A rise in cytosolic Ca2+ triggers muscle contraction(part D) Sarcomere Myofibrils Sarcoplasmic reticulum Transverse tubule Plasma membrane Terminal cisterna of SR A rise in cytosolic Ca2+ triggers muscle contraction(part Il Step 1: An excitation signal travels along the efferent nervous pathways towards the muscle Qee Step 2: The excitation signal de-polarizes the cell membrane Step 3: The potential triggers the release of calcium into the sarcoplasmic matrix surrounding the filaments of the motor Step 4: This removes the hindrance( tropomyosin)for interactions between actin and myosin filaments through chemical. mechanical and electrostatic actions. Step 5: The stepping action of myosin along the adjacent actin filament causes the two to slide relative to each other reducing the length of the sarcomere, producing contraction. Step 6: Sequestration of calcium ions in the sarcoplasmic reticulum(ATP-dependent) switches the contraction activityA rise in cytosolic Ca2+ triggers muscle contraction (part I) 2+ Step 1: An excitation signal travels along the efferent nervous pathways towards the muscle. Step 2: The excitation signal de-polarizes the cell membrane. This allows spread of the action potential along the Step 3: The potential triggers the release of calcium into the unit. Step 4: chemical, mechanical, and electrostatic actions. Step 5: The stepping action of myosin along the adjacent Step 6: reticulum (ATP-dependent) switches the contraction activity off. A rise in cytosolic Ca triggers muscle contraction (part II) sarcoplasmic reticulum. sarcoplasmic matrix surrounding the filaments of the motor This removes the hindrance (tropomyosin) for interactions between actin and myosin filaments through actin filament causes the two to slide relative to each other, reducing the length of the sarcomere, producing contraction. Sequestration of calcium ions in the sarcoplasmic 5�