Muscle Anatomy and Contraction Quiz

Muscle Fiber Structure

• The sarcoplasm of a muscle fiber contains myofibrils, mitochondria, sarcoplasmic reticulum, and transverse tubules.

Myofibril Structure

• A unit of myofibril is called a sarcomere.
• The M line bisects the A band in a myofibril.

Muscle Fiber Shape

• Muscle fibers are long, multinucleated, and cylindrical in shape.

Transverse Tubules

• Transverse tubules (T-tubules) are involved in the transmission of action potentials from the muscle fiber surface to the sarcoplasmic reticulum.

Longitudinal Tubules

• Longitudinal tubules are not found in muscle fibers; instead, smooth endoplasmic reticulum is present.

Z-line Function

• The Z-line marks the boundary of a sarcomere and acts as an anchor for the myofilaments.

H Band Composition

• The H band is composed of thick myofilaments (myosin).

Myofilaments

• There are two types of myofilaments found in a myofibril: thick myofilaments (myosin) and thin myofilaments (actin).

Test your knowledge on the physiologic anatomy of muscle, excitation contraction coupling, and the different types of muscle contractions. Dive into the composition of muscle fibers, the role of sarcolemma and sarcoplasm, and understand the mechanisms behind muscle contraction.