Podcast
Questions and Answers
What is the equilibrium potential calculated using the Nernst equation directly dependent on?
What is the equilibrium potential calculated using the Nernst equation directly dependent on?
Which value can be simplified to 61.5 when calculating the equilibrium potential at normal body temperature?
Which value can be simplified to 61.5 when calculating the equilibrium potential at normal body temperature?
Which neuroglia are primarily responsible for myelinating axons in the peripheral nervous system?
Which neuroglia are primarily responsible for myelinating axons in the peripheral nervous system?
What will happen when chloride ions enter a resting neuron?
What will happen when chloride ions enter a resting neuron?
Signup and view all the answers
Which of the following ions does not contribute to the Nernst potential equation for a monovalent ion?
Which of the following ions does not contribute to the Nernst potential equation for a monovalent ion?
Signup and view all the answers
Which of the following values is NOT necessary in calculating the equilibrium potential using the Nernst equation?
Which of the following values is NOT necessary in calculating the equilibrium potential using the Nernst equation?
Signup and view all the answers
What type of neuron carries signals exclusively toward the brain?
What type of neuron carries signals exclusively toward the brain?
Signup and view all the answers
What component of the neuron is primarily responsible for sending electrical signals over long distances?
What component of the neuron is primarily responsible for sending electrical signals over long distances?
Signup and view all the answers
What is the primary ion responsible for the depolarization phase of an action potential?
What is the primary ion responsible for the depolarization phase of an action potential?
Signup and view all the answers
During the repolarization phase of an action potential, which ion moves out of the neuron?
During the repolarization phase of an action potential, which ion moves out of the neuron?
Signup and view all the answers
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?
Signup and view all the answers
Which of the following statements about action potentials is true?
Which of the following statements about action potentials is true?
Signup and view all the answers
Which of the following best describes the role of voltage-gated sodium channels during the action potential?
Which of the following best describes the role of voltage-gated sodium channels during the action potential?
Signup and view all the answers
What is the primary reason for the refractory period following an action potential?
What is the primary reason for the refractory period following an action potential?
Signup and view all the answers
Which of the following factors does NOT affect the conduction velocity of an action potential along an axon?
Which of the following factors does NOT affect the conduction velocity of an action potential along an axon?
Signup and view all the answers
During the after potential or hyperpolarization phase of an action potential, which of the following occurs?
During the after potential or hyperpolarization phase of an action potential, which of the following occurs?
Signup and view all the answers
What primarily contributes to the resting membrane potential (RMP)?
What primarily contributes to the resting membrane potential (RMP)?
Signup and view all the answers
What drives the movement of ions across the membrane?
What drives the movement of ions across the membrane?
Signup and view all the answers
How does the movement of K+ ions from the intracellular region to the extracellular region affect the cell?
How does the movement of K+ ions from the intracellular region to the extracellular region affect the cell?
Signup and view all the answers
What is the role of the leak channel in ion movement?
What is the role of the leak channel in ion movement?
Signup and view all the answers
What eventually opposes the movement of K+ ions out of the cell?
What eventually opposes the movement of K+ ions out of the cell?
Signup and view all the answers
Which statement best compares conductance and permeability?
Which statement best compares conductance and permeability?
Signup and view all the answers
What is likely to happen if the electrostatic gradient inside the cell becomes strong enough?
What is likely to happen if the electrostatic gradient inside the cell becomes strong enough?
Signup and view all the answers
What maintains the concentration gradients of sodium and potassium ions across the cell membrane?
What maintains the concentration gradients of sodium and potassium ions across the cell membrane?
Signup and view all the answers
Study Notes
Lecture 4: Membrane Potentials Review
- Sodium (Na+) and potassium (K+) play a dominant role in resting membrane potential (RMP).
- Intracellular proteins and organic phosphates, which cannot cross the cell membrane, also contribute to RMP.
- Understanding equilibrium potentials, permeability, and ion pumps is crucial to comprehending RMP generation and its negative value.
How and Why Ions Move: Gradients
- The difference in ion concentration (gradient) across the membrane drives ion movement.
- This gradient is maintained by primary or secondary active transport, creating a force for ion movement across the membrane.
- Ion channels (leak channels) allow ions to pass through the membrane, moving down their concentration gradient (high to low). For example, K+ moves from inside to outside the cell.
How and Why Ions Move: Charge
- Positive and negative ions tend to pair up in solution (opposites attract).
- Cation movement from inside to outside a cell leaves behind a negative anion, making the inside more negative and the outside more positive.
- This electrostatic gradient builds up over time.
- The negative charge inside the cell exerts a force opposing the outward movement of positively charged ions (like K+) down their concentration gradient.
- Equilibrium potential is reached when the electrostatic force equals the concentration gradient, stopping ion movement. This is calculated by the Nernst equation.
Equilibrium Potential
- The Nernst equation calculates equilibrium potential (Vm):
- Vm = RT/zF * ln([ion outside the cell]/[ion inside the cell])
- R = gas constant (8.314472 J. K⁻¹)
- T = temperature (Kelvin)
- F = Faraday's constant (9.65 x 10⁴ C mol⁻¹)
- Z = ion charge (1 for monovalent ions like K+, 2 for divalent ions like Ca²⁺)
- Simplifying the equation at normal body temperature (37°C): RT/F ≈ 61.5
- Simplifying the equation at room temperature (18°C): RT/F ≈ 58
RMP in Different Cells and Its Roles
- Resting membrane potential (RMP) varies among different cell types.
- A table (not included in the text provided) illustrates different functions (e.g., circadian rhythm, biological sensing, or contractility) and associated cell types (neuros, fibroblasts, vascular smooth muscle cells) that are regulated by RMP.
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 specific to K+
The entry of chloride ions into resting neurons:
- Causes a hyperpolarization
Which of the following values is unnecessary when finding the equilibrium potential of an ion using the Nernst equation?
- The 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 the 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 afterpotential or hyperpolarization phase of an action potential, which of the following occurs?
- Voltage-gated potassium channels remain open longer than necessary.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers key concepts related to membrane potentials, focusing on the roles of sodium and potassium ions in resting membrane potential. It explores the mechanisms of ion movement across membranes, including gradients and ion channels, and their importance in cellular physiology. Perfect for students looking to deepen their understanding of bioelectric processes in cells.
