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.
A rapid heartbeat, also called tachycardia, is a condition in which the heart is beating fast, generally more than 100 beats per minute for an adult. A rapid heartbeat can be normal, or it can result from a disease, disorder or other harmful condition.