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Which type of muscle is responsible for voluntary actions?
Which type of muscle is responsible for voluntary actions?
What is the shape of cardiac muscle?
What is the shape of cardiac muscle?
What is the functional contractile unit of a muscle?
What is the functional contractile unit of a muscle?
Which type of muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries?
Which type of muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries?
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What is the role of the Neuromuscular Junction (NMJ)?
What is the role of the Neuromuscular Junction (NMJ)?
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Which structure in the NMJ contains the enzyme responsible for hydrolysis of free acetylcholine?
Which structure in the NMJ contains the enzyme responsible for hydrolysis of free acetylcholine?
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What is the role of synaptic plasticity in neuromuscular transmission?
What is the role of synaptic plasticity in neuromuscular transmission?
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Which component is part of the Neuromuscular Junction (NMJ)?
Which component is part of the Neuromuscular Junction (NMJ)?
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What percentage of total body mass is composed of muscles?
What percentage of total body mass is composed of muscles?
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Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?
Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?
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What is the shape of skeletal muscle cells?
What is the shape of skeletal muscle cells?
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Which muscle type is involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract?
Which muscle type is involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract?
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Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?
Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?
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What is the functional contractile unit of a muscle?
What is the functional contractile unit of a muscle?
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Which muscle type appears red due to high contents of myoglobin, mitochondria, and capillaries?
Which muscle type appears red due to high contents of myoglobin, mitochondria, and capillaries?
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What is the shape of cardiac muscle cells?
What is the shape of cardiac muscle cells?
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Which type of muscle is responsible for voluntary actions?
Which type of muscle is responsible for voluntary actions?
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Which type of muscle fibers have a high resistance to fatigue?
Which type of muscle fibers have a high resistance to fatigue?
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What are the three structures that comprise the Neuromuscular Junction (NMJ)?
What are the three structures that comprise the Neuromuscular Junction (NMJ)?
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What is the role of acetylcholine in neuromuscular transmission?
What is the role of acetylcholine in neuromuscular transmission?
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Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
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What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
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What happens to the released acetylcholine during diffusion across the synaptic cleft?
What happens to the released acetylcholine during diffusion across the synaptic cleft?
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What are the products of the hydrolysis of acetylcholine by acetylcholinesterase?
What are the products of the hydrolysis of acetylcholine by acetylcholinesterase?
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What is the role of synaptic cleft in neuromuscular transmission?
What is the role of synaptic cleft in neuromuscular transmission?
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What is the role of the postsynaptic muscle membrane in the Neuromuscular Junction (NMJ)?
What is the role of the postsynaptic muscle membrane in the Neuromuscular Junction (NMJ)?
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What is the role of synaptic plasticity in neuromuscular transmission?
What is the role of synaptic plasticity in neuromuscular transmission?
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Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?
Which type of muscle is responsible for functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems?
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What is the role of acetylcholine in neuromuscular transmission?
What is the role of acetylcholine in neuromuscular transmission?
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What is the shape of cardiac muscle cells?
What is the shape of cardiac muscle cells?
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What is the functional contractile unit of a muscle?
What is the functional contractile unit of a muscle?
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What percentage of total body mass is composed of muscles?
What percentage of total body mass is composed of muscles?
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Which structures are involved in the Neuromuscular Junction (NMJ)?
Which structures are involved in the Neuromuscular Junction (NMJ)?
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What is the role of acetylcholine in neuromuscular transmission?
What is the role of acetylcholine in neuromuscular transmission?
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What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
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Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
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What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?
What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?
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Which type of muscle is responsible for voluntary actions?
Which type of muscle is responsible for voluntary actions?
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What is the shape of cardiac muscle cells?
What is the shape of cardiac muscle cells?
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What is the role of smooth muscle in the body?
What is the role of smooth muscle in the body?
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What is the functional contractile unit of a muscle?
What is the functional contractile unit of a muscle?
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Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?
Where do the large myelinated α motor neurons that innervate vertebrate skeletal muscles originate from?
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Which type of muscle fibers have a high resistance to fatigue?
Which type of muscle fibers have a high resistance to fatigue?
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What is the role of acetylcholine in neuromuscular transmission?
What is the role of acetylcholine in neuromuscular transmission?
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What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
What is the function of calcium ion signaling in acetylcholine vesicles exocytosis?
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Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
Where are synaptic vesicles (SVs) synthesized in the neuronal cell?
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What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?
What percentage of the released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft?
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Skeletal muscles are responsible for voluntary actions.
Skeletal muscles are responsible for voluntary actions.
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Smooth muscles are involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract.
Smooth muscles are involved in hypertension, atherosclerosis, asthma, and disorders of the gastrointestinal tract.
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The motor unit is composed of a single myelinated α motor neuron and all muscle fibers that receive innervation from this single neuron.
The motor unit is composed of a single myelinated α motor neuron and all muscle fibers that receive innervation from this single neuron.
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True or false: Small motor units innervate the 'red slow' muscle fibers.
True or false: Small motor units innervate the 'red slow' muscle fibers.
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True or false: Large motor units innervate the 'white or pale fast' muscle fibers.
True or false: Large motor units innervate the 'white or pale fast' muscle fibers.
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True or false: The slow muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries.
True or false: The slow muscle fibers appear red due to high contents of myoglobin, mitochondria, and capillaries.
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True or false: The synaptic cleft contains the enzyme responsible for hydrolysis of free acetylcholine.
True or false: The synaptic cleft contains the enzyme responsible for hydrolysis of free acetylcholine.
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Study Notes
Neuromuscular Physiology
- Muscles account for 45-50% of total body mass, with skeletal muscles making up approximately 40% of body mass.
- Muscle cells are specialized for converting chemical energy into mechanical energy.
Muscle Types
- Muscles are classified into three main types: skeletal, smooth, and cardiac.
- Skeletal muscles are multinucleated, tubular, and responsible for voluntary actions.
- Cardiac muscles are branched, may be mono- or binucleated, and contain intercalated discs.
- Cardiac muscles are involved in functions related to the cardiovascular, respiratory, gastrointestinal, and genitourinary systems.
Motor Units
- Vertebrate skeletal muscles are innervated by large myelinated α motor neurons originating from the brainstem or spinal cord.
- A motor unit consists of a single α motor neuron and all muscle fibers innervated by it.
- Large motor nerves innervate more muscle fibers than smaller motor nerves.
- Small motor units innervate "red slow" muscle fibers, while large motor units innervate "white or pale fast" muscle fibers.
The Neuromuscular Junction (NMJ)
- The NMJ consists of three structures: motor neuron, muscle fiber, and glial cells (Schwann cells).
- The NMJ is responsible for transmitting electrical impulses from the nerve terminal to the skeletal muscle via acetylcholine.
- The synaptic cleft contains basal lamina with acetylcholinesterase enzyme, which hydrolyzes free acetylcholine.
- The postsynaptic muscle membrane has highly infolded folds (secondary folds) with nAChRs concentrated at the crests and voltage-gated sodium channels in the troughs.
Synaptic Plasticity
- Synaptic plasticity is the ability of individual synaptic junctions to respond to use or disuse.
- The plasticity of neuromuscular transmission depends on the synthesis, storage, and release of acetylcholine, binding to nicotinic receptors, and rapid hydrolysis by acetylcholinesterase.
Presynaptic Region
- Synaptic vesicles (SVs) are specialized secretory organelles that store acetylcholine.
- SVs possess proteins involved in neurotransmitter uptake and membrane traffic.
- Calcium ion signaling plays a crucial role in acetylcholine vesicles exocytosis.
Acetylcholine (ACh)
- ACh is an important neurotransmitter involved in brain functions (memory) and body functions (muscle contractions).
- ACh is synthesized in the nerve terminal from acetyl coenzyme A and choline.
- Each vesicle contains 5,000 to 10,000 molecules of acetylcholine, referred to as a "quantum" of transmitter.
- Released acetylcholine is rapidly hydrolyzed by acetylcholinesterase during diffusion across the synaptic cleft.
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Description
Test your knowledge of neuromuscular physiology and the neuromuscular junction (NMJ) with this quiz. Learn about the components of the NMJ and how muscles make up a significant portion of our body mass.
