HMB201H1 Lecture Notes - Lecture 5: Voltage Clamp, Patch Clamp, Resting Potential

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14 Nov 2012

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When membrane potential is at rest then its voltage is -70mv which is the normal membrane potential. Depolarization: when the sodium levels are high and the membrane potential is more positive is highly negative. Hyper polarization: when potassium levels are high and the membrane potential. Repolarization: the membrane returns to the resting membrane potential. The goldman equation describes the resting membrane potential: Gated ion channels allow neurons to alter their membrane potentials: If the membrane potential is not permeable to the ions that pass by, then the ions won"t be efficient to work with the membrane potential and signals won"t be sent. However, if the membrane potential is permeable, then ions will work with the membrane potential to send signals which is important. It happens by changing the permeability of the membrane potential by the addition of sodium and potassium ions. Note: the changing of the permeability of the membrane potential gives electrical signals.

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

1. The plasma membrane of rod and cone cells are

a) At resting potential in the dark and deploarized in thelight

b) At resting pootential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperpolarized in the light

d) Hyperpolarized in the dark and at resting potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

2. The equilibrium potential of K+ ions in nerve cells is about-90mV. The membrane potential of a typical nerve cells at rist is-70mV. Therfore

a) Increasing the permeability of a resting neuronal membrane toK+ ions will increase the membrane potential (that is, make it morenegative, inside with respcect to outside)

b) In nerve cells at rest, there is a net diffusion of K+ ionsout of the cell

c) Increasing the membrane potential of a nerve cell would slowthe diffusion of K+ ions out of it.

d) K+ is not the only ion that is permeable at rest

e) All of the above

3. Which of the following is responsible for the replarizingphase of the action potential?

a) Voltage-gated Na+ channels are opened.

b) The Na+-K+ pump restores the ions to theri original restingstate.

c) The permeability to Na+ increases greatly.

d) ATPase destroys the energy supply that was maintaining theaction potential at its peak.

e) The permeability to K+ increases greatly while that to Na+decreases

4. The Relative refractory period of an axonm conincides withthe period of

a) Activation and inactivatioin of voltage-gated Na+channels

b) Increased Na+ flux into the cell

c) Increased K+ flux into the cell

d) Increased K+ flux out of the cell

e) Increased Na+ flux out of the cell

5. The plasma membranes of rod and cone cells are

a) At resting potential in the dark and epolarized in thelight

b) At resting potential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperoplarized in the light

d) Hyperpolarized in the dark and tat resing potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

i choose aba for those 3 neuroscience question. but could any one help me if i got right?

5. Patch clamp studies have demonstrated that the following is trueâ¦

a. individual channels carry currents that do not predict the macroscopic current carried by the entire population in an axon

b. ion selectivity varies greatly among individual channels of a particular type (e.g. voltage-gated sodium channels)

c. channel behavior includes random fluctuations

d. individual voltage-gated sodium and potassium channels always open when the membrane is depolarized

7. The following is true regarding membrane property known as thresholdâ¦

a. it is primarily determined by the phospholipid composition of the membrane

b. it is strongly dependent upon the voltage-dependence of the voltage-gated sodium channels

c. it usually occurs when the membrane is hyperpolarized beyond the resting potential

d. it occurs when there is less depolarizing current than the leakage currents e. mutations in the sodium channel S4 domain would not be expected to influence threshold

8. Which of the following is a potential advantage of electrical synapses over chemical synapses?

a. their strength can be modulated at many different steps of synapse function

b. neurotransmitters can bind to distinct receptor types present at the same synapse

c. they can allow second messengers to pass between neurons

d. signals can pass more slowly preventing over-stimulation in the brain e. they help ensure that neurons are not synchronously active

HMB201H1 Lecture Notes - Lecture 5: Voltage Clamp, Patch Clamp, Resting Potential

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