Phgy 216 Midterm Exam (2026): High-Yield Questions With Accurate,

PHGY 216 MIDTERM EXAM (2026): HIGH-YIELD QUESTIONS WITH ACCURATE, VERIFIED ANSWERS A+ GRADE GUARANTEED Cellular & Membrane Physiology 1. Calculate the Nernst potential for K at 37C if [K] = 5 mM and [K] = 150 mM. Answer: E = (61.5/z) log([K]/[K]) = 61.5 log(5/150) = 61.5 log(0.0333) = 61.5 (-1.48) = -91 mV 2. Why is the resting membrane potential (-70 mV) slightly less negative than E (-91 mV)? Answer: Because the membrane has a small but significant permeability to Na at rest. Na influx slightly depolarizes the cell from the K equilibrium potential. 3. Describe two mechanisms that could cause hyperpolarization of a neuron. Answer: 1) Increased K efflux (opening of K channels). 2) Increased Cl influx (opening of Cl channels, if E_cl is negative to RMP). 3) Decreased Na or Ca influx. Neurophysiology & Synapses 4. How does tetrodotoxin (TTX) affect the action potential? Answer: TTX blocks voltage-gated Na channels. This prevents the rapid upstroke/ depolarization phase of the action potential, leading to a complete block of signal conduction. 5. What is an IPSP and how is it generated? Answer: An Inhibitory Post-Synaptic Potential is a local hyperpolarization that moves the membrane potential away from threshold. It