MUSCLE PHYSIOLOGY

Detailed explanation-1: -Figure 38.18. 1: Muscle contraction: Calcium remains in the sarcoplasmic reticulum until released by a stimulus. Calcium then binds to troponin, causing the troponin to change shape and remove the tropomyosin from the binding sites. Cross-bridge cling continues until the calcium ions and ATP are no longer available.

Detailed explanation-2: -Ca2+ binds with the protein participating in muscle contraction to induce muscle contraction and is then reabsorbed into the sarcoplasmic reticulum via Ca2+ ATPase.

Detailed explanation-3: -Troponin and tropomyosin are indispensable for the physiological regulation of striated muscle contraction. The reason why troponin is essential is straightforward to understand, because it binds calcium ions19) and changes its structure with Ca2+.

Detailed explanation-4: -Contraction of heart muscle is driven by an interaction between myosin, actin and MgATP that is controlled on a beat-to-beat basis by transient binding of Ca2+ ions to the troponin/tropomyosin complex in the actin-containing thin filaments (Tobacman, 1996; Gordon et al.