BIOL123 Lecture Notes - Lecture 10: Resting Potential, Electrochemical Gradient, Active Transport

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brownmole786

7 Aug 2018

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Voltage difference across a membrane due to a slight excess of positive ions on one side and of negative ions on the other. Inside of the cell membrane is ve: outside of the cell membrane is +ve, uneven distribution due to. Ve resting membrane potential: excess of +ve ions on the extracellular side, na+ ions 30% more outside of the cells, more ve ions on the cytosolic side, more k+ inside the cell. Driving force that determines which way an ion will move across a membrane; consists of the combined influence of the ion"s concentration gradient and the membrane potential. Concentration gradient + membrane potential (both forces influence the passive transport of charged molecules) Coupled transporters: transfer of two solutes moves one solute down its electrochemical gradient (downhill, energy released by this movement drives the transport of a second solute against its concentration gradient (uphill) A transporter that transfers two different solutes across a cell membrane in the same direction.

Related Questions

Why do ion channels not function like open pores?

What is membrane potential?

How do K⁺ leak channels work? Why is the membrane potential of a resting cell negative?

What is patch clamp recording? What is one of the major insights gained from patch clamp reporting experiments?

Compare and contrast the three types of gated ion channels.

Be familiar with the different parts of a neuron.

During an action potential, what happens to the membrane potential, voltage-gated Na⁺ channels, Na⁺ ions, voltage gated K⁺ channels, K⁺ ions, and Na⁺-K⁺ ion pumps?

When an action potential reaches a synapse, what happens to the Ca²⁺ channels, Ca²⁺ ions, neurotransmitters, transmitter-gated ion channels, and the post synaptic neuron?

What effect do excitatory or inhibitory neurotransmitters have on postsynaptic cells?

What is an example of a mechanically gated ion channel?

6. Consider the presence of hemoglobin in the catheter bag. Whatsymptom would this loss of

hemoglobin most strongly and immediately be linked to in thepatient?

A. Loss of blood volume

B. Loss of heartbeat

C. Drop in blood oxygen saturation

D. Liver failure

When a neuron is stimulated, the area of the membrane at thepoint of stimulation becomes

more permeable to Na+. If a cell starts at resting potential(-70mv), and is then stimulated:

A. The membrane voltage will become < -70mV, because Na+will move OUT of the cell.

B. The membrane voltage will become > -70mV, because Na+will move OUT of the cell.

C. The membrane voltage will become < -70mV because Na+will move INTO the cell.

D. The membrane voltage will become > -70mV because Na+will move INTO the cell.

. At the peak of the action potential, the Na+ voltage-gatedchannels close, and K+ voltage-gated

channels open in response to the positive membrane potential.In order to return the cell to its

negative resting potential quickly:

A. K+ will diffuse along its concentration gradient INTO thecell.

B. K+ will diffuse along its concentration gradient OUT of thecell.

C. Na+ will reverse its direction of diffusion OUT of thecell.

D. The sodium-potassium pump will move Na+ OUT of the cell andK+ INTO the cell.

E. None of the above would return the cell to its negativeresting potential quickly.

You experiment with higher concentrations of toxin and findcases when the cell could not

repolarize at all or, if it began to repolarize, itimmediately depolarized again. This tells you that

the toxin:

A. Prevents voltage-gated K+ channels from opening.

B. Increases the speed that the Na+ ion channels open.

C. Prevents the Na+ ion channels from closing.

D. Makes the Na+ ion channels close too soon.

E. Doesn

lavenderclam549

What would be most strongly affected by a drug that inhibited the opening of voltage-gated potassium channels (also known as delayed rectifiers)?

A. Falling phase of an action potential

B. Rising phase of an action potential

C. Resting membrane potential

D. Threshold for an action potential

Why does the voltage during the undershoot phase of the action potential become more negative than the resting membrane potential?

A. During the undershoot potassium ions are flowing into the cell due to the reversal of the potassium concentration gradient occurring during the action potential

B. The undershoot phase results from a delay in the activation of sodium channels, resulting in some sodium channels being open after the voltage-gated potassium channels have closed. C. The potassium conductance is higher during the undershoot than during the resting membrane potential.

D. The concentration gradient for potassium has been reversed as a result of the action potential, and the undershoot phase lasts until this the concentration gradient is restored.

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BIOL123 Lecture Notes - Lecture 10: Resting Potential, Electrochemical Gradient, Active Transport

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