16 Questions
Which structure is located between a nerve fiber and a muscle fiber?
Motor end plate (MEP)
What is the main component of the motor pool?
Anterior horn cells (AHCs)
What is the main function of the neuromuscular junction (NMJ)?
To transmit electrical signals from the motor neuron to the muscle fiber
Which proteins form the contractile proteins in skeletal muscles?
Actin and myosin
What does the motor unit consist of?
Motor neuron + its axon + muscle fibers
What is responsible for transmitting electrical signals from the motor neuron to the muscle fiber?
Neuromuscular transmission (The end plate potential, EPP)
What is the function of Troponin T in muscle contraction?
Binds to tropomyosin
During muscle contraction, what leads to the movement of tropomyosin laterally, uncovering the binding sites of actin for the myosin heads?
Binding of troponin C with calcium
Which structure is responsible for the rapid spread of the action potential in muscle fibers?
T-tubules
What is the energy source required for the mechanism of muscle contraction?
Breakdown of ATP by ATPase activity of myosin heads in the presence of Ca++ ions
What is the function of troponin I during muscle contraction?
Inhibits binding of actin to myosin
What is the role of myosin heads during muscle contraction?
Breakdown of ATP to ADP by ATPase activity
Which protein keeps actin structure and covers actin binding sites during muscle contraction?
Tropomyosin
What is the function of troponin C during muscle contraction?
Binds with calcium
What is the function of sarcotubular system in muscle contraction?
Rapid spread of action potential
What leads to muscle relaxation during excitation-contraction coupling?
Breakdown of ATP by active Ca++ pump
Study Notes
Neuromuscular Junction (NMJ)
- The neuromuscular junction (NMJ) is located between a nerve fiber and a muscle fiber.
- The main function of the NMJ is to transmit electrical signals from the motor neuron to the muscle fiber.
Motor Unit
- The motor unit consists of a motor neuron and all the muscle fibers it innervates.
Muscle Contraction
- Actin and myosin form the contractile proteins in skeletal muscles.
- The motor unit is responsible for transmitting electrical signals from the motor neuron to the muscle fiber.
- During muscle contraction, the binding of calcium to troponin C leads to the movement of tropomyosin laterally, uncovering the binding sites of actin for the myosin heads.
- The myosin heads pull the actin filament towards the center of the sarcomere, causing muscle contraction.
- Tropomyosin keeps the actin structure and covers actin binding sites during muscle contraction, preventing muscle contraction.
Muscle Relaxation
- The troponin I and troponin T complex helps to relax the muscle by blocking the binding of myosin heads to actin.
Muscle Fiber
- The T-tubular system is responsible for the rapid spread of the action potential in muscle fibers.
- The energy source required for the mechanism of muscle contraction is ATP.
Proteins and their Functions
- Troponin T helps to relax the muscle by blocking the binding of myosin heads to actin.
- Troponin I helps to regulate muscle contraction and relaxation.
- Troponin C binds to calcium, leading to muscle contraction.
- Sarcotubular system helps to regulate muscle contraction and relaxation by controlling the release and uptake of calcium ions.
Test your knowledge on the neuromuscular junction (NMJ) and muscle contraction with this quiz. Questions cover the definition and structure of NMJ, functional structure of skeletal muscles, and excitation-contraction coupling.
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