Podcast
Questions and Answers
The difference in charge across the membrane induces a voltage difference and is called _______________
The difference in charge across the membrane induces a voltage difference and is called _______________
Nernst equilibrium potential
Neurons can produce a spike of electrical activity called _______________
Neurons can produce a spike of electrical activity called _______________
action potential
The electrical burst in a neuron travels along the neuron’s ___________ to its ___________ where it passes the signals to other neurons.
The electrical burst in a neuron travels along the neuron’s ___________ to its ___________ where it passes the signals to other neurons.
axon, axon terminal
What is the primary principle that causes ions to flow across the neuron's membrane?
What is the primary principle that causes ions to flow across the neuron's membrane?
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What is the pump that pumps three sodium ions out of the neuron for every two potassium ions pumped in?
What is the pump that pumps three sodium ions out of the neuron for every two potassium ions pumped in?
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What is the electrical gradient that occurs when more potassium ions diffuse out, making the outside of the cell more positive and the inside more negative?
What is the electrical gradient that occurs when more potassium ions diffuse out, making the outside of the cell more positive and the inside more negative?
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At what potential does the Equilibrium position occur for potassium ions if the cell is permeable to potassium ions?
At what potential does the Equilibrium position occur for potassium ions if the cell is permeable to potassium ions?
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What is the model that is based on the nonlinear interaction between membrane potential and the opening and closing of sodium and potassium ion channels?
What is the model that is based on the nonlinear interaction between membrane potential and the opening and closing of sodium and potassium ion channels?
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Study Notes
Cell Resting State
- A cell at rest has a higher concentration of potassium ions (K+) inside the cell and a higher concentration of sodium ions (Na+) outside the cell.
- This concentration gradient creates a negative net charge within the cell, maintained by a voltage gradient.
Depolarization and Repolarization
- When a cell becomes depolarized, sodium ions (Na+) enter the cell, making the charge within the cell more positive.
- When a cell repolarizes, potassium ions (K+) leave the cell, and the charge within the cell returns to a negative state.
Ion Flow and Resting Potential
- Even when the cell is at rest, potassium ions (K+) still flow out of the cell, causing a slight undershoot or hyperpolarization of the resting potential.
- The sodium-potassium pump and leakage channels compensate for this undershoot, re-establishing the initial resting potential.
Ions and Electric Charge
- An ion is an atom or group of atoms with an electric charge, which occurs when the number of electrons does not match the number of protons.
- Positive ions are called cations, while negative ions are called anions.
- Common ions in the body include sodium, potassium, calcium, chloride, and bicarbonate.
Neuron Electrical Activity
- The difference in charge across the membrane induces a voltage difference, known as the Nernst equilibrium potential.
- Neurons can produce a spike of electrical activity called an action potential.
- The electrical burst in a neuron travels along the axon to the terminal, where it passes signals to other neurons.
Nernst Equilibrium Potential
- The Nernst equation can estimate the resting potential of a neuron based on the concentration gradients of different ions.
- For example, if a cell has only potassium channels, the concentration gradient favors potassium ions to exit the cell, making the outside more positive and the inside more negative.
Diffusion Potential
- As potassium ions diffuse out of the cell, they carry a positive charge with them, making the outside of the cell more positive and the inside more negative.
- This electrical gradient, known as the diffusion potential, blocks the further exit of potassium ions despite the existing concentration gradient.
Hodgkin and Huxley Model
- The Hodgkin-Huxley Model describes the interaction between membrane potential (voltage) and the opening and closing of sodium (Na+) and potassium (K+) ion channels.
- Both Na+ and K+ ion channels are voltage-dependent, and their opening and closing changes with the membrane potential.
- The model acknowledges the role of ionic sodium and potassium currents, as well as leak currents, through the use of conductance terms (gating variables).
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Description
Understand the ionic movements and charge changes within a cell during depolarization and repolarization. Learn how sodium and potassium ions affect the cell's net charge and voltage gradient.
