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Questions and Answers
What triggers the voltage-gated Ca+2 channels to open in the presynaptic neuron?
What triggers the voltage-gated Ca+2 channels to open in the presynaptic neuron?
What is released into the synaptic cleft following the fusion of the vesicle with the presynaptic membrane?
What is released into the synaptic cleft following the fusion of the vesicle with the presynaptic membrane?
Which type of channel does the postsynaptic nicotinic Ach receptor (nAcHR) represent?
Which type of channel does the postsynaptic nicotinic Ach receptor (nAcHR) represent?
What primarily determines the number of vesicles discharged into the synaptic cleft?
What primarily determines the number of vesicles discharged into the synaptic cleft?
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What occurs after Ach binds to postsynaptic nicotinic receptors?
What occurs after Ach binds to postsynaptic nicotinic receptors?
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What type of potential is generated following the accumulation of excitatory postsynaptic potentials (EPP)?
What type of potential is generated following the accumulation of excitatory postsynaptic potentials (EPP)?
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Which neurotransmitter is known as the most common excitatory neurotransmitter in the CNS?
Which neurotransmitter is known as the most common excitatory neurotransmitter in the CNS?
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What is the primary role of GABA in the central nervous system?
What is the primary role of GABA in the central nervous system?
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What type of synapse is formed between a neuron and a muscle cell?
What type of synapse is formed between a neuron and a muscle cell?
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What is a distinguishing feature of electrical synapses compared to chemical synapses?
What is a distinguishing feature of electrical synapses compared to chemical synapses?
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What provides the gap for ion flow in electrical synapses?
What provides the gap for ion flow in electrical synapses?
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Which of the following accurately describes the synaptic cleft in chemical synapses?
Which of the following accurately describes the synaptic cleft in chemical synapses?
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What initiates the release of neurotransmitters in chemical synapses?
What initiates the release of neurotransmitters in chemical synapses?
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Which type of synapse is characterized by almost no physical distance between connected cells?
Which type of synapse is characterized by almost no physical distance between connected cells?
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What is formed when cells communicate through electrical synapses?
What is formed when cells communicate through electrical synapses?
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In which part of the nervous system are gap junctions predominantly found?
In which part of the nervous system are gap junctions predominantly found?
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What role does acetylcholine play in the central nervous system (CNS)?
What role does acetylcholine play in the central nervous system (CNS)?
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Which characteristic distinguishes chemical synapses from electrical synapses?
Which characteristic distinguishes chemical synapses from electrical synapses?
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What is the primary function of V-SNARE proteins?
What is the primary function of V-SNARE proteins?
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Which of the following conditions affects the neuromuscular junction?
Which of the following conditions affects the neuromuscular junction?
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What is the role of synaptotagmin in the SNARE complex?
What is the role of synaptotagmin in the SNARE complex?
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How does botulinum toxin affect muscle movement?
How does botulinum toxin affect muscle movement?
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What primarily mediates the transmission in electrical synapses?
What primarily mediates the transmission in electrical synapses?
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Which proteins form the SNARE complex during exocytosis?
Which proteins form the SNARE complex during exocytosis?
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What is the mechanism of action of botulinum toxin on neurotransmitter release?
What is the mechanism of action of botulinum toxin on neurotransmitter release?
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Which of the following is a clinical use of botulinum toxin?
Which of the following is a clinical use of botulinum toxin?
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Which food source poses a risk for botulism due to the presence of botulinum spores?
Which food source poses a risk for botulism due to the presence of botulinum spores?
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How does tetanus toxin affect neurotransmitter release in the body?
How does tetanus toxin affect neurotransmitter release in the body?
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What autoimmune response does Lambert-Eaton Syndrome trigger?
What autoimmune response does Lambert-Eaton Syndrome trigger?
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Which mechanism contributes to the muscle weakness observed in Myasthenia Gravis?
Which mechanism contributes to the muscle weakness observed in Myasthenia Gravis?
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What is the primary source of botulinum toxin?
What is the primary source of botulinum toxin?
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What is the effect of the compound curare in the body?
What is the effect of the compound curare in the body?
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What is the primary action of curare on the neuromuscular junction?
What is the primary action of curare on the neuromuscular junction?
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What happens to acetylcholine levels when curare is applied?
What happens to acetylcholine levels when curare is applied?
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Which neurotransmitter is primarily involved in producing an EPSP?
Which neurotransmitter is primarily involved in producing an EPSP?
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What is the effect of inhibitory neurotransmitters on the postsynaptic neuron?
What is the effect of inhibitory neurotransmitters on the postsynaptic neuron?
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What is convergence in the context of neuron signaling?
What is convergence in the context of neuron signaling?
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What primarily determines whether a postsynaptic neuron will fire an action potential?
What primarily determines whether a postsynaptic neuron will fire an action potential?
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What effect does hyperpolarization have on a neuron?
What effect does hyperpolarization have on a neuron?
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How does the opening of Na channels impact a postsynaptic potential?
How does the opening of Na channels impact a postsynaptic potential?
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Study Notes
Nervous System Physiology Essentials 3
- The nervous system is composed of neurons and other cells
- The connection between a neuron and another cell is a synapse
- In the central nervous system (CNS), both connected cells are neurons
- In the peripheral nervous system, the second cell can be a neuron, a muscle, or a gland cell.
- The synapse between a neuron and a muscle cell is called a neuromuscular junction
- The cell before the synapse is presynaptic
- The cell after the synapse is postsynaptic
Synapse Types
- Synapses are connections that allow the transmission of information between neurons.
- They are categorized according to structure and function
- Synapses can be electrical or chemical
- Electrical synapses allow ions to flow directly between cells through gap junctions
- Chemical synapses involve the release of neurotransmitters into a synaptic cleft
- Electrical synapses have a much faster transmission speed than chemical synapses
Electrical Synapse
- Electrical synapses utilize gap junctions to transmit signals.
- These junctions create a very short distance between the cells
- Gap junctions connect the presynaptic and postsynaptic cells
- The distance between the cells is 2-4nm
- The transmission occurs very quickly, approximately 6 times faster than in a chemical synapse
- They are ion-based
- In electrical communication, nerve conduction is based on an ion balance
- They are present in smooth muscle and heart muscle
Chemical Synapse
- Chemical synapses are more common than electrical synapses.
- A physical space called a synaptic cleft exists between neuron endings.
- The synaptic cleft is 20-40 nanometers wide
- Signals are transmitted via neurotransmitters
- Neurotransmitters are released from presynaptic terminals into the synaptic cleft
Neurotransmitters
- Neurotransmitters are signaling molecules
- They transmit signals between nerve cells and other cells.
- They're stored in synaptic vesicles
- The action potential results in the release of neurotransmitters at the presynaptic membrane
- Important Neurotransmitters: Glutamate, GABA, acetylcholine, and others
T-SNARE and V-SNARE proteins
- V-SNARE and T-SNARE proteins are critical for the fusion of synaptic vesicles with the presynaptic membrane
- These proteins allow the fusion of vesicles and release of neurotransmitters
Conditions Affecting the Neuromuscular Junction
- Lambert-Eaton Syndrome: Autoimmune disease affecting calcium channels, hindering neurotransmitter release.
- Botulism: A neurotoxin that blocks the release of acetylcholine, causing muscle weakness or paralysis
- Tetanus: A neurotoxin that interferes with inhibitory neurotransmitters, causing muscle spasms
- Myasthenia Gravis: Autoimmune disease affecting acetylcholine receptors, hindering neuromuscular transmission
- Curare effect: Substance that blocks acetylcholine receptors, leading to muscle paralysis.
EPSPs and IPSPs
- EPSPs (excitatory postsynaptic potentials) are a brief depolarization of a postsynaptic membrane caused by excitatory neurotransmitters from the presynaptic neuron
- IPSPs (inhibitory postsynaptic potentials) are a brief hyperpolarization of the membrane
- These changes are small electrical signals called postsynaptic potentials
- Summation of various EPSPs and IPSPs determines whether the postsynaptic neuron will reach the action potential threshold
Convergence and Divergence
- Convergence: A single postsynaptic neuron receives input from multiple presynaptic neurons.
- Divergence: A single presynaptic neuron sends signals to multiple postsynaptic neurons.
- Facilitated: Temporary increase in the excitability of a neuron following repeated stimulation with additional inputs or signals.
Summation
- Summation is the process by which multiple graded potentials combine to affect a postsynaptic neuron.
- Temporal summation involves repeated stimulation from a single presynaptic neuron in a short period
- Spatial summation involves simultaneous stimulation of a postsynaptic neuron from multiple presynaptic neurons.
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Description
Explore the fundamentals of nervous system physiology including neuron structure, synapse types, and their functionalities. Understand the differences between electrical and chemical synapses and their roles in neurotransmission. This quiz will test your knowledge on the essential concepts of how neurons communicate within the nervous system.
