Neuroscience: Action Potential and Key Terms
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Questions and Answers

What is the primary function of ion channels in neurons?

  • To synthesize neurotransmitters for synaptic communication.
  • To maintain the resting membrane potential by actively pumping ions.
  • To provide structural support to the cell membrane.
  • To facilitate the rapid transmission of electrical signals. (correct)

Which process best describes the change in membrane potential during depolarization?

  • A rapid increase in membrane potential due to sodium ions entering the cell. (correct)
  • A return to the resting membrane potential following an action potential.
  • A change in membrane potential causing it to become more negative than at rest.
  • A decrease in membrane potential due to potassium ions exiting the cell.

What is the resting membrane potential of a neuron primarily caused by?

  • The presence of myelin sheaths along the axon.
  • The activity of neurotransmitters binding to postsynaptic receptors.
  • An equal distribution of sodium and potassium ions inside and outside the cell.
  • An uneven distribution of ions, with more sodium outside and more potassium inside the cell. (correct)

What is a key difference between continuous and saltatory conduction?

<p>Saltatory conduction is faster than continuous conduction, due to action potential jumping from node to node. (C)</p> Signup and view all the answers

Which of the following best describes the concept of permeability in the context of a cell membrane?

<p>The ability of the cell membrane to allow certain molecules to pass through it. (B)</p> Signup and view all the answers

What is the outcome when a neuron’s membrane potential reaches its threshold?

<p>An action potential is initiated. (A)</p> Signup and view all the answers

What is the main characteristic of the Golgi stain as used by Ramon y Cajal?

<p>It selectively stains neurons, making them visible in detail. (A)</p> Signup and view all the answers

What is the physiological effect during repolarization?

<p>Potassium channels open, causing an efflux of positive ions. (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of a stereotypical neuron as described in the text?

<p>Generates action potentials solely in myelinated regions. (A)</p> Signup and view all the answers

What is the primary reason for inserting a microelectrode into a neuron?

<p>To record the neuron's resting membrane potential. (B)</p> Signup and view all the answers

What is the state of ion concentration in a neuron at rest?

<p>Sodium and calcium ions are more concentrated outside the cell, while potassium ions are more concentrated inside. (C)</p> Signup and view all the answers

The sodium-potassium pump of a neuron helps establish action potentials by?

<p>Moving sodium out of the cell and potassium into it. (C)</p> Signup and view all the answers

How does the influx of sodium (Na+) ions at one location of an axon lead to an action potential at adjacent locations?

<p>The massive Na+ influx creates a wave of positive current that triggers Na+ influx at adjacent locations. (A)</p> Signup and view all the answers

What is the role of the nodes of Ranvier in myelinated axons during action potential propagation?

<p>They are the locations where the wave of current triggers a new action potential. (B)</p> Signup and view all the answers

Why does the current flow back up the axon not trigger an action potential at the original node of Ranvier?

<p>The refractory period is the time between two action potentials, the node of ranvier is still in refractory (C)</p> Signup and view all the answers

What factor(s) increase the conduction velocity of action potentials?

<p>Increased axon diameter and myelination. (A)</p> Signup and view all the answers

Flashcards

Conductance

The process of transmitting an electrical signal along the length of a neuron's axon. This occurs when an action potential is fired.

Permeability

The ability of a cell membrane to allow certain molecules to pass through it.

Ion Channel

A protein embedded in a cell membrane that allows specific ions to pass through. They are responsible for the transmission of electrical signals in the nervous system. They are fast-acting and selective.

Resting Membrane Potential

The electrical charge difference across a neuron's membrane when it's not actively sending signals. It's caused by an uneven distribution of ions inside and outside the cell. This uneven distribution is due to charged ions like sodium (Na+) being concentrated outside the cell while potassium (K+) ions are concentrated inside the cell.

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Action Potential

An electrical impulse that travels down an axon to send signals. It consists of three stages: depolarization, repolarization, and hyperpolarization.

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Action potential Threshold

The membrane potential level (electrical activity level) that must be reached to initiate an action potential. It's an all-or-nothing phenomenon.

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EPSP (Excitatory Postsynaptic Potential)

A postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential.

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IPSP (Inhibitory Postsynaptic Potential)

A postsynaptic potential that makes the postsynaptic neuron less likely to fire an action potential.

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Neuron

A specialized cell responsible for transmitting information throughout the nervous system.

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Axon

The long, slender projection of a neuron that carries nerve impulses away from the cell body.

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Dendrite

The branching extensions of a neuron that receive signals from other neurons.

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Synapse

The junction between the axon of one neuron and the dendrite or cell body of another neuron.

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Resting Potential

The difference in electrical charge between the inside and outside of a neuron at rest.

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Myelin Sheath

A fatty substance that insulates axons, increasing the speed of nerve impulse transmission.

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Neural Integration

The process by which neurons integrate incoming signals from multiple sources and generate an appropriate output.

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Study Notes

Key Terms

  • Conductance: The process of transmitting an electrical signal along a neuron's axon, triggered by an action potential.
  • Permeability: A cell membrane's ability to allow certain molecules to pass through.
  • Ion channel: A protein embedded in a cell membrane that allows specific ions to pass through, crucial for transmitting electrical signals.

Action Potential

  • Action Potential: An electrical impulse that travels along an axon to transmit signals.
  • Depolarization: A phase where sodium channels open, leading to a rapid increase in membrane potential, becoming more positive.
  • Repolarization: A phase where potassium channels open, causing a return to the resting membrane potential.
  • Hyperpolarization: A phase where the membrane potential becomes more negative than the resting potential.
  • Threshold: The membrane potential level (electrical activity level) that must be reached to initiate an action potential. It's an "all-or-none" phenomenon.

Ion Distribution

  • Ion distribution: Uneven distribution of ions (sodium, calcium, chloride, potassium) across the membrane is essential for creating a resting membrane potential.
  • Resting membrane potential: The electrical charge difference across a neuron's membrane when it's not actively sending signals, typically around -70mV.

Action Potential Propagation

  • Continuous Conduction: Slow propagation of action potentials along unmyelinated axons.
  • Saltatory Conduction: Rapid transmission of action potentials along myelinated axons, "jumping" between nodes of Ranvier.
  • Myelin sheath: Insulating layer around some axons, increasing the speed of action potential propagation.
  • Nodes of Ranvier: Gaps in the myelin sheath where action potentials are regenerated, crucial for saltatory conduction.

Neuron Function

  • Neurons: Discrete cells, transmitting signals through electrical and chemical processes.
  • Neurotransmitters: Chemical messengers enabling communication between neurons.
  • EPSPs (Excitatory Postsynaptic Potentials) are small depolarizing signals at synapses
  • IPSPs (Inhibitory Postsynaptic Potentials) are small hyperpolarizing signals at synapses
  • Spatial Summation: Combining simultaneous EPSPs from multiple synapses.
  • Temporal Summation: Adding up EPSPs from one synapse over a short time.

Neuron Types and Function

  • Neurons have varying shapes and sizes.
  • Different receptors determine neuron function.
  • Glutamate is a primary excitatory neurotransmitter; GABA is inhibitory.
  • Coincidence detectors: neurons that fire when multiple signals reach them at the same time or very close.

Neurotransmitters

  • Major Neurotransmitters: Specific neurotransmitters perform different roles in the nervous system. Examples include glutamate, GABA, dopamine, serotonin, acetylcholine
  • Neuropeptides: Proteins that act as neurotransmitters and have widespread, often regulating, effects within the nervous system.

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Note Jan 26, 2025 PDF

Description

Test your understanding of the key terms and concepts related to action potentials in neuroscience. Explore terms like conductance, permeability, and the various phases of action potential from depolarization to hyperpolarization. This quiz will challenge your knowledge of neuronal signaling.

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