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When muscle fibers are stimulated to contract, an electrical impulse travels along the muscle cell membrane, leading to the release of calcium ions from the sarcoplasmic reticulum. This release of calcium triggers the interaction between actin and myosin filaments, the proteins responsible for muscle contraction. The myosin heads attach to actin and pull, causing the muscle fiber to shorten and generate force. This process is known as the sliding filament theory of muscle contraction.
What else can I help you with?
Before a muscle cell can be stimulated to contract again what must occur?
Repolarization
When does muscle relaxation occur?
Muscle relaxation occurs when the muscle fibers stop contracting and return to their resting state after being stimulated.
What changes are thought to occur in the skeletal muscle to allow treppe to be observed?
This is known as wave summation. It is when the fibers of the muscles become stimulated before having a chance to relax completely.
What happens after the electricity reaches the muscles?
After electricity reaches the muscles, it triggers the release of calcium ions within the muscle fibers. This causes the muscle fibers to contract and generate force, allowing movement to occur.
What happens to muscles when they contract?
When muscles contract, they shorten and generate force, allowing movement to occur. This process is controlled by the nervous system and involves the sliding of protein filaments within the muscle fibers.
What is maximal tetanic tension?
When a muscle is applying a little bit of force, action potentials are triggering twitches in the muscle fibers. A skeletal muscle has many many muscle fibers, and a single fiber (cell) is either contracted or relaxed, it cannot get stronger or apply a fraction of its force. A muscle fiber and its connected neuron are called a motor unit When a muscle is applying a lot of force it is sending many action potentials at once, such that most of the fibers in a muscle are contracting at once. This effect is called motor unit recruitment When a muscle is "maxing out," it is sending waves of many action potentials in rapid succession, such that the whole muscle is stimulated again while the stimulated cells are still in the relaxing phase. This has the effect of not only reactivating the fibers in the relaxing phase, but also engaging more of the few cells that were left so that more total fibers contract. When the signals are received in rapid enough succession the total force of the muscle will eventually plateau. This is called unfused tetanus. If applied at an even greater frequency the fibers that are activated will stay activated so that no lag is seen between single fiber twitches. It is at this point that the fibers are all fused and the muscle has reached maximum tetanic tension (This can occur as an effect in patients with tetanus, hence the name)
Why does your arm shrink when you have a cast on it?
Muscle atrophy and loss of strength occur when a limb is immobilized in a cast because the muscles are not being used. Lack of movement causes the muscle fibers to decrease in size and strength as they are not being stimulated, leading to shrinkage of the muscles. Physical therapy and exercise are often necessary after the cast is removed to regain muscle strength and mobility.
If a muscle contracts and its fibers shorten is the contraction isometric?
No! It is isotonic. But if the muscle contracts and the fibers do not shorten because the load is greater than the force applied to it, it is isometric.
Irregular transverse thickenings of the sarcolemma?
Irregular transverse thickenings of the sarcolemma connect cardiac muscle fibers to neighboring muscle fibers. The gap junctions that occur with irregular transverse thickening of the sarcolemma allow the myocardium to contract as a single unit.
When an animal runs along the ground by flexing some of its muscles what causes its muscles to contract?
Muscle contraction in animals is primarily triggered by the nervous system, which sends electrical signals called action potentials to muscle fibers. These signals stimulate the release of calcium ions within the muscle cells, leading to the interaction of actin and myosin filaments. This interaction causes the muscle fibers to shorten and generate force, allowing the animal to run. Additionally, energy in the form of ATP is required for muscle contraction to occur.
Why does muscle contraction occur?
Muscle contraction occurs due to the interaction between actin and myosin filaments within muscle fibers. When a muscle is stimulated by a nerve impulse, calcium ions are released, triggering the binding of myosin heads to actin, forming cross-bridges. This interaction pulls the actin filaments closer together, shortening the muscle fiber and generating force. ATP provides the energy required for this process, allowing the myosin heads to detach and reattach for continued contraction.
What is the ability of a muscle to shorten and thicken when given proper stimulation?
The ability of a muscle to shorten and thicken when stimulated is known as muscle contraction. This process occurs when muscle fibers receive signals from the nervous system, causing the actin and myosin filaments within the muscle cells to slide past each other. This sliding mechanism leads to the overall shortening of the muscle, generating force and enabling movement. Proper stimulation, such as through nerve impulses or electrical signals, is essential for this contraction process to occur effectively.
