Cardiac muscle fibers will contract more forcefully when stretched (the more you fill it with blood the stronger the contraction) is known as

Cardiac muscle fibers will contract more forcefully when stretched (the more you fill it with blood the stronger the contraction) is known as

• A. Lumen
• B. Starling's Law of the Heart
• C. Tunica externa
• D. Tunica intima

Answer: (B)

Starling's Law of the Heart describes how the heart adjusts its force of contraction based on how much it is filled. When the ventricles fill with blood during diastole, the muscle fibers are stretched. This stretch moves the fibers toward their optimal length for actin-mosin cross-bridge interaction, so during systole they can generate a stronger contraction. As a result, a higher venous return leads to a stronger pump, helping to match the output of the heart to the amount of blood returning to it. The other terms refer to parts of blood vessels or their walls (lumen is the hollow interior, tunica externa and tunica intima are vessel wall layers) and do not describe the heart’s stretch-induced increase in force.

Starling's Law of the Heart describes how the heart adjusts its force of contraction based on how much it is filled. When the ventricles fill with blood during diastole, the muscle fibers are stretched. This stretch moves the fibers toward their optimal length for actin-mosin cross-bridge interaction, so during systole they can generate a stronger contraction. As a result, a higher venous return leads to a stronger pump, helping to match the output of the heart to the amount of blood returning to it. The other terms refer to parts of blood vessels or their walls (lumen is the hollow interior, tunica externa and tunica intima are vessel wall layers) and do not describe the heart’s stretch-induced increase in force.