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What part of the skeletal muscle cell releases calcium when stimulated by the tubules?
The part of the skeletal muscle cell that releases calcium when stimulated by the tubules is the sarcoplasmic reticulum (SR). Specifically, the terminal cisternae of the SR release calcium ions into the cytoplasm in response to the action potential transmitted along the T-tubules. This release of calcium is essential for muscle contraction, as it triggers the interaction between actin and myosin filaments.
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What is the significance of the skeletal muscle fiber triad relationship?
The skeletal muscle fiber triad relationship refers to the structural arrangement of a T-tubule sandwiched between two terminal cisternae of the sarcoplasmic reticulum. This triad structure plays a crucial role in excitation-contraction coupling, as it allows for the transmission of action potentials deep into the muscle fiber to trigger calcium release from the sarcoplasmic reticulum for muscle contraction.
What do impulses that move down the T tubules most directly cause?
Impulses that move down the T tubules most directly cause the release of calcium ions from the sarcoplasmic reticulum in muscle cells. This calcium release triggers muscle contraction by interacting with the contractile proteins within the muscle fibers.
What is the function of the transverse tubules in muscle activation?
Transverse tubules are extensions of the cell membrane that allow action potentials to quickly penetrate into the interior of muscle cells. This helps in triggering the release of calcium ions from the sarcoplasmic reticulum, which is essential for muscle contraction.
How many t tubules in a muscle cell?
A muscle cell, or myocyte, typically contains a network of T tubules that are organized around the myofibrils. Each muscle cell has two T tubules per sarcomere, which correspond to the A-I junctions of the sarcomeres. Therefore, the total number of T tubules in a muscle cell depends on the number of sarcomeres present, which can vary widely among different muscle types and sizes. In general, a typical skeletal muscle fiber can have hundreds to thousands of T tubules.
What prevents calcium reabsorption?
Calcium reabsorption in the kidneys can be inhibited by several factors, including high levels of parathyroid hormone (PTH) or calcitonin, which regulate calcium balance. Additionally, certain diuretics, particularly loop diuretics, can decrease calcium reabsorption in the renal tubules. Conditions like hypercalcemia or the presence of specific medications can also interfere with calcium reabsorption. Overall, hormonal regulation and the impact of various substances are key in modulating calcium retention in the body.
Do Smooth muscle cells have t tubules?
no. Only skeletal and cardiac muscles have T tubules.
How do t-tubules contribute to the excitation-contraction coupling process in skeletal muscle?
T-tubules are invaginations of the cell membrane in skeletal muscle fibers that help transmit electrical signals deep into the muscle cell. This allows for the coordinated release of calcium ions from the sarcoplasmic reticulum, which triggers muscle contraction. In essence, t-tubules play a crucial role in linking the electrical stimulation of the muscle cell membrane to the contraction of the muscle fibers.
Do t tubules play a role in storing calcium within muscle cells?
Yes, T-tubules play a role in storing calcium within muscle cells by helping to facilitate the release of calcium from the sarcoplasmic reticulum during muscle contraction.
Cardiac muscle cells are like skeletal muscle cells in that?
Cardiac muscle cells are similar because they have striations which are strands of actin and myosin filaments. They also have mitochondria, transverse tubules, and sarcoplasmic reticulum.Cardiac muscle is different from skeletal muscle in that the muscle is branching, with intercalated dicks at the ends of them, store less calcium, the transverse tubules are larger, and their twitches are longer. Also, the entire cardiac muscle contracts as a whole, regulates itself, and is rhythmic.
What does sarcoplasmic reticulum do?
The Sarcoplasmic Retiulum releases calcium ions that will cause troponin/tropomyosin complex to move. This exposes the binding sites on actin and allows the cross-bridges of myosin to bind to the actin binding sites.
What is the role of the tubules?
What is the function of the transverse tubules, is it the place where actin and myosin interact or the storage of calcium ions, or to transmit muscle impulses into the cell interior?
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.
What are calcium ions stores as in muscle cells?
sarcoplasmic reticulum, i think. either that are T tubules
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.
What period is characterized by calcium ions release into cytosol and depolarization of the sarcolemma and T tubules?
The period that would be characterized by those things would be muscle contraction. Calcium ions are the neurotransmitters that cause contraction. Calcium Ions depolarize the cell and are spread through out the muscle via the T tubules.
Is clacium freely moving through the syctoplasm in a resting skeletal muscle?
It's stored inside the longitudinal tubules of the sarcoplasmic reticulum.
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.
