The distance between 1 and 7 spans a sarcomere correspond the structure at B is covered by the perimysium.
<h3>What is the smallest contractile unit within skeletal muscle?</h3>
A sarcomere comprises the segment between two consecutive Z lines and is the contractile unit of the muscle fiber, as it is the smallest portion of the muscle fiber capable of contraction and distension.
In this case, the distance between points 1 and 7 has the smallest structure of a skeletal muscle and corresponds to figure B.
A<em> fish ladder</em> is also known as fish steps, fish pass or fishway.
It is built around waterfalls, dams and locks.
The purpose of building a fish ladder is to<em> facilitate the natural migration of diadromous fishes.</em>
A fish ladder helps the fish to pass through the barriers by leaping up or swimming through the low steps of the ladder and reach into the water on the other side.
Since, without the fish ladder the barriers will not allow the migration of fishes, it is essential to be built around the dams, waterfalls and locks.
