Muscular System: Sarcomere

What is a primary function of the muscular system related to movement?

Enables voluntary and involuntary movements of the body.

What role does the muscular system play in maintaining body posture?

Maintains body posture and stability.

How does the muscular system contribute to heat production?

Generates heat through muscle contractions to help maintain body temperature.

What function does the muscular system serve related to joint stability?

Provides support and stability to joints during movement.

How do muscles assist in circulation?

Aids in the circulation of blood through the contraction of cardiac and smooth muscles.

What is the role of muscles in respiration?

Facilitates breathing by enabling the contraction of respiratory muscles.

What are the three main connective tissue layers surrounding skeletal muscles?

Epimysium, Perimysium, Endomysium.

What is the function of the epimysium?

The outermost layer encasing the entire muscle and continuous with a tendon.

What is the perimysium?

The intermediate layer that surrounds a fascicle, which is a bundle of muscle cells.

What does the endomysium surround?

The plasma membrane of a muscle cell.

What are muscle cells and muscle fibers?

Interchangeable terms referring to the same structure.

What do myoblasts fuse to form?

Long, cylindrical, multinucleate muscle fibers.

How long can some muscle fibers reach?

Lengths of up to 30 cm.

What is the plasma membrane of muscle cells called?

Sarcolemma.

What are the inner contents of muscle cells referred to as?

Sarcoplasm.

What is the role of transverse tubules in muscle fibers?

They enable signals from the nervous system to enter the sarcoplasm, initiating muscle contraction.

What is a sarcomere?

The structural and functional unit of a muscle fiber that contributes to muscle contraction.

What does the Z disc do?

Serves as an anchoring protein for thin filaments and delineates the boundaries of a sarcomere.

What are A bands?

Dark bands containing thick myosin filaments that overlap with thin actin filaments.

What characterizes I bands?

Light bands composed solely of thin actin filaments.

What is the M line in a sarcomere?

A dark band at the center of the H zone, composed of anchoring proteins.

What is titin?

An elastic protein that connects the thick filaments of neighboring sarcomeres.

What initiates the contraction of muscle fibers?

Arrival of Action Potential and Calcium release.

What happens during active site exposure in cross bridge cycling?

Calcium binds to troponin, causing a shape change that exposes active sites on actin.

What is formed when myosin binds to actin?

A cross bridge.

What occurs during the power stroke?

Myosin heads pivot, pulling actin filaments toward the center of the sarcomere.

What happens during cross bridge detachment?

Myosin detaches from actin after ATP binds to the myosin head.

What is involved in myosin reactivation?

The hydrolysis of ATP, which energizes the myosin head for the next cycle.