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What is the primary function of a synapse?
What is the primary function of a synapse?
Which structure connects the presynaptic and postsynaptic cells in an electrical synapse?
Which structure connects the presynaptic and postsynaptic cells in an electrical synapse?
What is the distance between two cells connected by gap junctions?
What is the distance between two cells connected by gap junctions?
Which type of synapse is characterized by the presence of a synaptic cleft?
Which type of synapse is characterized by the presence of a synaptic cleft?
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What role does calcium ions play in chemical synapses?
What role does calcium ions play in chemical synapses?
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Which type of synapse typically allows for quicker transmission of signals?
Which type of synapse typically allows for quicker transmission of signals?
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What is formed between cells during electrical synapse stimulation?
What is formed between cells during electrical synapse stimulation?
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Which of the following describes the postsynaptic structure in chemical transmission?
Which of the following describes the postsynaptic structure in chemical transmission?
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What effect does botulinum toxin have on muscle contraction?
What effect does botulinum toxin have on muscle contraction?
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Which toxin selectively destroys synaptobrevin in inhibitory interneurons?
Which toxin selectively destroys synaptobrevin in inhibitory interneurons?
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In Lambert-Eaton Syndrome, what do autoantibodies primarily target?
In Lambert-Eaton Syndrome, what do autoantibodies primarily target?
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What is the primary way botulinum toxin can be contracted through food?
What is the primary way botulinum toxin can be contracted through food?
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Which condition leads to the accumulation of acetylcholine in the synaptic cleft?
Which condition leads to the accumulation of acetylcholine in the synaptic cleft?
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What type of paralysis can result from tetanus toxin affecting inhibitory interneurons?
What type of paralysis can result from tetanus toxin affecting inhibitory interneurons?
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What is a common characteristic of botulinum toxin production locations?
What is a common characteristic of botulinum toxin production locations?
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What are the cosmetic applications of botulinum toxin commonly referred to?
What are the cosmetic applications of botulinum toxin commonly referred to?
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Which statement about acetylcholine is correct?
Which statement about acetylcholine is correct?
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What is the primary mediator in a chemical synapse?
What is the primary mediator in a chemical synapse?
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Which of the following statements about V-SNARE and T-SNARE proteins is accurate?
Which of the following statements about V-SNARE and T-SNARE proteins is accurate?
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Which characteristic is NOT associated with electrical synapses?
Which characteristic is NOT associated with electrical synapses?
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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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What condition is characterized by paralysis due to the blockage of neurotransmitter release?
What condition is characterized by paralysis due to the blockage of neurotransmitter release?
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Which of the following is a key function of acetylcholine in the peripheral nervous system?
Which of the following is a key function of acetylcholine in the peripheral nervous system?
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What differentiates chemical synapses from electrical synapses?
What differentiates chemical synapses from electrical synapses?
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What triggers the opening of voltage-gated Ca+2 channels in the presynaptic neuron?
What triggers the opening of voltage-gated Ca+2 channels in the presynaptic neuron?
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What is the role of V-SNAREs and T-SNAREs in neurotransmitter release?
What is the role of V-SNAREs and T-SNAREs in neurotransmitter release?
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What is the main effect of acetylcholine (ACh) binding to the nicotinic ACh receptor?
What is the main effect of acetylcholine (ACh) binding to the nicotinic ACh receptor?
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What determines the number of vesicles released into the synaptic cleft?
What determines the number of vesicles released into the synaptic cleft?
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Which ion primarily enters the postsynaptic cell when ACh binds to its receptor?
Which ion primarily enters the postsynaptic cell when ACh binds to its receptor?
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What type of potential is formed in the region where ACh binds to the postsynaptic receptor?
What type of potential is formed in the region where ACh binds to the postsynaptic receptor?
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How does an excitatory postsynaptic potential (EPP) contribute to action potential generation?
How does an excitatory postsynaptic potential (EPP) contribute to action potential generation?
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What is the primary effect of curare on the neuromuscular junction?
What is the primary effect of curare on the neuromuscular junction?
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Which neurotransmitter is primarily associated with excitatory functions within the CNS?
Which neurotransmitter is primarily associated with excitatory functions within the CNS?
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What distinguishes EPSP from IPSP in terms of its effect on the postsynaptic neuron?
What distinguishes EPSP from IPSP in terms of its effect on the postsynaptic neuron?
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Which neurotransmitter is primarily associated with producing EPSP?
Which neurotransmitter is primarily associated with producing EPSP?
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What happens to acetylcholine in the synaptic cleft when curare is applied?
What happens to acetylcholine in the synaptic cleft when curare is applied?
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Which of the following processes involves signals from multiple presynaptic neurons converging on a single postsynaptic neuron?
Which of the following processes involves signals from multiple presynaptic neurons converging on a single postsynaptic neuron?
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Which ion channels opening would generally lead to hyperpolarization in the postsynaptic neuron?
Which ion channels opening would generally lead to hyperpolarization in the postsynaptic neuron?
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How does the sum of EPSP and IPSP influence the firing of a postsynaptic neuron?
How does the sum of EPSP and IPSP influence the firing of a postsynaptic neuron?
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What effect does an increase in IPSP have on the likelihood of a postsynaptic neuron firing?
What effect does an increase in IPSP have on the likelihood of a postsynaptic neuron firing?
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Study Notes
Nervous System Physiology Essentials 3
- The connection between two cells is called a synapse.
- In the central nervous system (CNS), both cells are neurons.
- In the peripheral nervous system, the second cell can be a neuron, a muscle cell, or a gland cell.
- The synapse between a neuron and a muscle cell is called a neuromuscular junction.
- The cell before the synapse is the presynaptic cell.
- The cell behind the synapse is the postsynaptic cell.
Synapse Types
- Synapses are connections that transmit information between neurons.
- They are categorized into different types based on function and structural features.
- The main types of synapses are electrical and chemical synapses.
- Synapses can also be categorized by their structural features: axodendritic, axosomatic, and axoaxonic synapses.
- Or by their functional features: excitatory and inhibitory synapses.
Electrical Synapse
- Electrical synapses establish a direct connection between neurons, allowing ions to flow.
- These provide a rapid transmission of information.
- Ions are supplied by proteins called gap junctions.
- Gap junctions create a small space between cells (24 nm), much shorter than a chemical synapse.
- A syncytium is formed between the cells, allowing for simultaneous stimulation.
- Nerve conduction is based on ion balance.
- Chemical substances are not needed to initiate conduction.
- These connections are common in smooth muscle and heart muscle.
Chemical Synapse
- Chemical synapses are more common than electrical synapses.
- A physical space, the synaptic cleft, separates the nerve endings.
- The synaptic cleft is 20-40 nm wide.
- Chemical transmission begins at the axon end of the presynaptic neuron.
- When an action potential arrives, neurotransmitters are released into the synaptic cleft by calcium entering the cell.
- These neurotransmitters bind to receptors on the postsynaptic neuron, triggering a response.
- The entire postsynaptic structure is called the motor endplate.
Neurotransmitters
- Neurotransmitters are chemical signals used by nerve cells to transmit information between each other.
- They are stored in synaptic vesicles and released when an action potential reaches the presynaptic neuron.
- They bind to receptors on the postsynaptic cell, triggering a response.
- Examples include glutamate (excitatory), GABA (inhibitory), and acetylcholine.
Conditions Affecting the Neuromuscular Junction
- Diseases and conditions can affect the neuromuscular junction, such as Lambert-Eaton syndrome, Botulism, Tetanus, Myasthenia Gravis, and Curare Effect.
- In these conditions there are problems in acetylcholine release or reception, or the structure of the connection.
Botulinum Toxin
- Botulinum toxin is a potent neurotoxin produced by Clostridium botulinum.
- It blocks the release of acetylcholine, which inhibits muscle contraction.
- It's used medically to reduce muscle spasms, migraines, and other conditions.
Common Ways to Be Infected with Botulinum Toxin
- Botulism can infect people through contaminated food (often homemade canned food), and less commonly through honey.
Tetanus
- Tetanus toxin destroys synaptobrevin.
- It's produced by Clostridium tetani.
- This causes a blockade of inhibitory interneurons.
- Resulting in muscle contraction and spastic paralysis.
Lambert-Eaton Syndrome
- This is a rare autoimmune disease.
- Autoantibodies destroy a specific subtype of calcium channels.
- This reduces calcium-dependent acetylcholine release.
- Leads to muscle weakness.
Myasthenia Gravis
- Autoantibodies form against acetylcholine receptors (AChR).
- This leads to the accumulation of acetylcholine in the synaptic cleft.
- Results in delayed neurotransmission.
Curare Effect
- Curare is a natural compound from tropical plants used as a muscle relaxant.
- It competes with acetylcholine, blocking receptors.
- This causes muscle paralysis.
- It often affects respiratory muscles leading to asphyxy.
EPSP and IPSP
- EPSPs (excitatory postsynaptic potentials) increase the likelihood of producing an action potential in the receiving neuron.
- IPSPs (inhibitory postsynaptic potentials) make the receiving neuron less likely to fire.
- Summation of EPSP and IPSP influences the firing of the receiving neuron.
Summation
- Temporal summation occurs when successive stimuli arrive rapidly at the synapse.
- Spatial summation occurs when stimuli from multiple synapses act on the same post-synaptic neuron to generate a response.
Convergence and Divergence
- Convergence is when multiple presynaptic neurons connect to a single postsynaptic neuron.
- Divergence is when one presynaptic neuron connects to multiple postsynaptic neurons.
V-SNARE and T-SNARE Proteins
- These are essential in the release of neurotransmitters.
- V-SNARE proteins are found on the vesicle membranes.
- T-SNARE proteins are found on the target cell membranes.
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Description
This quiz covers essential concepts in nervous system physiology, focusing on synapses and their types. Explore the differences between electrical and chemical synapses, as well as structural and functional classifications. Test your understanding of the connections that facilitate communication between neurons.
