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Questions and Answers
The Na+ concentration is higher inside the cell compared to outside.
The Na+ concentration is higher inside the cell compared to outside.
False
The K+ concentration is higher inside the cell compared to outside.
The K+ concentration is higher inside the cell compared to outside.
True
The total positive ions inside and outside the cell are 160 mmol/L.
The total positive ions inside and outside the cell are 160 mmol/L.
False
The RMP of a typical neuron is +70 mV.
The RMP of a typical neuron is +70 mV.
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The resting potential is a unique property only found in neurons.
The resting potential is a unique property only found in neurons.
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The extracellular potential is defined as -70 V in the custom definition of RMP.
The extracellular potential is defined as -70 V in the custom definition of RMP.
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Depolarization is caused by the net flow of positive charges into the cell.
Depolarization is caused by the net flow of positive charges into the cell.
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Repolarization is when the cell experiences an increase in voltage due to the influx of potassium (K+) ions.
Repolarization is when the cell experiences an increase in voltage due to the influx of potassium (K+) ions.
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Hyperpolarization occurs due to the net flow of positive charges into the cell.
Hyperpolarization occurs due to the net flow of positive charges into the cell.
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At the threshold potential, the cell membrane opens up allowing Na+ transport.
At the threshold potential, the cell membrane opens up allowing Na+ transport.
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The resting potential of the membrane is +70 mV.
The resting potential of the membrane is +70 mV.
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Action potential propagation involves the unusual activity of electrical signal degradation.
Action potential propagation involves the unusual activity of electrical signal degradation.
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Graded potentials are major changes in membrane potential due to the binding of neurotransmitters.
Graded potentials are major changes in membrane potential due to the binding of neurotransmitters.
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Action potentials have relatively large depolarizations by 50–60 mV above the resting value of −70 mV.
Action potentials have relatively large depolarizations by 50–60 mV above the resting value of −70 mV.
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Successive graded potentials can add to one another and propagate long distances along the membrane.
Successive graded potentials can add to one another and propagate long distances along the membrane.
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Action potentials are qualitatively similar to graded potentials in every aspect.
Action potentials are qualitatively similar to graded potentials in every aspect.
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The resting membrane potential is approximately -90 mV.
The resting membrane potential is approximately -90 mV.
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Cell membranes allow ion leakage through the membrane due to the binding of neurotransmitters.
Cell membranes allow ion leakage through the membrane due to the binding of neurotransmitters.
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Study Notes
Ion Distribution Across the Cell Membrane
- There is a higher concentration of Na+ (145 mmol/L) outside the cell than inside (14 mmol/L)
- There is a higher concentration of K+ (140 mmol/L) inside the cell than outside (5 mmol/L)
- The total concentration of positive ions inside and outside the cell is 165 mmol/L
Resting Membrane Potential (RMP)
- The RMP is the voltage across a cell membrane during the resting stage
- In neuromuscular tissues, the RMP of a typical neuron is about −70 mV, with the interior of the cell negative in charge to the outside
- The basis for the RMP is the unequal distribution of ions, particularly K+ and Na+, on either side of the plasma membrane
Action Potential
- The propagation of an electrical signal would constitute unusual activity
- Depolarization is due to the net flow of positive charges into the cell or negative charges to regions outside the cell
- Repolarization is a stage of an action potential in which the cell experiences a decrease in voltage due to the efflux of potassium (K+) ions along its electrochemical gradient
- Hyperpolarization is due to the net flow of negative charges into the cell or positive charges to outside the cell, resulting in a polarized state
Types of Cell Membrane Excitations
- There are two types of axon excitations: graded potentials and action potentials
- Graded potentials are minor perturbations in the membrane potential due to the binding of neurotransmitters, the stimulation of sensory reception, or spontaneous ion leakage through the cell membrane
- Successive graded potentials can add to one another, but they only propagate short distances along the membrane before decaying
- Action potentials are qualitatively different from graded potentials, with relatively large depolarizations above the resting value of −70 mV to a threshold of about −55 mV
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Description
Test your knowledge on the resting membrane potential (RMP) of cells and the distribution of sodium (Na+) and potassium (K+) ions inside and outside the cell. Explore the relationship between ion concentration gradients and the RMP in neuromuscular tissues.
