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Questions and Answers
Which ion primarily contributes to the negativity of the resting membrane potential (RMP) when moving from inside to outside the cell?
Which ion primarily contributes to the negativity of the resting membrane potential (RMP) when moving from inside to outside the cell?
What primarily maintains the concentration gradient of ions across the cell membrane?
What primarily maintains the concentration gradient of ions across the cell membrane?
How does the movement of K+ ions affect the electrostatic charge inside the cell?
How does the movement of K+ ions affect the electrostatic charge inside the cell?
What role do negatively charged intracellular proteins and organic phosphates play in the resting membrane potential?
What role do negatively charged intracellular proteins and organic phosphates play in the resting membrane potential?
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What impact does the concentration gradient have on ion movement across the membrane?
What impact does the concentration gradient have on ion movement across the membrane?
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What is the relationship between permeability and conductance in the context of ion movement?
What is the relationship between permeability and conductance in the context of ion movement?
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What happens to ion movement when the negative electrostatic charge inside the cell balances the concentration gradient force?
What happens to ion movement when the negative electrostatic charge inside the cell balances the concentration gradient force?
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What is the primary factor affecting the value of the equilibrium potential calculated using the Nernst equation?
What is the primary factor affecting the value of the equilibrium potential calculated using the Nernst equation?
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Which equation is key for calculating the equilibrium potential for a specific ion?
Which equation is key for calculating the equilibrium potential for a specific ion?
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At what temperature does the simplification RT/F become 61.5?
At what temperature does the simplification RT/F become 61.5?
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What is the primary function of Schwann cells in the peripheral nervous system?
What is the primary function of Schwann cells in the peripheral nervous system?
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What does the term 'membrane equilibrium potential' refer to?
What does the term 'membrane equilibrium potential' refer to?
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Which ion's equilibrium potential is described as the threshold for opening voltage gated K+ channels?
Which ion's equilibrium potential is described as the threshold for opening voltage gated K+ channels?
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Which of the following provides the main mechanism for maintaining ionic gradients across membranes?
Which of the following provides the main mechanism for maintaining ionic gradients across membranes?
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What occurs when chloride ions enter a resting neuron?
What occurs when chloride ions enter a resting neuron?
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Which value is not needed when calculating the equilibrium potential using the Nernst equation?
Which value is not needed when calculating the equilibrium potential using the Nernst equation?
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What is the effect of temperature on the Nernst equation simplifications?
What is the effect of temperature on the Nernst equation simplifications?
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Which ion is primarily responsible for initiating the depolarization phase of an action potential?
Which ion is primarily responsible for initiating the depolarization phase of an action potential?
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What is the typical threshold potential that must be reached for an action potential to be initiated?
What is the typical threshold potential that must be reached for an action potential to be initiated?
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During the repolarization phase of an action potential, which ion primarily leaves the neuron?
During the repolarization phase of an action potential, which ion primarily leaves the neuron?
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Which of the following statements accurately describes the action potential process?
Which of the following statements accurately describes the action potential process?
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Which factor does NOT have an influential role on the conduction velocity of an action potential along an axon?
Which factor does NOT have an influential role on the conduction velocity of an action potential along an axon?
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Study Notes
Lecture 4: Membrane Potentials Review
- Sodium (Na+) and potassium (K+) play a crucial role in resting membrane potential (RMP).
- Intracellular proteins and organic phosphates contribute to the negative charge inside the cell.
- Understanding RMP generation requires understanding equilibrium potentials, membrane permeability, and ion pumps.
How and Why Ions Move? Gradients
- The difference in ion concentration (gradient) across the membrane drives ion movement.
- This gradient is maintained using active transport (primary or secondary).
- Ion channels (leak channels) facilitate ion movement down their concentration gradient. Potassium (K+) moves from inside the cell to outside.
How and Why Ions Move? Charge
- Positive and negative ions tend to pair up in solutions.
- The movement of a cation (e.g., K+) causes a buildup of negative charge inside the cell and positive charge outside.
- This electrical gradient opposes the concentration gradient of ions.
- Equilibrium potential is when the electrical and concentration forces are balanced. Calculated using the Nernst equation.
Equilibrium Potential
- Calculated using the Nernst equation: Vm = RT/zF * ln([ion outside the cell] / [ion inside the cell]).
- R = gas constant; T = temperature (Kelvin); F = Faraday's constant; Z = ion charge.
- Simplifies to 61.5 mV at 37°C (normal body temperature) and 58 mV at 18°C (room temperature).
RMP in Different Cells
- Resting membrane potential (RMP) values vary across different cell types.
- A table (provided in the images) shows various cell types and their corresponding RMP values.
- RMP plays a role in various cellular functions, such as circadian rhythm, sensing, contractility, hearing, and volume control.
What kind of Neurons carry signals exclusively towards the brain?
- Sensory neurons.
The part of the neuron that sends electrical signals over large distances is the:
- Axon.
Which neuroglia are responsible for forming the myelin sheath around axons in the peripheral nervous system?
- Schwann cells.
Ionic gradients across membranes are maintained by:
- Sodium/potassium pumps.
The Nernst potential for potassium is:
- The equilibrium potential for K+.
The entry of chloride ions into resting neuron
- Will cause a hyperpolarization.
Which of the following values is unnecessary when finding the equilibrium potential of an ion using the Nernst equation?
- Permeability of the ion channel.
What is the primary ion responsible for the depolarization phase of an action potential?
- Sodium (Na+).
During the repolarization phase of an action potential, which ion moves out of the neuron?
- Potassium (K+).
What is the typical threshold potential that must be reached for an action potential to be initiated?
- -55 mV.
Which of the following statements about action potentials is true?
- Action potentials are all-or-nothing events.
Which of the following best describes the role of voltage-gated sodium channels during the action potential?
- They open in response to depolarization and allow sodium ions to enter the cell.
What is the primary reason for the refractory period following an action potential?
- To prevent backward propagation of the action potential.
Which of the following factors does NOT affect the conduction velocity of an action potential along an axon?
- Length of the axon.
During the after potential or hyperpolarization phase of an action potential, which of the following occurs?
- Voltage-gated potassium channels remain open longer than necessary.
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Description
This quiz reviews key concepts of membrane potentials, focusing on the roles of sodium and potassium in generating resting membrane potential. It also explores ion movement driven by concentration and electrical gradients, and the impact of ion channels and pumps on these processes.
