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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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What type of fiber Terminal cisternae?
Terminal cisternae are specialized structures found in skeletal muscle fibers that are part of the sarcoplasmic reticulum. They serve as reservoirs for calcium ions, which are essential for muscle contraction. These cisternae are located adjacent to the T-tubules and play a crucial role in the excitation-contraction coupling process by releasing calcium in response to action potentials. Their arrangement helps ensure rapid and coordinated muscle contraction.
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.
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
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.
Which motor neuron is in charge of muscle contraction?
The motor neuron responsible for muscle contraction is the alpha motor neuron. These neurons reside in the spinal cord and project to skeletal muscles, where they release the neurotransmitter acetylcholine at the neuromuscular junction. This release initiates muscle contraction by triggering action potentials in muscle fibers, leading to their shortening and generating movement.
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.
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).
Action potentials are conducted into a skeletal muscle fiber by?
C. neuromuscular junctions
What are the rod-like structures within the skeletal muscle fiber that contain thin and thick filaments organized into sarcomeres?
The rod-like structures within skeletal muscle fibers are known as myofibrils. These myofibrils are composed of repeating units called sarcomeres, which contain organized arrangements of thin filaments (primarily actin) and thick filaments (primarily myosin). The coordinated contraction of these sarcomeres results in muscle contraction. Myofibrils are essential for the overall function and strength of skeletal muscle tissue.
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.
What band shortens during skeletal muscle contraction?
during skeletal muscle contraction ,I band and H zone shortens. Sarcomeres
