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What is the resting membrane potential of an axon at rest?
What is the resting membrane potential of an axon at rest?
What is the critical threshold that needs to be reached to trigger an action potential in an axon?
What is the critical threshold that needs to be reached to trigger an action potential in an axon?
During depolarization, which ion channels open to allow their respective ions to flow into the axon?
During depolarization, which ion channels open to allow their respective ions to flow into the axon?
Which of the following is NOT a key player in maintaining the resting membrane potential?
Which of the following is NOT a key player in maintaining the resting membrane potential?
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What happens during repolarization?
What happens during repolarization?
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What is the phenomenon of the membrane potential briefly becoming more negative than the resting potential after repolarization called?
What is the phenomenon of the membrane potential briefly becoming more negative than the resting potential after repolarization called?
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The sodium-potassium pump actively uses ATP to maintain its functionality and restore the resting membrane potential after the undershoot.
The sodium-potassium pump actively uses ATP to maintain its functionality and restore the resting membrane potential after the undershoot.
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What are the two key types of inputs that contribute to the combined input at the axon hillock?
What are the two key types of inputs that contribute to the combined input at the axon hillock?
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Which of the following is NOT a characteristic of voltage-gated channels?
Which of the following is NOT a characteristic of voltage-gated channels?
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Sodium channels open rapidly in response to depolarization, while potassium channels open more slowly, allowing potassium to exit the axon.
Sodium channels open rapidly in response to depolarization, while potassium channels open more slowly, allowing potassium to exit the axon.
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What is the relationship between linear input and nonlinear output in neurons?
What is the relationship between linear input and nonlinear output in neurons?
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Which of the following describes how artificial neural networks (ANNs) are inspired by biological neurons?
Which of the following describes how artificial neural networks (ANNs) are inspired by biological neurons?
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Neurons without axons communicate via graded potentials, which are localized signals that don't travel long distances.
Neurons without axons communicate via graded potentials, which are localized signals that don't travel long distances.
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Which of the following types of neurons has multiple appendages (neurites)?
Which of the following types of neurons has multiple appendages (neurites)?
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The axon is typically the only appendage that transmits electrical signals over long distances in vertebrates.
The axon is typically the only appendage that transmits electrical signals over long distances in vertebrates.
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What are the main functions of the dendrites and axon, respectively?
What are the main functions of the dendrites and axon, respectively?
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Action potentials are always generated at one specific point and travel down the axon without regenerating.
Action potentials are always generated at one specific point and travel down the axon without regenerating.
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Which of the following is NOT a characteristic of chemical synapses?
Which of the following is NOT a characteristic of chemical synapses?
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What is the role of neurotransmitters in chemical synaptic transmission?
What is the role of neurotransmitters in chemical synaptic transmission?
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Sherrington's work on reflexes suggested that:
Sherrington's work on reflexes suggested that:
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Electrical synapses are more common than chemical synapses.
Electrical synapses are more common than chemical synapses.
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The term 'reflex' refers to simple, automatic responses to stimuli that involve only the brain, not the spinal cord.
The term 'reflex' refers to simple, automatic responses to stimuli that involve only the brain, not the spinal cord.
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What did Sherrington's experiments with severed spinal cords demonstrate?
What did Sherrington's experiments with severed spinal cords demonstrate?
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Loewi's Experiment provided the first evidence that chemical substances (neurotransmitters) could induce electrical responses in other neurons.
Loewi's Experiment provided the first evidence that chemical substances (neurotransmitters) could induce electrical responses in other neurons.
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Which of the following is NOT true about the synaptic cleft?
Which of the following is NOT true about the synaptic cleft?
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What is the process of neurotransmitter release into the synaptic cleft called?
What is the process of neurotransmitter release into the synaptic cleft called?
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When neurotransmitters bind to receptors on the postsynaptic neuron, they can either:
When neurotransmitters bind to receptors on the postsynaptic neuron, they can either:
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What are the three main ways neurotransmitters are cleared from the synaptic cleft?
What are the three main ways neurotransmitters are cleared from the synaptic cleft?
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Ionotropic receptors are directly linked to ion channels and produce a fast, localized response when neurotransmitters bind.
Ionotropic receptors are directly linked to ion channels and produce a fast, localized response when neurotransmitters bind.
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Metabotropic receptors rely on indirect activation through G-proteins and produce slower but longer-lasting effects compared to ionotropic receptors.
Metabotropic receptors rely on indirect activation through G-proteins and produce slower but longer-lasting effects compared to ionotropic receptors.
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When a neurotransmitter binds to a G protein coupled receptor, what happens next?
When a neurotransmitter binds to a G protein coupled receptor, what happens next?
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What is the effect of cocaine on synaptic transmission?
What is the effect of cocaine on synaptic transmission?
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Which drug has a milder effect on dopamine reuptake compared to cocaine?
Which drug has a milder effect on dopamine reuptake compared to cocaine?
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Auto-receptors are located on the presynaptic neuron and detect neurotransmitter levels to regulate further release if necessary.
Auto-receptors are located on the presynaptic neuron and detect neurotransmitter levels to regulate further release if necessary.
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Marijuana activates auto-receptors, leading to increased neurotransmitter release and heightened anxiety.
Marijuana activates auto-receptors, leading to increased neurotransmitter release and heightened anxiety.
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Which of the following describes the effect of agonist drugs?
Which of the following describes the effect of agonist drugs?
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Receptors can be either ionotropic or metabotropic, with different downstream effects.
Receptors can be either ionotropic or metabotropic, with different downstream effects.
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What are the two main concepts to review regarding neurotransmission?
What are the two main concepts to review regarding neurotransmission?
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Study Notes
Action Potential Diagram
- The diagram shows different phases of the action potential (A, B, C, D).
- Phase A: Resting Membrane Potential (-70mV). Key players are the sodium-potassium pump, actively transporting sodium ions (Na+) out and potassium ions (K+) in, creating a concentration gradient.
- Phase B: Depolarization (-55mV). Voltage-gated sodium channels open, sodium ions rush inwards. This causes the inside of the axon to become more positive.
- Phase C: Peak of Action Potential (+40mV). Sodium channels close and inactivate. Potassium channels fully open, potassium ions exit the axon.
- Phase D: Repolarization and Undershoot Potassium ions exit the axon, making the inside of the axon less positive. The inside of the membrane becomes more negative than the resting potential (undershoot/hyperpolarization). Sodium-potassium pumps restore the resting membrane potential (-70mV).
Action Potential Initiation
- Action potentials begin when the combined inputs from other neurons (or sensory receptors) cause the membrane potential at the Axon Hillock to reach a threshold (-55mV).
- Summation of EPSPs (excitatory postsynaptic potentials) and IPSPs (inhibitory postsynaptic potentials) determine this.
Voltage-Gated Channels and Action Potential Propagation
- Voltage-gated sodium and potassium channels open and close in response to membrane potential changes. Sodium channels open rapidly in response to depolarization, allowing sodium to rush in. They quickly inactivate when the peak of the action potential is reached. Potassium channels open more slowly, allowing potassium to exit, repolarizing the membrane.
Communication in Local Neurons
- Local neurons communicate via graded potentials.
- Signals don't need to travel long distances.
- Communication is localized across the soma.
Neuron Classification & Structure
- Neurons are basic units of the nervous system. Classified by the number of neurites (appendages)
- Unipolar: one appendage
- Bipolar: two appendages (one dendrite, one axon)
- Multipolar: multiple appendages (common in vertebrates, especially in the brain & spinal cord)
Synaptic Transmission
- Synapses are junctions between two neurons.
- Neurotransmitters are chemicals that transmit signals across synapses.
- Chemical synapses are the most common type, releasing neurotransmitters into the synaptic cleft.
- Electrical synapses use gap junctions to allow direct electrical communication.
Types of Receptors
- Ionotropic receptors: Directly linked to ion channels. Neurotransmitter binding opens or closes ion channels. Fast response.
- Metabotropic receptors: Indirectly influence the neuron via G-proteins. Slower, more prolonged response.
Effects of Drugs on Synaptic Transmission
- Drugs like cocaine block dopamine reuptake, leading to prolonged dopamine presence and potential withdrawal symptoms.
- Ritalin has a similar mechanism but with milder effects.
- Nicotine binds to receptors affecting synaptic transmission.
Overview of Neurotransmission
- Intra-neuron communication is electrical.
- Inter-neuron communication is chemical, using neurotransmitters.
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Description
This quiz explores the phases of action potential, including resting membrane potential, depolarization, peak action potential, and repolarization. Understand the role of sodium-potassium pumps and voltage-gated channels in initiating and propagating action potentials in neurons.
