BIO 311C Lecture 20: Action Potential

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yellowferret26

15 Nov 2016

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Potential energy: the energy that matter possesses as a result of its location or spatial arrangement. A separation of opposite charges = electrical potential energy = voltage. The voltage across a membrane is called membrane potential". All cells have voltages across their plasma (cell) membranes because of an unequal distribution of anions and cations on opposite sides of the membrane. Concentration gradients of k+ and na+ across the cell membrane = a chemical form of potential energy, i. e. the membrane potential. Ion channels that allow the di usion of k+ and na+ are considered to be always open because they are ungated. An electrochemical gradient results from combining two forces. Electrical the e ect of membrane potential on the movement of ions. Is the membrane potential of a neuron that is not transmitting signals ( i. e. , at rest ) Resting potential depends on ionic gradients across the plasma membrane.

Related Questions

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

40. When a protein is synthesized within the cell, this process represents a chemical reaction that is:

		explosive
		exergonic and anabolic
		exergonic and catabolic
		endergonic and anabolic
		endergonic and catabolic

39. Chemical bonds in carbohydrates (i.e., glucose) and fats, have:

		no potential or kinetic energy
		large amount of kinetic energy
		large amount of potential energy
		small amount of potential energy
		small amount of kinetic energy

38. When Na+ moves into the cell following the openning of Na+ channels, _____________________________.

		the ion charge across the membrane in the area that Na+ moves in will change.
		voltage-gated channels will close.
		an action potential will be observed.
		the cell will hyperpolarize.
		same amount of K+ ions will move out of the cell to counteract the Na+ moving into the cell.

blacklion206

Many ion channels are not normally open but must be gated oropened by some event. Which of the following is NOT a typical meansof opening ion channels?

Select one:

a. Binding of neurotransmitter to external binding site

b. Change in voltage across the membrane

c. Enzymatic reactions

d. Phosphorylation by an intracellular second messenger

Summation of local potentials can lead to a(n) _______ at theaxon hillock if the _______ is reached.

Select one:

a. equilibrium potential; threshold

b. local potential; equilibrium potential

c. action potential; equilibrium potential

d. action potential; threshold

The Na+/K+ pump helps to maintain the _______ by moving threeNa+ ions in and two K+ ions out of the cell.

Select one:

a. action potential

b. resting membrane potential

c. threshold

d. local potential

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BIO 311C Lecture 20: Action Potential

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