PhysioEx Lab Report
Exercise 3: Neurophysiology of Nerve Impulses Activity 1: The Resting Membrane Potential Name: Sara Ross Date: 3 February 2023
Session ID: session-5e0b3692-204e-742e-0f86-73bf62b54b4c
Pre-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly
1 What is the approximate concentration of K* inside a typical cell (intracellular concentration)?
You correctly answered: 150 mM.
2 What is the approximate concentration of K* outside a cell (extracellular concentration)?
You correctly answered: 5 mM
3 What is the approximate concentration of Na* inside a cell (intracellular concentration)?
You correctly answered: 5 mM
4 What is the approximate concentration of Na* outside a cell (extracellular concentration)?
You correctly answered: 150 mM.
Experiment Results Predict Question
1 Predict Question: Predict what will happen to the resting membrane potential if the extracellular K* concentration is increased
Your answer: The resting membrane potential will become less negative.
Stop & Think Questions
1 What is the polarity of the resting membrane potential (voltage)?
You correctly answered: negative.
2 What does it mean that the voltage just inside the membrane is negative?
the membrane.
3 The membrane of most cells, including neurons, contains passive, open, K*Ieak channels
Given the normal K* concentrations and the resultant concentration gradient, which direction would K* be expected to move (diffuse) through these leak channels?
You correctly answered: out of the cell
4 What effect does increasing extracellular K* have on the net diffusion of K *out of the cell?
You correctly answered: It decreases the net diffusion of K +
5 Which way would Na* move across the membrane if there were open Na *channels?
You correctly answered: Na* would diffuse into the cell.
6 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: Na* channels are mostly closed.
Experiment Data
Extracellular Fluid (ECF)
Microelectrode Position
Voltage (mV) 0 -70 0 -70 -40 0 0 -40 -72 0 0 -72
Control Control
Cell body, extracellular Cell body, intracellular
Control
Axon, extracellular
Control
Axon, intracellular
High K+ High K+
Axon, intracellular
Axon, extracellular
High K+
Cell body, extracellular
High K+ Low Na+ Low Na+ Low Na+ Low Na+
Cell body, intracellular
Cell body, intracellular
Cell body, extracellular Axon, extracellular Axon, intracellular
ECF = Control, Cell body, extracellular, Voltage = 0 40 Membrane Potential (mV) .60 0g. 0 2 3 4 5 6 7 8 9 10 Time (sec)
ECF = Control, Cell body, intracellular, Voltage = -70 40 Membrane Potential (mV) -60 80 0 1 2 3 4 5 6 7 8 9 10 Time (sec)
ECF = Control, Axon, extracellular, Voltage = 0 40 Membrane Potential (mV) .60 80 0 1 2 3 4 5 6 7 8 9 10 Time (sec)