Physio animal. Ejercicio resuelto, Ejercicios de Fisiología Animal

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Exercise 3: Neurophysiology of Nerve Impulses: Activity 1: The Resting Membrane Potential Lab Report

Pre-lab Quiz Results You have not completed the Pre-lab Quiz.

Experiment Results Predict Question: Predict Question: Predict what will happen to the resting membrane potential if the extracellular K+ concentration is increased. Your answer : a. The resting membrane potential will become more negative.

Stop & Think Questions: What is the polarity of the resting membrane potential (voltage)? Your answer : a. positive Correct answer: b. negative

What does it mean that the voltage just inside the membrane is negative? You correctly answered: b. There are more negative charges than positive charges just inside the membrane.

The membrane of most cells, including neurons, contains passive, open, K+ leak channels. Given the normal K+ concentrations and the resultant concentration gradient, which direction would K+ be expected to move (diffuse) through these leak channels? Your answer : a. into the cell Correct answer: b. out of the cell

What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell? You correctly answered: b. It decreases the net diffusion of K+.

Which way would Na+ move across the membrane if there were open Na+ channels? Your answer : b. Na+ would diffuse out of the cell. Correct answer: a. Na+ would diffuse into the cell.

The membrane has open K+ channels, and changing extracellular K+ concentration results in a change in membrane potential. Changing the extracellular Na+ concentration does not significantly change the membrane potential. What do your results suggest about the number or state (open or closed) of Na+ channels in the resting membrane of a neuron? You correctly answered: b. Na+ channels are mostly closed.

Experiment Data:

Extracellular Fluid (ECF) Microelectrode Position Voltage (mV) Control Cell body extracellular 0 Control Cell body intracellular - Control Axon extracellular 0 Control Axon intracellular - High K+ Axon intracellular - High K+ Axon extracellular 0 High K+ Cell body extracellular 0 High K+ Cell body intracellular - Low Na+ Cell body intracellular - Low Na+ Cell body extracellular 0 Low Na+ Axon extracellular 0 Low Na+ Axon intracellular -

Post-lab Quiz Results You scored 100% by answering 3 out of 3 questions correctly.

1. A negative membrane potential was recorded when the tip of the microelectrode was You correctly answered: d. both inside the cell body and inside the axon.
2. Which of the following caused a change in membrane potential from -70 to -40 in the cell body? You correctly answered: a. an increase in extracellular K+
3. Which of the following has the most negative voltage? You correctly answered: c. between the inside of the axon and the outside of the axon with control K+ ECF

Review Sheet Results You have not completed the Review Sheet.