PNB 2274 EXAM 2 PRACTICE QUESTIONS AND ANSWERS

PNB 2274 EXAM 2 PRACTICE QUESTIONS AND ANSWERS The region of the sarcomere containing only actin filament - Ans:-I band Reflexes are classified by each of the following EXCEPT: - Ans:-by the response they generate The mechanism of contraction in smooth muscle is different from skeletal muscle in that - Ans:- Smooth muscles use calmodulin, whereas skeletal muscles uses troponin as calcium sensors. NS302 is a compound that promotes the binding of calcium from calmodulin. Based on your knowledge on smooth muscle physiology, what will be the most likely effect if you apply NS302 inside a smooth muscle? - Ans:-Smooth muscle relaxation will slow down because calcium will stay bound longer to calmodulin further promoting MLCK activation Which of the following statements regarding reflexes is correct - Ans:-Reflexes preserve homeostasis In a motor neuron, in which region of the cell would you expect to find the least number of voltage gated sodium channels? - Ans:-Synaptic Knob Which of the following events are FALSE about the peak of the action potential when Vm is most depolarized (~ +30mV)? - Ans:-The inactivation gate of voltage gated sodium channels is OPEN ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/6 By increasing twitch frequency, muscles can generate: - Ans:-Greater tension, unfused tetanus, & fused tetanus While working in an electrophysiology laboratory, an undergraduate student measures the resting membrane potential (Vm) of a mammalian cell to be +70mV rather than the typical -70mV. The discrepancy is likely due to - Ans:-The student measuring the potential outside the cell relative to the inside The afferent (sensory) and efferent (motor) axons together form the - Ans:-Peripheral nervous system During repolarization of the action potential (going from +30mV down to -80mV) - Ans:-The equilibrium potential for K+ [EK] is approached What would most likely happen if the concentration of calcium ions outside a neuromuscular junction was decreased? - Ans:-Less neurotransmitter would be released from a presynaptic terminal in response to an action potential. Stargazer mice have difficulty maintaining posture and moving normally. This defect has been attributed to a defect in some potassium channels that allows Na+ as well as K+ to pass through the channel. Increasing the sodium permeability will have what effect on the membrane potential of the neuron? - Ans:-The membrane potential will become less negative ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/6 The effect of a particular neurotransmitter is dependent upon the properties of the___, not the ___. - Ans:-Receptor, neurotransmitter Which of the following is TRUE with regard to the relative refractory period? - Ans:-It could allow an action potential of much smaller amplitude to proceed along the length of an axon Which of the following statements about the equilibrium potential for an ion are TRUE? - Ans:-If the concentration gradient of the ion changes, the equilibrium potential will also change. Which of the following is an important function of ATP in muscle? (A) it is required for the dissociation of myosin from actin. (B) it is hydrolyzed by the ATPase that pumps calcium ions into the sarcoplasmic reticulum. (C) it is used for the phosphorylation of myosin in smooth muscle. (D) it directly activates ryanodine receptors - Ans:-Only A, B, and C is correct The characteristic of muscles that allows them to return to their original