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.
Labored breathing is very familiar to runners. They call it the ventilatory threshold. Itâs that intensity of exercise above which your breathing becomes labored and you feel you just canât draw in as much air as your body wants. Every runner is experientially familiar with the ventilatory threshold.When you run easy you breathe easy. As your speed increases, your breathing deepens, but gradually.However, as you continue to increase your speed, suddenly it seems as if a switch is flipped and your breathing races off ahead of your legs.very runner is experientially familiar with the ventilatory threshold. When you run easy you breathe easy. As your speed increases, your breathing deepens, but gradually. However, as you continue to increase your speed, suddenly it seems as if a switch is flipped and your breathing races off ahead of your legs.