anatomy muscle unit

In addition to producing skeletal movement, skeletal muscles contribute to thermoregulation primarily through which process?

Production of heat as ATP during muscle contraction

In skeletal muscle fibers, what role do the transverse tubules (T-tubules) play in muscle contraction?

They propagate the action potential into the cell

In a relaxed skeletal muscle fiber, what specific regulatory protein directly covers the myosin-binding sites on actin?

Tropomyosin

According to the sliding filament model of contraction, which of the following occurs within a sarcomere as a muscle fiber actively contracts?

The distance between Z-discs decreases while myofilaments length stays the same

Muscle fatigue is caused by

exhaustion of energy reserves and buildup of lactic acid levels

This protein covers the myosin-binding sites to prevent actin from binding to myosin. This protein is called

tropomyosin

The calcium ions involved in skeletal muscle contraction bind to a ________ subunit.

troponin

A power stroke involves

a myosin head pulling a thin filament toward the M-line

During which phase of a twitch in a muscle fiber is tension the greatest?

contraction phase

What type of muscle contraction occurs when the biceps brachii muscle brings the arm upward with increasing muscle tension?

concentric

Muscle contractions become continuous if the stimulus frequency is so high that the relaxation phase disappears completely. This process is known as

tetanus

In this phase, the Ca²⁺ ions in the sarcoplasm have bound to troponin, tropomyosin has shifted away from actin-binding sites, cross-bridges are formed, and sarcomeres are actively shortening to the point of peak tension. This phase is known as

contraction