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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.
What is the physiology behind muscle cramps?
Muscle cramps occur when muscles contract involuntarily and do not relax. This can happen due to various reasons such as dehydration, muscle fatigue, or electrolyte imbalances. When a muscle cramps, the normal communication between the nerves and muscles is disrupted, causing the muscle to contract and stay contracted. This can lead to pain and discomfort until the muscle relaxes.
What is the role of ATP in muscle contraction and how does it contribute to the process?
ATP (adenosine triphosphate) is the energy source that powers muscle contraction. When a muscle needs to contract, ATP is broken down into ADP (adenosine diphosphate) and inorganic phosphate, releasing energy that is used to fuel the contraction process. This energy allows the muscle fibers to slide past each other, generating the force needed for movement. In essence, ATP is essential for providing the energy needed for muscle contraction to occur.
When does wave summation occurs?
Wave summation occurs when a muscle is stimulated rapidly enough that it does not have time to completely relax between stimuli, causing the contractions to combine or "summate" to produce a stronger muscle contraction. This phenomenon can occur during repetitive or sustained muscle activity, leading to increased muscle force production.
