K+ inside a cell = 150 mM; K+ outside a cell = 5 mM
Na+ inside a cell = 5 mM; Na+ outside a cell = 150 mM
Stop & Think question
What is the polarity of the resting membrane potential (voltage)? Negative
What does it mean that the voltage just inside the membrane is negative? B
Membrane of most cells contains K+ leak channels…..b
What will happen to the resting membrane potential if the extracellular K+ concentration is increase? Less negative
What happens to diffusion of K+ leaving the cell if you increase extracellular K+? decreases diffusion of K+ out of the cell
Which way would Na+ move across the membrane if there wer open Na channels? A. into the cell
The membrane has open K+ channels and changing….B. mostly closed
1. A negative membrane potential was recorded when the tip of the microelectrode was:
a. In the extracellular solution just outside the cell body
2. Which of the following caused a change in membrane potential from -70 to -40 in the cell body?
a. An increase in extracellular K+
3. Which of the following has the most negative voltage?
a. Between the outside of the axon and outside the cell body with control K+ ECF
b. Between the outside of the axon and outside the cell body with High K+ ECF
c. Between the inside of the axon and the outside of the axon with control K+ ECF
d. Between the inside of the axon and the outside of the axon with High K+ ECF
1 = c; 2= e; 3 = c; 4 = c
Stop& Think Questions
The adequate stimulus for a Pacinian corpuscle is pressure or vibration on the skin. Which of the following modalities will induce the largest amplitude receptor potential in the Pacinian corpuscle? C. moderate-intensity pressure
1. A very intense stimulus can sometimes stimulate sensory neurons that have evolved for a different modality. Thus, with a blow to the eye, one “sees stars/” In this example the... [continues]
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