General & Nerve-Muscle Physiology

Topics in this chapter

• Resting Membrane Potential
• Action Potentials
• Nerve Conduction
• Neuromuscular Junction
• Excitation-Contraction Coupling
• Muscle Contraction Mechanics

Practice questions

1. Question 1Q-CE60D3

   A 24-year-old medical student is studying action potential generation in the giant axon of a squid. While recording the membrane potential, a specific neurotoxin is applied that completely abolishes the early inward current without affecting the delayed outward current. Which of the following channels was most likely blocked?

   1. A.Voltage-gated sodium channels
   2. B.Voltage-gated potassium channels
   3. C.Inward rectifier potassium channels
   4. D.L-type calcium channels
   See the answer and solution
2. Question 2Q-5AA0FE

   During an experiment on skeletal muscle contraction, a muscle fiber is stimulated to contract isometrically. Which of the following parameters remains constant throughout the contraction?

   1. A.Length of the muscle fiber
   2. B.Tension developed by the muscle
   3. C.Length of the I-band
   4. D.Length of the A-band
   See the answer and solution
3. Question 3Q-F528C3

   A researcher is measuring the resting membrane potential of a mammalian nerve fiber. Which of the following ions has the highest membrane permeability at rest and therefore contributes the most to the resting membrane potential?

   1. A.Sodium (Na+)
   2. B.Potassium (K+)
   3. C.Chloride (Cl-)
   4. D.Calcium (Ca2+)
   See the answer and solution
4. Question 4Q-4D3A59

   Which of the following describes the molecular mechanism responsible for the absolute refractory period of a nerve action potential?

   1. A.Activation of voltage-gated potassium channels
   2. B.Inactivation of voltage-gated sodium channels
   3. C.Hyperpolarization due to sustained potassium efflux
   4. D.Depletion of intracellular ATP
   See the answer and solution
5. Question 5Q-C18456

   During excitation-contraction coupling in skeletal muscle, calcium ions are released from the sarcoplasmic reticulum into the sarcoplasm. Which specific protein do these calcium ions bind to in order to initiate contraction?

   1. A.Tropomyosin
   2. B.Troponin C
   3. C.Myosin light chain
   4. D.Alpha-actinin
   See the answer and solution