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Questions and Answers
What is the primary location for the regeneration of action potentials in myelinated axons?
What is the primary location for the regeneration of action potentials in myelinated axons?
- At the unmyelinated segments of the axon
- At the Nodes of Ranvier (correct)
- At the cell body
- At the synaptic terminals
Which advantage of saltatory conduction relates to energy efficiency?
Which advantage of saltatory conduction relates to energy efficiency?
- Faster reaction times due to increased speed of conduction
- Continuous conduction along the entire axon
- Increased myelin sheath thickness
- Reduced need for sodium removal due to localized action potentials (correct)
What are the messages sent through the axon referred to as?
What are the messages sent through the axon referred to as?
- Resting potentials
- Action potentials (correct)
- Neurotransmitters
- Membrane potentials
What is a key feature of action potentials in myelinated axons compared to unmyelinated ones?
What is a key feature of action potentials in myelinated axons compared to unmyelinated ones?
Why is the intracellular fluid negatively charged?
Why is the intracellular fluid negatively charged?
How does myelination affect the speed of action potential conduction?
How does myelination affect the speed of action potential conduction?
What charge is present in extracellular fluid?
What charge is present in extracellular fluid?
What type of conduction is characterized by the regeneration of action potentials at distinct nodes?
What type of conduction is characterized by the regeneration of action potentials at distinct nodes?
What does the term 'membrane potential' refer to?
What does the term 'membrane potential' refer to?
What happens to the membrane potential when depolarization occurs?
What happens to the membrane potential when depolarization occurs?
How is depolarization typically induced during an experiment?
How is depolarization typically induced during an experiment?
What role does the sodium-potassium transporter play in neurons?
What role does the sodium-potassium transporter play in neurons?
What is the result of applying a series of depolarizing stimuli to an axon?
What is the result of applying a series of depolarizing stimuli to an axon?
What is the term for the rapid reversal of the membrane potential in neurons?
What is the term for the rapid reversal of the membrane potential in neurons?
What occurs immediately after the depolarization phase during an action potential?
What occurs immediately after the depolarization phase during an action potential?
What is the threshold of excitation?
What is the threshold of excitation?
What primarily keeps the intracellular level of Na+ low in a neuron?
What primarily keeps the intracellular level of Na+ low in a neuron?
What causes the membrane potential to overshoot during the action potential?
What causes the membrane potential to overshoot during the action potential?
What is the primary role of ion channels in the neuronal membrane?
What is the primary role of ion channels in the neuronal membrane?
What is the effect of increased permeability of the membrane to Na+?
What is the effect of increased permeability of the membrane to Na+?
How long does the entire process of an action potential take?
How long does the entire process of an action potential take?
What primarily determines the permeability of the membrane to a specific ion at any given moment?
What primarily determines the permeability of the membrane to a specific ion at any given moment?
What is demonstrated by applying a depolarizing stimulus to the giant squid axon?
What is demonstrated by applying a depolarizing stimulus to the giant squid axon?
What happens to the strength of an action potential as it travels along the axon?
What happens to the strength of an action potential as it travels along the axon?
In what direction do action potentials travel along the axon?
In what direction do action potentials travel along the axon?
How many ions can a single sodium channel admit per second when it opens?
How many ions can a single sodium channel admit per second when it opens?
Study Notes
Neuron Communication
- Neurons communicate via action potentials, which are messages sent along the axon from the cell body to the terminal button.
- The action potential is a rapid reversal of the membrane potential, where the inside of the axon becomes positive and the outside negative.
Resting Potential
- Intracellular fluid is negatively charged due to organic anions and potassium ions (K+).
- Extracellular fluid is positively charged due to sodium ions (Na+) and chloride ions (Cl-).
- The membrane potential is the electrical charge across the membrane, representing stored electrical energy.
Maintaining Resting Potential
- A sodium-potassium transporter embedded in the cell membrane actively pumps Na+ out of the cell and K+ into it.
- The membrane is relatively impermeable to Na+, keeping the intracellular level of Na+ low.
Initiating an Action Potential
- Depolarization is achieved by applying a positive charge to the inside of the membrane, reducing the membrane potential.
- The threshold of excitation is the voltage level that triggers an action potential.
Process of Action Potential
- Increased membrane permeability to Na+ causes Na+ to rush into the cell, drastically changing the membrane potential.
- This is followed by a transient increase in membrane permeability to K+, allowing K+ to flow out of the cell.
- Ion channels, embedded within the membrane, open and close to control the flow of specific ions into and out of the cell.
- The number of open ion channels determines the membrane permeability to a particular ion at any given time.
Saltatory Conduction
- Myelination of axons allows action potentials to occur only at the unmyelinated parts of the axon (Nodes of Ranvier).
- Myelin sheath acts as an insulator, speeding up the transmission of the action potential.
- Action potentials regenerate at the Nodes of Ranvier, enabling fast and efficient transmission.
Advantages of Saltatory Conduction
- Energy efficiency: Less energy is required to maintain the action potential, as Na+ enters only at the Nodes of Ranvier.
- Speed: Conduction is faster in myelinated axons, enabling faster reaction times.
- One-way traffic: Action potentials always start at the end of the axon attached to the soma, ensuring one-way transmission.
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Description
This quiz covers the fundamental concepts of neuron communication, focusing on action potentials and resting potential. You'll explore how the membrane potential is established and maintained, as well as the mechanisms that initiate an action potential. Test your knowledge on the electrical properties of neurons and their critical role in signaling.
