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What is the sequence of structures that action potentials must move through to excite skeletal muscle contraction?
Excitation begins as a motor neuron transmits an action potential to the neuromuscular junction where it gets propagated along the muscle cell. This action potential is an electrical impulse that depolarizes the muscle cell membrane, the sarcolemma, which then releases ions in the sacroplasmic reticulum and transverse tubules. When this happens calcium is released into the sarcomeres that contain actin and myosin myofilaments. The calcium unlocks the binding sites and creates crossbridges with the globular heads on the mysoin fibers. With ATP as the energy source, this crossbridging brings the Z-lines closed together and the muscle fiber contracts.
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Does skeletal muscle have T-tubules and what is their function in muscle contraction?
Yes, skeletal muscle has T-tubules, which are invaginations of the cell membrane that allow for the rapid transmission of action potentials deep into the muscle fiber. This helps to coordinate the contraction of muscle fibers by ensuring that all parts of the muscle fiber receive the signal to contract simultaneously.
What type of muscle is capable of rapid contraction and causes skeletal movement?
Skeletal or voluntary muscle is capable of rapid contraction and is responsible for skeletal movement.
How can gradation of skeletal muscle contraction be accomplished?
controlled output of action potentials, progressive recruitment of motor units, control of the rate of attachment/reattachment of actin and myosin heads and the power stroke rate
Does stretch have any effect on skeletal muscle contraction?
yes skeletal muscle stretch by means of contraction.
What are the structures within the muscle fiber that shorten to cause skeletal muscle fiber contraction?
The structures within the muscle fiber that shorten to cause skeletal muscle contraction are called myofibrils. Myofibrils are composed of repeating units called sarcomeres, which contain thick and thin filaments made of proteins (actin and myosin). When the muscle fiber is stimulated by a nerve impulse, the myosin heads interact with the actin filaments to generate the force required for muscle contraction.
Action potentials are conducted into a skeletal muscle fiber by?
C. neuromuscular junctions
What affect does lowering extracellular calcium have on the resting membrane potential of a neuron?
Low calcium levels in the extracellular fluid increase the permeability of neuronal membranes to sodium ions, causing a progressive depolarization, which increases the possibility of action potentials. These action potentials may be spontaneously generated, causing contraction of skeletal muscles (tetany).
How does the contraction of the I band contribute to the overall function of skeletal muscle?
The contraction of the I band in skeletal muscle helps to shorten the muscle fibers, allowing for movement and muscle contraction. This contributes to the overall function of skeletal muscle by enabling the muscle to generate force and produce movement.
The first step toward generating a skeletal muscle contraction is The first step toward generating a skeletal muscle contraction is?
stimulation of the muscle by a nerve ending.
What band shortens during skeletal muscle contraction?
during skeletal muscle contraction ,I band and H zone shortens. Sarcomeres
The action potential is conducted into a skeletal muscle fiber by?
The action potential is conducted into a skeletal muscle fiber by the depolarization of the motor end plate, which triggers the opening of voltage-gated sodium channels. This causes an influx of sodium ions into the muscle fiber, leading to depolarization and the initiation of muscle contraction.
Do skeletal muscles have involuntary muscle?
The skeletal muscles do have the involuntary muscle because they help it in the contraction process.
