Chapter 6 Resting Membrane Potential (RMP) What is the Resting Membrane Potential (RMP)? ELECTRIC POTENTIAL – separation of opposite charges between 2 points. (“Has the potential to do electrical work if allowed to come together!”) vs. large potential difference small potential difference Magnitude of charge separation = potential difference ** measured in volts (1 Volt
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cell B‚ which cell has the larger resting membrane potential? Explain. If the permeability to K is higher in A than in B‚ then the resting membrane potential (rmp) will be closer to the equilibrium potential in cell A‚ which means the rmp will be more negative in cell A than in cell B; or in other words‚ the potential difference will be LARGER in cell A. 2. Predict the effect of a reduced extracellular concentration of Na+ on the magnitude of the action potential in an electrically excitable cell
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The Nervous System: Membrane Potential 1. Record the intracellular and extracellular concentrations of the following ions (mM/L): Intracellular Extracellular Sodium (Na+) Potassium (K+) Chloride (Cl–) 2. Excitable cells‚ like neurons‚ are more permeable to ___________ than to ___________. 3. How would the following alterations affect the membrane permeability to K+? Use arrows to indicate the change in permeability. a. An increase in the number of passive K+ channels
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Resting membrane potentials Definition: Large nerve fibers when not transmitting nerve signals is about 90 millivolt. That is‚ the potential inside the fiber is 90 millivolts more negative than the potential in the extracellular fluid on the outside of the fiber. The Na+-k+ pump also causes large concentration gradients for sodium and potassium across the resting nerve membrane. These gradients are the following: Sodium ( outside): 142 mEq/L Sodium ( inside): 14 mEq/L Potassium ( outside):
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unit of the nervous system. These neurons work together with other excitable cells to produce action potentials when they receive electrical or chemical stimuli. Action potentials can be thought of as an “all-or-nothing” event and occur as a large-scale depolarization when sodium and other positive ions rapidly enter the neuron through membrane channel proteins. Once initiated‚ action potentials travel down the length of the axon and when it reaches the end a neurotransmitter is released into the
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Resting potential is created by a transport protein called the sodium-potassium pump. Resting potential occurs when ions are distributed unequally on the inside and outside of cells‚ and when cell membranes are selectively permeable to different ions. K+ is particularly important for the resting potential. The membrane is highly permeable to K+. In addition‚ the inside of the cell has a high concentration of K+ and the outside of the cell has a low concentration of K+. K+ will naturally diffuse
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more concentration of K+. The membrane is permeable to a particular ion‚ that ion will diffuse down its concentration gradient from a region of higher concentration to a region of lower concentration. 2. Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value. How well did the results compare with your prediction? Your answer: Because outside has more K+‚ the rate of diffusion is less. The resting membrane potential will become less negative. 3
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Exercise 3: Neurophysiology of Nerve Impulses: Activity 1: The Resting Membrane Potential Lab Report 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: a. 150 mM 2. What is the approximate concentration of K+ outside a cell (extracellular concentration)? You correctly answered: b. 5 mM 3. What is the approximate concentration of Na+ inside
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into the bloodstream of the patient‚ the K+ gradient across the membrane is reduced. This results in depolarization where cells generate an action potential. Voltage-gated Na+ channels open in response to depolarization and close by inactivation for a refractory period and remain closed until repolarization. In this new setting‚ less K+ leaks out of the intracellular space and the cell is unable to return to its resting membrane potential (ie. The cell stays slightly depolarized) as the voltage-gated
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cell is at rest it has a resting potential of -90mV. The K+ is all located inside the cell‚ the Na+ is located outside of the cell and the Ca2+ is located inside the sarcoplasmic reticulum. All leak channels and pumps are closed at this point. Muscle Cell stimulated by Acetylcholine: A motor neuron releases Acetylcholine which diffuses toward the muscle cell across the neuromuscular junction. As the Acetylcholine binds to a receptor on the muscle cell membrane‚ it signals the sodium
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