Calcium ions are pumped back into the sarcoplasmic reticulum. A free ATP will come in and restore the myosin head back to 90 degrees preparing it again for another powerstroke. It's important to note that the myosin head does NOT hydrolyze the ATP. Only in a powerstroke it will hydrolyze the ATP to use the energy to bend the myosin head 45 degrees. If there is no free ATP to release the myosin head from it's bent angle then it remains rigid. That is why when a person dies their muscles stiffen because there are no free ATP to release the myosin heads from the actin filament.
G
Yes, calcium is necessary for the release of neurotransmitters that cause a muscle to initiate a contraction. Calcium is also needed to bind to the troponin-tropomyosin complex causing it to change position so the myosin head can attach to the actin molecule which results in contraction.
When Ca2+ ions are released from the sarcoplasmic reticulum, They combine with troponin, and this cause the tropomyosin threads to shift their position
It attaches to its receptor, and binds. Causes another action potential, (calcium released) and it goes to the T-tubule of the Sarcoplasmic reticulum, and attaches to troponin, which moves the tropomyosin, so the myosin and actin and attach, and cause a muscle contraction.
Hypocalcemia ( a low serum calcium level), not hypercalcemia ( a high serum calcium level), tends to cause muscle spasm and in severe cases may lead to muscle tetany.
too much calcium
Yes, when severe.
acetylcholine is broken down by enzyme acetylcholesterase, when it's supply is no longer renewed, a calcium pump removes calcium ions from the muscle fiber and returns them to the cisternae of the sarcoplasmic reticulum. Tropomyosin then blocks the linkage site and actin slides back to it's resting place.
slow down or will cause bradycardia. calcium is essential in muscle contraction.
Yes Calcium is vital for multiple process in the body. Calcium's main function is to strengthen bones. This is achieved through weight bearing exercises such as running or jumping which cause more calcium to be released. Calcium ions (Ca2+) play a vital role in muscle contractions as well. After ACH diffuses across the synaptic cleft Ca2+ binds to troponom which causes tropomyosin to move allowing actin and myosin to bind to form actomysosin. Calcium ions (Ca2+) are also used to speed up the heart in conjuction to hormones such as Epinephrine and Norepinephine. Brocholi is a particularly high in calcium
Low levels of calcium may cause cramping and muscle spasms. However, high levels of calcium may cause problems as well. Having the right amount of calcium in your diet may help treat spasms.
Depends on the cause - anything from sleep (or relaxing), to psychiatry, to calcium blockers, to muscle relaxants.
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.