BIOB34H3 Lecture Notes - Lecture 24: Nernst Equation, Fluid Compartments, Extracellular Fluid

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3 Dec 2018

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Resting membrane potential results from there is an ion composition difference between the intracellular and extracellular fluids, so this leads to an equilibrium that has to be met. For potassium, it is high in concentration in the intracellular fluid. Therefore, it has to diffuse to the extracellular fluid (to try to reach equilibrium); however, since potassium is positively charged, by leaving the intracellular fluid, it makes the intracellular fluid more negative (since positive charges disappear). So, some potassium needs to come back to the intracellular fluid. By doing this simultaneously, it"ll eventually reach an equilibrium where both concentrations are equal on both sides, as well as charges are equal on both sides (therefore, concentration gradient = electrical gradient). To find the equilibrium potential for an ion (veq), we gotta use the nernst equation. T is temperature (in terms of kelvin). z is that charge of the ion (for potassium is.

Related Questions

Santiago Ramon y Cajalâs theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohmâs law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

I need help answering this question:

Observation: A strange deep sea creature has been discovered. You are recording from a neuron in itâs brain with an electrode. Upon electrical stimulation, you observe change in voltage that resembles an action potential: the voltage rises, shoots up when it crosses a threshold, and then rapidly falls back to resting potential. Looking at the ions inside and outside the cell, you find that there is a high concentration of positively charged Lithium ions outside the cell and low concentration inside the cell. There is also a high concentration of potassium ions inside and low outside. Finally, there is an equal amount of Chloride ions on both sides. Strangely enough, there arenât any Sodium ions around.

Based on these observations, you ask âIf there is no sodium, what ion is mediating the âaction potentialâ?â

In 100 words or less: 1. Formulate a hypothesis as to what ion might be mediating the action potential.2. Design an experiment to test your hypothesis. 3. State what outcome would confirm your hypothesis.

BIOB34H3 Lecture Notes - Lecture 24: Nernst Equation, Fluid Compartments, Extracellular Fluid

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