B3 Muscle Tissue BIOLOGY

What are the key structural features of skeletal muscular tissue?

Muscle fibers, multi-nucleated, striated appearance, myofibrils, sarcomere, sarcolemma, sarcoplasmic reticulum, mitochondria, neuromuscular junctions, T tubules.

What is the function of sarcoplasmic reticulum in muscle cells?

Important in transmitting electrical impulses and storing calcium ions.

Define sarcomere.

A structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.

What role do calcium ions play in muscle contraction?

They bind to troponin, causing a shape change that allows tropomyosin to move and expose binding sites on actin for myosin heads.

What is the difference between slow twitch and fast twitch muscle fibers?

Slow twitch fibers are more efficient at using oxygen for sustained contractions, while fast twitch fibers contract quickly and fatigue rapidly.

How is the sliding filament theory related to muscle contraction?

It describes how actin and myosin filaments slide past each other to shorten the sarcomere, leading to muscle contraction.

What happens during muscle relaxation when stimulation ceases?

Calcium ions are pumped back into the sarcoplasmic reticulum and troponin and tropomyosin return to their original positions, relaxing the muscle fiber.

What are myofilaments?

Proteins that allow muscles to contract; they include actin and myosin.

What characterizes the A-band and I-band in skeletal muscle fibers?

A-band is the darker band representing regions of overlapping actin and myosin, while I-band is the lighter band with no overlap, containing only actin.

What is the role of ATP in muscle contraction?

It provides energy for the myosin head to move, bind to actin, and pull the filament during contraction.