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Questions and Answers
What is the resting membrane potential typically for a neuron?
What is the resting membrane potential typically for a neuron?
- -20 mV
- -40 mV
- -90 mV
- -60 mV (correct)
What is the main role of K+ in generating membrane potential?
What is the main role of K+ in generating membrane potential?
- Stabilizing the resting membrane potential
- Increasing the permeability of the membrane to Na+ ions
- Balancing the (+) charges of intracellular cations (correct)
- Balancing the (-) charges of intracellular anions
What is the function of the ATP-driven sodium-potassium pump?
What is the function of the ATP-driven sodium-potassium pump?
- Generating membrane potential
- Increasing the permeability of the membrane to Cl- ions
- Maintaining the concentration gradients of Na+ and K+ (correct)
- Ejecting three K+ from the cell
What contributes to the cell being more negative inside?
What contributes to the cell being more negative inside?
What is the main reason for the separation of (+) and (-) charges across the membrane?
What is the main reason for the separation of (+) and (-) charges across the membrane?
What is the electrical property of neurons and synapse structure?
What is the electrical property of neurons and synapse structure?
What is the role of the leakage ion channels in the membrane?
What is the role of the leakage ion channels in the membrane?
What is the unit of measurement for potential energy in the context of the resting membrane potential?
What is the unit of measurement for potential energy in the context of the resting membrane potential?
What neurotransmitter is involved in reward, motivation, and motor control?
What neurotransmitter is involved in reward, motivation, and motor control?
Which neurotransmitter is mainly inhibitory and produces a calming effect?
Which neurotransmitter is mainly inhibitory and produces a calming effect?
What neurotransmitter is linked to pain control and pleasure?
What neurotransmitter is linked to pain control and pleasure?
Which neurotransmitter is involved in controlling alertness and arousal?
Which neurotransmitter is involved in controlling alertness and arousal?
What neurotransmitter affects hunger, sleep, arousal, and mood?
What neurotransmitter affects hunger, sleep, arousal, and mood?
Which neurotransmitter activates the sympathetic nervous system by increasing heart rate and enlarging pupils?
Which neurotransmitter activates the sympathetic nervous system by increasing heart rate and enlarging pupils?
What neurotransmitter is a major excitatory neurotransmitter involved in information transmission throughout the brain?
What neurotransmitter is a major excitatory neurotransmitter involved in information transmission throughout the brain?
Which neurotransmitter is released in excess during allergic reactions, causing swelling and inflammation of tissues?
Which neurotransmitter is released in excess during allergic reactions, causing swelling and inflammation of tissues?
Which cranial nerve controls most facial expressions and secretion of tears and saliva?
Which cranial nerve controls most facial expressions and secretion of tears and saliva?
Which cranial nerve is responsible for innervating the superior oblique muscle of the eye?
Which cranial nerve is responsible for innervating the superior oblique muscle of the eye?
Which cranial nerve is associated with the sense of smell?
Which cranial nerve is associated with the sense of smell?
Which cranial nerve is responsible for controlling the trapezius and sternocleidomastoid muscles, as well as swallowing movements?
Which cranial nerve is responsible for controlling the trapezius and sternocleidomastoid muscles, as well as swallowing movements?
What is the result of excessive K+ efflux following action potential (AP)?
What is the result of excessive K+ efflux following action potential (AP)?
What is the threshold for action potential (AP)?
What is the threshold for action potential (AP)?
How is stimulus intensity coded?
How is stimulus intensity coded?
What is the function of absolute refractory period?
What is the function of absolute refractory period?
What is the effect of myelin sheath on the rate of action potential (AP) propagation?
What is the effect of myelin sheath on the rate of action potential (AP) propagation?
What is the role of the relative refractory period?
What is the role of the relative refractory period?
How do nerve fibers transmit impulses where speed is essential?
How do nerve fibers transmit impulses where speed is essential?
What is the role of all-or-none phenomenon in action potential (AP)?
What is the role of all-or-none phenomenon in action potential (AP)?
What is the range of impulse transmission speed in nerve fibers?
What is the range of impulse transmission speed in nerve fibers?
What is the function of the after-hyperpolarization (undershoot)?
What is the function of the after-hyperpolarization (undershoot)?
What is the effect of axon diameter on the rate of impulse propagation?
What is the effect of axon diameter on the rate of impulse propagation?
What is the role of salutatory conduction?
What is the role of salutatory conduction?
What is the main characteristic of graded potentials?
What is the main characteristic of graded potentials?
What triggers the opening of gated ion channels in response to graded potentials?
What triggers the opening of gated ion channels in response to graded potentials?
What occurs when neurotransmitters released by another neuron influence a neuron beyond the synapse?
What occurs when neurotransmitters released by another neuron influence a neuron beyond the synapse?
What is the process by which graded potentials add together, resulting in larger depolarizing or hyperpolarizing potentials?
What is the process by which graded potentials add together, resulting in larger depolarizing or hyperpolarizing potentials?
What is the main event in synapse structure involving the arrival of an action potential at the axon terminal?
What is the main event in synapse structure involving the arrival of an action potential at the axon terminal?
What is the total amplitude of action potentials?
What is the total amplitude of action potentials?
Where do neurons and muscle cells typically generate action potentials?
Where do neurons and muscle cells typically generate action potentials?
What is the state of gated Na+ and K+ channels during the resting state of a neuron?
What is the state of gated Na+ and K+ channels during the resting state of a neuron?
What characterizes the depolarizing phase of an action potential?
What characterizes the depolarizing phase of an action potential?
What characterizes the repolarizing phase of an action potential?
What characterizes the repolarizing phase of an action potential?
What occurs during hyperpolarization following an action potential?
What occurs during hyperpolarization following an action potential?
What is the critical mechanism for transmitting signals over long distances in neurons?
What is the critical mechanism for transmitting signals over long distances in neurons?
Study Notes
Neural Action Potential and Propagation
- After-hyperpolarization (undershoot) results from excessive K+ efflux following action potential (AP)
- AP must be propagated along axon’s entire length for neuron signaling
- AP self-propagates at constant velocity on unmyelinated axons (salutatory conduction on myelinated axons)
- Threshold for AP is when depolarization reaches -55 to -50 mV
- All-or-none phenomenon: AP either happens completely or not at all
- Stimulus intensity is coded by frequency of AP, not by amplitude of individual APs
- Absolute refractory period: from opening of Na+ channels until reset, enforces one-way transmission
- Relative refractory period: following absolute refractory period, axon’s threshold for AP generation is substantially elevated
- Nerve fibers transmit impulses more rapidly (100 m/s or more) where speed is essential
- Axon diameter and myelination affect rate of impulse propagation
- Myelin sheath dramatically increases rate of AP propagation
- Electrical signals rely on four types of ion channels: leakage, ligand-gated, mechanically gated, and voltage-gated
Neurophysiology: Graded Potentials, Synapse Structure, and Action Potentials
- Graded potentials are short-lived, localized changes in membrane potential caused by stimuli, resulting in depolarization or hyperpolarization.
- Graded potentials vary in magnitude with the strength of the stimulus and trigger gated ion channels to open.
- Postsynaptic potentials occur when neurotransmitters released by another neuron influence a neuron beyond the synapse.
- Summation is the process by which graded potentials add together, resulting in larger depolarizing or hyperpolarizing potentials.
- Synapse structure involves the arrival of an action potential at the axon terminal, followed by the release of neurotransmitters and their effects on the postsynaptic membrane.
- Action potentials are brief reversals of membrane potential with a total amplitude of around 100 mV and do not decrease in strength with distance.
- Neurons and muscle cells can generate action potentials, typically in axons, and involve depolarization, repolarization, and often hyperpolarization.
- The resting state of a neuron involves closed gated Na+ and K+ channels, with leakage channels open.
- The depolarizing phase of an action potential involves the opening of voltage-gated Na+ channels, allowing Na+ to rush into the cell and depolarize the membrane.
- The repolarizing phase of an action potential involves the inactivation of Na+ channels and the opening of K+ channels, allowing K+ to rush out of the cell and contribute to repolarization.
- Hyperpolarization occurs as some K+ channels remain open, and Na+ channels reset, temporarily making the membrane potential more negative than the resting level.
- The action potential is a critical mechanism for transmitting signals over long distances and involves the opening and closing of voltage-gated channels in response to changes in membrane potential.
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Description
Test your knowledge of neural action potential and propagation with this quiz. Explore topics such as after-hyperpolarization, AP propagation, threshold for AP, refractory periods, myelination, and ion channels. Also, dive into graded potentials, synapse structure, neurotransmitters, summation, and the phases of action potentials.
