Vertebrate striated muscle contraction is controlled (regulated) by the action of the proteins troponin and tropomyosin on the actin filaments. Nervous stimulation causes a depolarisation of the muscle membrane (sarcolemma) which triggers the release of calcium ions from the sarcoplasmic reticulum.
n. 1  Abnormally fast or deep respiration, which results in the loss of carbon dioxide from the blood, thereby causing a fall in blood pressure, tingling of the extremities, and sometimes fainting.
Rapid heart beat is a symptom in which a person's heart is beating fast. A fast heart rate can be normal if a person is excited or exercising. Sometimes a rapid rate is called sinus tachycardia, atrial flutter, or atrial fibrillation, etc..., depending on the type of arrhythmia (heart rhythm or rate problem).