and c) are correct e) b) and c) are correct. 22. Repolarization after the AP is due to a) the spontaneous inactivation of the Na+ Channels b) the turning on of the Na+/K+ pump c) the delayed activation of more K+ channels d) all the above e) a) and c) are true 23. The conduction velocity a) is proportional to the square root of the diameter for myelinated axons b) is proportional to the diameter for unmyelinated axons c) is faster if the axon is myelinated d) all the above e) b) and c) only 24. Electrotonic potentials a) have shorter refractory periods than APs b) are not capable of summation c) are not propagated but spread passively d) are all one size e) all the above 25. Electrotonic signals a) are not natural but occur only when the neuron is electrically stimulated

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b) are not due to opening of voltage dependent ion channels c) occur naturally as EPSPs and sensory receptor potentials d) a) and b) are true e) b) and c) are true 26. Which of the following are true? a) All vertebrate axons are myelinated b) APs are an example of digital signalling c) all myelinated axons conduct faster than all unmyelinated axons d) all the above are true e) a) and b) are true 27. Multiple sclerosis a) is due to loss of Na+ channels at nodes of Ranvier b) is an autoimmune disease c) is due to removal of myelin from axons d) all of the above e) b) and c) 28. Na+ channels differ from K+ channels in that a) they turn off again with continued depolarization b) they open up faster upon depolarization c) they are almost all closed at rest d) all the above e) a) and b) are true 29. The refractory period a) is only during the AP itself b) is due to inactivation of Na+ channels c) is due to increased K+ permeability d) all the above e) b) and c) only 30. Which of the following are true? a) Only excitable cells have Na+/K+ pumps to maintain a Na+ gradient b) No action potentials can be fired after the pump is blocked c) Cl- contributes to the resting potential d) all the above e) a) and c) are true 31. Some properties of the action potential are a) a threshold level of depolarization for triggering b) a fixed size of APs c) a refractory period during and after an AP for triggering another AP d) all the above e) a) and c) only 32. Evidence that the rising phase of the action potential is due to Na+ entry is a) experiments with replacement of outside Na+ show smaller or no APs b) voltage clamp experiments show that Na+ channels activate fast, then inactivate c) selective blockers of Na+ channels (e.g. tetrodotoxin) block APs d) all the above e) b) and c) are true 33. Which of the following are true after the Na/K pump is blocked? a) as inside Na+ conc rises, Cl- follows and the cell swells

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b) at equilibrium the inside Na+ conc would eventually exceed that outside c) immediately no more APs can be fired d) all the above e) a) and b) only are true 34. Block of conduction after demyelination in Multiple Sclerosis occurs because a) there are no K+ Channels between nodes b) there are no Na+ channels between nodes c) at the demyelinated site, the next node fails to reach threshold d) a) and c) e) b) and c) 35. The Goldman Equation a) predicts the membrane potential based upon the distribution of one ion b) assumes permeability to more than one ion c) predicts the membrane potential based upon the distribution of several ions d) a) and b) are true e) b) and c) are true 36. Lines of evidence for the involvement in the AP of Na+ and K+ channels and lack of involvement of the Na/K pump come from which of the following a) experiments with ouabain b) experiments with tetrodotoxin c) ion substitution experiments d) all the above e) a) and b) only 37. A compound action potential a) is recorded intracellularly b) is recorded extracellularly from a nerve c) is due to the summation of the signals from many nerve fibers firing APs at once d) a) and c) are true e) b) and c) are true 38. The three characteristics of the action potential include which of the following a) a threshold for triggering b) a refractory period c) all or none in size d) all the above e) a) and b) only 39. A membrane potential requires a) different concentrations of sodium ions on the two sides b) active transport for Na+/K+ c) permeability to an ion with different concentrations on the two sides d) all the above e) a) and c) only 40. If an axon conducts an action potential at 5m/sec and is 50cm long, it will take how long to go from one end to the other? a) 10msec b) 50msec c) 100msec d) 0.5 sec e) can't be determined. 41. Which of the following are true? a) action potentials cannot summate b) electrotonic potentials have no refractory period c) electrotonic potentials are not actively propagated d) all the above e) none of the above

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42. If one increases the external K+ concentration slightly around a neuron, a) the top of the action potential will not reach as high (close to +58mV) b) the membrane's resting potential will depolarize c) there will be no effect on either the AP or resting potential d) both a) and b) are true e) none of the above 43. Facilitated diffusion differs from active transport in that a) facilitated diffusion transports against a concentration gradient while active transport does not b) active transport requires expenditure of energy while facilitated diffusion does not c) facilitated diffusion involves special membrane proteins while active transport does not d) facilitated diffusion transports even in the absence of a gradient while active transport does not. e) facilitated diffusion is saturable while active transport is not 44. Secondary active transport a) directly uses ATP for the energy needed to transport b) is a form of diffusion utilizing no energy c) uses an ion concentration difference for energy d) is the second step of a two step process called primary active transport e) is not saturable 45. One basic difference between diffusion through the bilayer and facilitated transport (carriers) is a) diffusion flux has no maximum limit while facilitated transport is limited by the number of carriers b) facilitated transport has no practical limit while diffusion is limited when concentration is increased c) facilitated transport always requires energy expenditure while diffusion does not d) diffusion involves special transporter proteins while facilitated transport does not e) facilitated transport allows accumulation against the gradient while diffusion does not 46. Two chambers containing one liter each are separated by a membrane permeable only to water. Side 1 contains 5.8gm of NaCl and side 2 contains 18gm of glucose. If the molecular weight of NaCl is 58 and that of glucose is 180, which way will water move? a) there will be no water movement since both sides are 0.1M b) water will move into side 1 with the NaCl c) water will move into side 2 with the glucose, since there are more grams of glucose than of NaCl d) The number of grams of NaCl must be doubled since the ions split up in solution, but even so there are still fewer grams than glucose, so water will move toward the glucose (side 2) e) One cannot calculate water flow from this information. 47. At time zero, a membrane permeable only to K+ and Cl- separates 100mM NaCl (side A) from 100mM KF (side B). At equilibrium, a) compartment A will be negatively charged relative to B b) there is measurable net flux of K+ from B to A

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c) there is a concentration gradient favoring Cl- diffusion from A to B, and this gradient is balanced by an electric force favoring diffusion from B to A

d) all the above e) b) and c) only 48. The resting membrane potential a) occurs only in nerve and muscle cells b) is the same in all cells c) is oriented so that the cell’s interior is positive with respect to the extracellular fluid. d) Requires the separation of most of the cell’s charged particles e) None of the above 49. In a resting neuron, a) the plasma membrane is freely permeable to sodium ions b) the concentration of sodium ions is greater inside the cell than outside c) the plasma membrane is completely impermeable to sodium ions d) the permeability of the plasma membrane to potassium ions is about 50X greater than to sodium ions e) none of the above is true 50. The membrane potential of most neurons at rest is a) equal to the equilibrium potential for potassium ions b) equal to the equilibrium potential for sodium ions c) less negative than the equilibrium potential for potassium ions d) more negative that the equilibrium potential for potassium ions e) b) and c) 51. The concentration gradient for Na+ across a nerve cell membrane a) favors its movement into the cell at resting potential b) favors its movement out of the cell at resting potential c) is maintained by the Na/K pump d) a) and c) e) b) and c) 52. The equilibrium potential of a given ion across a membrane is a) a function of the concentration of that ion on both sides of the membrane b) the potential at which there is no net movement of that ion across the membrane c) the potential difference across the membrane at which the electric force favoring diffusion in one direction is equal

and opposite to the diffusion force driven by the concentration difference. d) All the above e) a) and b) only 53. The equilibrium potential for K ions in nerve cells is about –90mV, but the resting membrane potential is about –70mV. Therefore, a) increasing the permeability of a resting neuronal membrane to K ions will make the membrane potential more

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negative b) in nerve cells at rest, there is a net diffusion of K ions out of the cell c) making a neuron’s membrane potential more negative would slow the diffusion of K ions out of it d) all the above e) a) and b) only 54. Which of the following statements concerning the permeability of a typical nerve cell at rest is true? a) the permeability to Na ions is very much greater than the permeability to K ions b) all of the K ion channels in the membrane are open c) the voltage gated Na ion channels are inactivated d) the voltage gated Na ion channels are closed e) none of the above 55. Graded potentials a) include receptor potentials and postsynaptic potentials b) spread decrementally according to the space constant c) include depolarizing and hyperpolarizing potentials d) can be summed e) are described by all the above 56. An action potential in a neuron differs from a graded potential in that a) an AP requires the opening of Ca+2 channels, whereas a graded potential does not b) an AP is propagated without decrement whereas a graded potential is not c) an AP has a threshold and is an all-or-none phenomenon whereas a graded potential does not have a threshold and

is not all-or-none d) a) and b) e) b) and c) 57. Which of the following statements about the phases of an AP are correct? a) during the hyperpolarizing phase, the permeability to sodium ions is greater than its permeability at rest b) during the hyperpolarizing phase, the permeability to potassium ions is greater than its permeability at rest c) during the repolarizing phase, the permeability to potassium ions is greater than it permeability at rest. d) a) and c) e) b) and c) 58. Axons typically have abundant a) voltage-regulated channels for Na+ that open in response to depolarization b) voltage-regulated channels for K+ that open in response to hyperpolarization c) receptor mediated channels for Na+ d) all the above e) a) and b) 59. Which of the following statements concerning the properties of an AP is true? a) the rate of propagation of an AP down an axon is independent of stimulus strength b) APs can be summed c) A supra-threshold stimulus is required to stimulate an AP during the absolute refractory period

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d) The rate of propagation is faster in small diameter axons than in large diameter ones e) The rate of propagation is faster in unmyelinated axons than in myelinated ones. 60. The regions of axon membrane that lie between regions of myelin are the a) islets of Langerhans b) nodes of Ranvier c) synaptic membranes d) glial cells e) dendrites 61. Just after an AP at an excitatory synapse, a) there is an increased permeability of the postsynaptic membrane to both Na and K b) a small hyperpolarization occurs c) an AP in the presynaptic neuron always causes an AP in the postsynaptic neuron d) all the above e) a) and c) only 62. An EPSP in a neuron a) is a direct result of the opening of ligand-gated channels for Na and K ions in the membrane b) is a direct result of the opening of voltage-gated channels for Na and K ions in the membrane c) stabilizes the membrane to stay at its resting potential d) a) and c) e) b) and c) 63. Temporal summation on a postsynaptic membrane a) refers to the effect on the membrane of one or more synaptic events before the effects of a previous synaptic event

have died away. b) refers only to the addition of EPSPs c) refers only to the effect of stimulating different synapses repeatedly d) inevitably leads to APs in the axon e) None of the above are true. 64. A neuron has 3 presynaptic inputs, X, Y and Z. When X and Y are stimulated simultaneously, the postsynaptic neuron reaches threshold and fires an AP. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential. What can you tell about presynaptic inputs Y and Z? a) they are probably both excitatory b) they are probably both inhibitory c) Y is probably excitatory, and Z is probably inhibitory d) Z is probably excitatory and Y is probably inhibitory e) One can tell from this data. 65. The simultaneous stimulation of X and Y (in the above question) is an example of a) temporal summation b) presynaptic inhibition c) spatial summation d) neuronal divergence e) none of the above 66. Which of the following statements about ACh is correct?

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a) ACh is broken down by Choline Acetyltransferase b) ACh binds to nicotinic and muscarinic receptors c) ACh synthesis is catalyzed by acetylcholinesterase d) All the above e) a) and c) only 67. the major excitatory and inhibitory neurotransmitters in the CNS are: a) glutamate and dopamine b) GABA and norepinephrine c) glutamate and GABA d) GABA and glycine e) dopamine and glutamate 68. Which are true? a) all ions with a concentration difference across the membrane contribute to Vm b) if a membrane is at the Goldman potential, there is no net flux of any ion across the membrane c) if a membrane is at the Nernst potential for an ion, there is no net flux of that ion d) all the above e) b) and c) only are true MUSCLE 1)-8) For questions through 6, use the answers below. For this section only, write the letter of the answer next to the number of the question. a) skeletal muscle b) smooth muscle c) cardiac muscle d) cardiac and skeletal muscle e) smooth and cardiac muscle 1) Has the longest twitch duration and slowest contraction. 2) Lacks troponin on thin filaments, and uses calcium triggered phosphorylation of myosin to control contraction instead. 3) Responds to stretch by contracting. 4) Has regular repeating arrays of actin and myosin filaments (sarcomeres). 5) Can develop tension over a greater range of lengths. 6) Responds directly to circulating hormones. 7) Has gap junctions. 8) Has spontaneous production of action potentials. 9. In the sliding filament model of muscle, the reaction generating the tension is said to be between: a) actin and troponin b) actin and tropomyosin. c) tropomyosin and myosin d) troponin and tropomyosin e) actin and myosin 10. ATP is required by muscle: a) for cross-bridge cycling b) for the sarcoplasmic reticulum to pump Ca++. c) to pump Na+ out of the cell. d) all the above. e) a) and c) only. 11. In active muscle contractions, the relationship between net tension (the increase over resting) and muscle length is: (use answers a through e from the next question).

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13. In the resting muscle, the relationship between tension and length is: a) lo b) lo c) lo tension tension tension

length length length d) lo e) lo tension tension

length length 13. The velocity of contraction in an isotonic muscle twitch depends upon the load in the following way: a) b) c) d) e) vel vel vel vel vel load load load load load 14. In an isometric muscle contraction: a) the muscle doesn't shorten and no work is done b) the tension is greatest at longest muscle lengths c) the duration of the shortening is shorter for large loads d) the velocity of the shortening is greater for smaller loads e) c) and d) 15. In an isotonic muscle contraction: a) the velocity of the shortening is greater for smaller loads. b) the muscle doesn't shorten and no work is done. c) the tension is greatest at longest muscle length. d) the duration of the shortening is longer for large loads e) a) and d only. 16. The transverse tubules of the muscle: a) are not continuous with the sarcoplasmic reticulum. b) are continuous with the plasma membrane. c) propagate action potentials over their surface. d) all the above. e) b) and c) only are true. 17. A single AP in a skeletal muscle fiber causes the release of enough Ca++ from sarcoplasmic reticulum: a) to stimulate about half the cross bridges to generate tension; thus single twitches are smaller than tetanic contractions. b) to raise internal Ca++ to about 1mM. c) to stimulate all of the cross bridges to generate tension. d) a) and b) only. e) b) and c) only.

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18. The thick filaments of skeletal muscle are made up of: a) actin and troponin. b) actin, troponin and tropomyosin. c) actin, myosin and tropomyosin. d) myosin only e) actin only. 19. Rigor mortis is caused by: a) failure to pump Na+ back out of M. fiber which keeps fiber depolarized. b) lack of ATP necessary to release myosin cross bridges from actin binding sites. c) lack of Ca++ for contraction. d) failure to generate any more AP's so muscle can't relax. e) bacterial growth in the muscle causing stiffness. 20. Physiologically the substance which is used to regulate muscle tension is: a) Ca++ b) Mg++ c) ATP. d) Na+ e) a), b) and c). 21. Fast oxidative (resistant to fatigue) muscle fibers: a) are larger in diameter than fast glycollytic fibers. b) are higher in myoglobin and vascularization than fast glycollytic. c) produce less lactic acid than fast glycollytic fibers. d) a) and b) only. e) b) and c)only. 22. Fast glycollytic (fatiguable) muscle fibers: a) are present in greater numbers in marathon runners. b) have more mitochondria and oxidative phosph. capacity than the other types. c) produce more lactic acid when active than other types, contributing to the oxygen debt. d) have more myoglobin, making them appear red. e) are smaller in diameter than slow fibers. 23. In heart muscle, the duration of the action potential is: a) much shorter than the contraction and precedes it by about 10 msec. b) much shorter than the contraction and overlaps with it slightly. c) about the same length or just a bit shorter than the contraction. d) much longer than the contraction. e) much shorter by far than the refractory period that follows it. 24. In smooth muscle: a) the membrane potential often responds to hormones, pH and O2 etc. b) the membrane potential often shows spontaneous oscillations and AP's. c) the calcium for contraction comes exclusively from the sarcoplasmic reticulum. d) all the above. e) a) and b) only.

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25. The thin filaments of the skeletal muscle fiber are made up of: a) actin, troponin and myosin. b) actin only c) actin and troponin d) actin, troponin and tropomyosin. e) myosin, troponin and tropomyosin. 26. The region between adjacent Z lines in skeletal muscle fibers is termed: a) the A band b) the I band c) the H zone. d) a sarcomere e) none of the above. 27. In initiating contraction in skeletal muscle, calcium binds to: a) actin b) tropomyosin c) troponin d) myosin e) actomyosin. 28. Fast and slow skeletal muscle fibers can be distinguished by their: a) myosin content. b) susceptibility to fatigue. c) pattern of striations. d) all the above. e) a) and b) only. 29. The process of contraction in smooth muscle: a) depends on Ca++ release only from its sarcoplasmic reticulum. b) involves the combination of Ca++ with calmodulin. c) involves the phosphorylation of myosin. d) does not require the presence of tropomyosin and troponin. e) b), c) and d) are correct. 30. Individual contractions in cardiac muscle fibers: a) always last longer than those in skeletal muscle. b) are always isometric. c) do not involve intracellular Ca++ release d) are always isotonic. e) none of the above. 31. The actin to myosin filament ratio in smooth muscle a) is the same as in skeletal muscle. b) is higher than in striated muscle. c) is higher than in skeletal muscle but not higher than that in cardiac muscle. d) is much lower than in both skeletal and cardiac muscle. e) is higher than in cardiac muscle but not higher than in skeletal muscle. 32. Repeated endurance exercise (such as marathon running) a).increases cardiac capacity b) increases respiratory capacity. c) adds bulk to muscles d) all the above e) a) and b) only. 33. Which of the following are true: a) Two ATP are cleaved per cross bridge motion. b) The heat of recovery after exercise is equal to the initial heat during exercise.

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c) It is not possible to run the 100 yard dash without breathing. d) After glycogen stores are depleted, the marathon runner must stop. e) During a twitch, the calcium that enters the muscle fiber is not sufficient for a full activation of the contractile apparatus. 34. Which of these processes does not require oxygen? a) glycollysis b) Krebs cycle/oxidative phosphorylation c) lactate formation d) anaerobic metabolism e) a), c) and d). 35. Under anaerobic conditions, pyruvate is converted to a) citric acid b) glucose c) NADH d) lactic acid e) glucose-6-phosphate 36. A sarcomere a) is separated by Z-lines b) is the repeating unit of striated muscle c) shortens when a muscle shortens d) contains thick and thin filaments e) all of the above 37. Smooth muscle contraction a) involves troponin b) is regulated by calmodulin binding of Ca++ c) involves actin and myosin d) is not activated by calcium e) c) and b) are correct 38. In cardiac muscle a) there are no sarcomeres b) there is no transverse tubule system c) cells are electrically coupled d) troponin is absent e) all of the above 39. Which of the following are true of the slow muscle fibers? a) have the highest rates of glycollysis b) have the highest levels of myoglobin c) have the highest glycogen content d) a) and c) are true e) b) and c) are true 40. Which of the following are true of the fast-fatiguable muscle fibers? a) have the highest rates of glycollysis b) have the richest supply of capillaries c) are used for fast heavy lifting d) a) and c) are true e) a) and b) are true 41. Which of the following are true of the fast-resistant to fatigue muscle fibers? a) have high levels of myoglobin b) are intermediate in size and glycogen content c) have few capillaries d) all the above e) a) and b) are true 42. Which of the following are true of skeletal muscle length tension relationships? a) the muscle normally operates within 1/3 of its resting length, lo.

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b) stretching the muscle always makes it produce greater active tension. c) stretching the muscle always makes it produce less active tension. d) a) and b) are true e) a) and c) are true 43.Which of the following is true? a) the increase in muscle mass from heavy exercise is due to an increase in the number of muscle fibers b) muscle fibers are composed of many fibrils c) cross bridges exist between muscle fibers to hold them in tight bundles d) in the case of muscle damage, no regeneration of muscle cells is possible in adults e) all muscle fibers extend the full length of the muscle they comprise 44. When a muscle fiber contracts, the a) thick filaments shorten b) cross bridges slide over each other c) thin filaments break down ATP d) cross bridges ratchet the thin filaments along the thick ones e) both the thick and thin filaments shorten 45. The removal of calcium ions from the actin-myosin system causes a) the myosin binding sites on actin to be uncovered by tropomyosin b) tropomyosin to change configuration and thereby move the troponin molecules c) the troponin to move from on top of the cross bridge binding sites on actin d) the myosin binding sites on actin to be covered by tropomyosin e) shortening of the sarcomeres 46. Excitation-contraction coupling a). depends on the release of calcium from the sarcoplasmic reticulum b) is the path from action potential to cross-bridge formation c) depends upon increased cytosolic calcium d) all the above e) a) and c) only 47. In the cross bridge movement step of contraction a) ATP is ultimately the source of energy for this step b) ATP is not hydrolyzed to release its energy during the actual movement c) ATP is responsible for detachment of the cross bridge from the thin filament d) all the above e) a) and c) only 48. Muscle fibers go into rigor mortis because a) sarcoplasmic reticulum releases too much calcium b) ATP levels are depleted c) thick and thin filament cannot contact each other d) bacteria break down muscle tissue e) the muscle fibers dry out 49. Cross bridge activity occurs when a) ATP binds to troponin and exposes cross bridge binding sites

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b) calcium binds to tropomyosin and exposes binding sites c) calcium binds to troponin, which causes changes that expose binding sites covered by tropomyosin d) calcium is released from tropomyosin and causes it to move away from cross bridge binding sites on actin e) calcium is pumped back into the sarcoplasmic reticulum 50. The protein myosin a) comprises the thin filaments in a muscle fiber b) has a tail that forms the cross bridges coming from the thin filaments c) has a globular head with a binding site for actin as well as an enzymatic site d) is only found in smooth muscle fibers e) is only found in cardiac and skeletal muscle fibers 51. The reason that action potentials are able to initiate muscle fiber contraction is that they a) supply the electrical energy that drives muscle contraction b) contribute to the hydrolysis of ATP to yield energy c) cause the pumping of calcium ions from the cytosol to the sarcoplasmic reticulum which enables cross bridge formation d) cause calcium influx from the sarcoplasmic reticulum which enables cross bridge formation e) cause the entry of Na+ which is necessary for cross bridge formation 52. The response of a single muscle fiber to a single action potential is a) a twitch b) a tetanus c) always isometric d) always isotonic e) b) and c) only 53. Which of the following is correct concerning motor neurons a) the muscle fibers in a single motor unit are normally adjacent to one another in a bundle b) the process of increasing the rate of action potentials in a motor unit is called recruitment. c) a single motor neuron normally innervates many muscle fibers d) any one muscle fiber is normally controlled by several motor neurons e) b) and c) 54. Fatigue in muscle a) is due to depletion of ATP b) occurs due to failure of slow muscle fibers c) is correlated with buildup of inorganic phosphate d) all the above e) a) and c) 55. The drug curare, sometimes used in surgery, works at the neuromuscular junction by a) inhibiting release of ACh b) inhibiting acetylcholinesterase c) binding to ACh receptors, but not opening ion channels, thereby preventing synaptic transmission by ACh d) increasing the activity of acetylcholinesterase e) inhibiting reuptake of ACh 56. Comparing smooth muscle with skeletal muscle a) both muscle types are basically the same, but vary only in location in the body and in their innervation

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b) the organization of the contractile filaments in the two types is different c) skeletal muscles are voluntary while smooth muscles are both voluntary and involuntary in their control d) excitation-contraction mechanisms are identical in the two muscle types e) skeletal muscles have only slow myosin while smooth muscles have fast myosin 57. Which of the following statements about skeletal muscle fibers is true? a) slow-oxidative fibers have low myosin-ATPase activity and high oxidative capacity b) fast-oxidative fibers have high myosin-ATPase activity and high oxidative capacity c) fast-glycolytic fibers have high myosin-ATPase activity and low oxidative capacity d) all the above are true e) a) and b) only 58.The length at which a muscle develops the greatest tension is the a) tetanus b) optimal length (lo) c) optimal velocity d) summation e) shortest muscle length 59. Resting skeletal muscle maintains energy reserves in the form of a) glycogen b) creatine phosphate c) ATP d) all the above e) a) and c) only 60. cross-bridge formation in smooth muscle depends upon a) calmodulin binding of calcium b) phosphorylation of myosin light chains c) myosin light chain kinase (MLCK) binding the calcium/calmodulin complex d) all the above e) a) and c) only 61. A single twitch in smooth muscle can last considerably longer than in skeletal muscle because a) the strength of neuronal action potentials tends to be greater in smooth muscles b) calcium is not actively transported out of the cytosol in smooth muscle c) calcium is transported into the cytosol faster in smooth than in skeletal muscle d) the rate of calcium removal in smooth muscle is much slower in smooth than in skeletal muscle e) a) and d) 62. A motor neuron plus the muscle fibers that it innervates is called a a) myofibril b) sarcomere c) motor unit d) tetanus e) recruitment 63. The area where a motor axon contacts the muscle fiber is called a) the neuromuscular junction b) tetanus c) the endplate d) all the above e) a) and c) 64. The process of increasing the number of motor units that are active in a muscle at any given time is called a) summation b) tetanus c) recruitment d) hypertrophy e) atrophy 65. Which of the following are true?

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a) the skeletal muscle fiber's AP is completed before any tension develops in the fiber b) smooth muscle can develop tension over a much narrower range of fiber lengths than can skeletal muscle c) the number of muscle fibers that contract in a motor unit depends upon the strength of the motoneuron AP d) one role of the sarcoplasmic reticulum is to provide the energy for muscle contraction e) smooth muscle is normally under voluntary control 66. During isotonic contraction of a skeletal muscle fiber, a) the sarcomeres shorten b) the A bands shorten c) the I bands shorten d) a) and c) e) b) and c) 67. which of the following statements regarding the shortening of a skeletal muscle fiber are NOT true? a) the sarcomeres shorten b) the distance between the Z lines decreases c) the myofilaments shorten d) the myofilaments slide past each other e) the length of the A bands remains the same 68. In skeletal and cardiac muscle, calcium ions trigger contraction by binding to a) tropomyosin b) actin c) troponin d) myosin e) the thick filament 69. Binding of _______ to myosin permits cross-bridge _______between actin and myosin a) ATP; attachment b) ATP; detachment c) Calcium; attachment d) calcium; detachment e) troponin; detachment 70. ATP is necessary for each of the following mechanisms or functions in skeletal muscle EXCEPT a) pumping of calcium ions back into the sarcoplasmic reticulum b) dissociation of myosin from actin c) release of calcium ions from the sarcoplasmic reticulum d) movement of the myosin cross bridges e) maintenance of Na and K ion gradients at the plasma membrane. 71. An AP in the sarcoplasmic membrane rapidly spreads to the central portions of a muscle fiber by means of a) the Z lines b) sarcoplasmic reticulum c) H zone d) transverse tubules e) pores in the plasma membrane 72. Curare a) is an autoimmune disease b) blocks acetylcholinesterase c) is a muscarinic ACh antagonist d) is an nicotinic ACh antagonist e) b) and c) 73. During an isometric contraction of a skeletal muscle, a) the I bands shorten and the A bands stay the same b) the thick and thin filaments slide past each other c) sarcomere length does not change d) both a) and b) e) none of the above 74. During any isometric twitch in a skeletal muscle,

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a) load exceeds tension b) tension exceeds load c) tetanus occurs d) a) and b) e) a) and c) 75. Which of the following statements explains how tetanus is generated in spite of the all-or-none AP? a) During a single AP, there is not enough time for all of the calcium in the SR to diffuse into the cytoplasm and bind

troponin b) Skeletal muscle fibers have short refractory periods. c) APs in skeletal muscle fibers can summate d) After a single AP, there is not enough time for tension to fully stretch the SEC before the calcium is pumped back

into the SR e) A) and B) 76. Which of the following statement regarding skeletal muscle contraction are true? a) the tension developed during the contraction is dependent upon the initial length of the fiber. b) The longer the muscle fiber before contraction, the greater the tension. c) The greater the frequency of APs, the greater the tension, up to a plateau (tetanus). d) a) and b) e) a) and c) 77. The optimal length of a skeletal muscle is a) the length at which the muscle can generate the maximal tetanic tension b) the shortest length the muscle can achieve while attached to the bone, because the amount of overlap between thick

and tin filaments is maximal then. c) Approximately the same as its resting length d) a) and b) e) a) and c) 78. The first means by which ATP is produced at the onset of contractile activity in skeletal muscle is a) transfer of energy and phosphate from creatine phosphate to ADP b) oxidative phosphorylation c) glycollysis d) oxidation of fatty acids e) catabolism of myoglobin 79. When a muscle has been contracting for an extended period of time(hours), the primary source of ATP is a) transfer of energy and phosphate from creatine phosphate to ADP b) glycollysis c) lactic acid d) oxidative phosphorylation using fatty acids e) catabolism of myoglobin 80. In muscles recovering from heavy exercise, a) oxygen is used for oxidation of lactic acid metabolites to generate ATP b) ATP is used to synthesize glycogen from glucose c) ATP is used to phosphorylate creatine d) ATP is used to pump Na out and K into the muscle fiber e) all the above 81. Which of the following statements regarding skeletal muscle is true? a) some skeletal muscle fibers have pacemaker activity. b) Skeletal muscle fibers are joined together by gap junctions c) Skeletal muscle fibers will contract when excitatory neural input exceeds inhibitory neural input at the NMJ.

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d) Skeletal muscle fibers will contract when excitatory neural input substantially exceeds inhibitory neural input at the motorneuron.

e) None of the above 82. Ron is a sprinter who specializes in fast powerful bursts of speed followed by periods of rest. John is a marathon runner, who runs for hours at a time. Compared to John, Ron is likely to have a) legs with a larger diameter b) legs with a smaller diameter c) hypertrophy of type I (slow) muscle fibers d) a) and c) e) b) and c) 83. Compared to Ron, John is likely to have a) more glycogen stored in his type IIb (fast glycollytic) muscle fibers b) more mitochondria in his type I (slow) and IIa (fast oxidative) muscle fibers c) more myoglobin in his type IIb (fast glycollytic) muscle fiber d) a) and c) e) b) and c) 84. Smooth muscle contraction is mediated by the phosphorylation of ______, which occurs as a result of a chain of biochemical events including the binding of calcium to _______. a) ADP; calmodulin b) calmodulin; myosin c) actin; tropomyosin d) myosin; troponin e) myosin; calmodulin 85. A major difference between smooth muscle and skeletal muscle is that a) myosin is the regulatory protein in smooth muscle b) myosin is the regulatory protein in skeletal muscle c) skeletal muscle may exhibit spontaneous activity d) only skeletal muscle requires increased calcium ion concentration in the cytosol for contraction e) none of the above 86. Excitation-contraction coupling a) in skeletal muscle requires the influx of extracellular calcium ions b) in smooth muscle requires the influx of extracellular calcium ions c) in all kinds of muscle, requires the release of calcium ions from the sarcoplasmic reticulum d) a) and b) e) b) and c) 87. Myasthenia graevis a) is an autoimmune disease b) occurs when the nerve terminal cannot secrete enough ACh to cause the muscle fiber to reach threshold c) can be treated with a drug that inhibits acetylcholinesterase d) a) and b) e) a) and c) NMJ/SYNAPSES 1. The endplate potential:

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a) normally triggers an action potential. b) has a slight refractory period. c) is produced by a change in permeability to Na+ and K+. d) all the above. e) a) and c) only. 2. A chemical transmitter may be removed from a synapse by: a) chemical alteration. b) diffusion. c) reuptake into the synaptic terminal. d) all the above. e) a) and c) only. 3. Calcium ions are important at the neuromuscular junction because: a) they enter through the AChR channel in very large quantities. b) they are necessary for transmitter release from the presynaptic terminal. c) they determine the reversal potential for the end plate potential. d) a) and c) are true. e) b) and c) are true. 4. Miniature endplate potentials (mEPPs): a) are recorded postsynaptically. b) are recorded presynaptically. c) are attributed to random release of ACh vesicles. d) are endplate potentials caused by small AP's in the nerve. e) a) and c) only. 5. Strength of muscle contraction is controlled physiologically by: a) the frequency of AP's in the nerve fiber and its muscle fibers. b) the size of the endplate potential. c) the duration of the endplate potential d) the number of motor units active. e) a) and d) are true. 6. The evidence that Acetylcholine is the transmitter at the neuromuscular junction includes which of the following: a) high Mg++, low Ca++ block the endplate potential. b) ACh is released by the nerve terminal and depolarizes muscle fibers. c) both ACh esterase and choline acetyl transferase are present at the synapse. d) all the above. e) b) and c) only. 7. Skeletal motorneurons

a) are the final common pathway to the muscle. b) have their cell bodies in the spinal cord. c) receive synaptic input only from muscle stretch receptors. d) a) and b) only. e) a) and c) only.

8. The stretch reflex for muscle contraction: a) is a monosynaptic reflex involving no interneurons b) is a polysynaptic reflex involving one interneuron c) plays no role in postural control since only large stretches trigger it. d) is not dependent upon sensory information. e) a) and d) only.

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9. The withdrawal reflex (e.g. touching a hot pan): a) sometimes produces extension of the opposite limb. b) occurs before pain is consciously detected. c) always produces flexion of the same limb. d) all the above e) a) and c) only. 10. Motorneurons in the spinal cord receive inhibitory synaptic input (IPSPs) a) directly from sensory neurons (e.g. stretch receptors). b) from both sensory neurons and interneurons. c) indirectly from sensory neurons by way of interneurons. d) only during the stretch reflex in an antagonist muscle. e) c) and d) only. 11. Which of the following are true?

a) reflex response to pain(e.g. withdrawal) cannot be consciously suppressed. b) the withdrawal response to pain is mediated by a neural reflex. c) unmyelinated fibers subserve burning pain; myelinated A-delta fibers subserve the sharp prickling variety of

pain. d) all the above. e) b) and c) only.

12. Release of transmitter from presynaptic nerve terminals: a) cannot exceed the number of molecules contained in a single vesicle. b) is independent of the voltage in the presynaptic terminal. c) occurs in small packets called quanta, each thought to equal the contents of one vesicle. d) requires Ca++ influx into the presynaptic terminal. e) both c) and d) are correct. 13. The endplate potential (EPP) in muscle and EPSPs in the CNS differ in that: a) the EPP always reaches threshold while a single EPSP may not. b) the EPSP is larger than the EPP. c) the EPP requires presynaptic Ca++ entry while the EPSP does not. d) the EPSP is all-or-none while the EPP is graded. e) none of the above. The two are identical. 14. The evidence that transmission at the neuromuscular junction is not electrical is: a) the presence of a delay between the action potential in the nerve terminal and the rise of the EPP in the muscle fiber. b) the absence of a low resistance pathway between the cytoplasm of the nerve terminal and that of the muscle fiber. c) the absence of gap junctions between the nerve terminal and the muscle fiber in electron micrographs. d) all the above e) a) and c) only.

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15. The action of curare is a) to block the enzyme acetylcholinesterase that breaks down ACh. b) to block release of vesicles containing ACh from the presynaptic terminal c) to block the acetylcholine receptors on the postsynaptic muscle membrane d) a general anaesthetic e) both b) and d) 16. Which of the following are true? a) The acetylcholine receptor channel is selective for Na+ ions. b) The Endplate Potential (EPP) can be recorded anywhere on the muscle fiber. c) In myelinated nerve fibers, sodium channels occur only at the nodes of Ranvier. d) All the above. e) b) and c) only. 17. The acetylcholine receptor channel differs from the Na+ channel since a) its opening is not voltage dependent. b) it is lined with positive charges. c) it allows K+ through d) all the above e) a) and c) only 18. An IPSP a) is more negative than resting Vm b) is less negative than resting Vm c) results mainly from an increase in PK+ or PCl- d) results mainly from an increase in PNa+ e) a) and c) are correct 19. Evidence for ACh as the transmitter at the NMJ include: a) Enzymes for synthesis and breakdown of ACH are present at the NMJ and when blocked affect transmission. b) Conditions of low Ca++/high Mg++ block release of ACh and block transmission. c) Artificially applied ACh produces a depolarization like the EPP and ACh is released during the nerve AP. d) all the above e) a) and c) only 20. Blocking acetylcholinesterase (AChE) at the NMJ a) blocks transmission b) prolongs the EPP and the action of ACh c) causes the muscle to remain contracted for long periods of time d) all the above e) b) and c) only 21. The action of ACh at the NMJ is normally is terminated by a) diffusion away from the endplate b) reuptake into the nerve terminal c) hydrolysis by acetylcholinesterase d) all the above e) b) and c) only 22. Myasthenia Gravis: a) is an autoimmune disease b) causes decreased release of ACh from the nerve terminal c) can cause paralysis when too few ACh receptors are present for the muscle fibers to reach threshold d) all the above e) a) and c) only

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23. Evidence for vesicular storage and release of neurotransmitter at the NMJ include a) Isolated vesicles contain ACh, known to be the neurotransmitter b) With fast freezing techniques, one can see vesicle fusion to membrane in EM c) After long, high frequency stimulation, vesicles are depleted from the terminals d) all the above e) a) and b) only 24. Neuromuscular synaptic transmission and synaptic transmission in the CNS differ in that a) the EPP is always greater than threshold but single EPSPs in CNS are almost always very small b) the muscle receives only excitation but CNS neurons get both inhibitory and excitatory synapses c) each muscle fiber receives only one nerve terminal while CNS neurons each receive 1000s of synapses d) all the above e) b) and c) only 25. Reciprocal innervation refers to the fact that a) when one muscle is contracted, the antagonist is relaxed b) the muscles in the opposite limb are controlled in the opposite way c) motor neurons innervate each other reciprocally d) all the above e) a) and b) 26. Which of the following are true? a) there are more motorneurons than interneurons b) interneurons are only inhibitory c) interneurons contact muscle fibers d) interneurons form action programs e) all the above 27. The sensory structure that detects muscle stretch is called a) the neuromuscular junction b) the muscle spindle c) the golgi tendon organ d) the endplate e) the synapse 28. The withdrawal reflex for limb flexion a) is a monosynaptic reflex b) is a polysynaptic reflex c) occurs before pain reaches consciousness d) a) and c) e) b) and c) 29. Which of the following are true? a) the dorsal roots carry sensory information into the spinal cord b) the ventral roots carry motor axons out to muscles c) both are mixed sensory and motor d) the dorsal roots carry motor axons e) both a) and b) 30. For EPSPs in the motorneuron in the spinal cord, a) the transmitter is glutamate b) the transmitter opens channels for both Na+ and K+ c) the excitation comes only from stretch receptors d) all the above e) a) and b) 31. The viral disease that results in the death of motorneurons resulting in paralysis is called

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a) Myasthenia gravis b) polio c) botulism d) multiple sclerosis e) strep 32. A given neuron can a) be either a presynaptic neuron or a postsynaptic neuron, but not both b) receive information from more than one other neuron c) transmit information to more than one other neuron d) all the above e) b) and c) only .