L3 PT - Myofascial system

What is the outermost membrane that covers the whole muscle called?

• Perimysium

• Endomysium

• Epimysium

• Sarcolemma

Answer explanation

The outermost membrane covering the entire muscle is called the epimysium. It encases the muscle belly, while the perimysium surrounds bundles of muscle fibers, and the endomysium covers individual fibers.

Which proteins are found in the myofilaments necessary for muscle contraction?

• Actin and tropomyosin

• Myosin and troponin

• Actin and myosin

• Tropomyosin and sarcolemma

Answer explanation

The proteins necessary for muscle contraction are actin and myosin. Actin forms thin filaments, while myosin forms thick filaments. Together, they interact to produce muscle contraction through the sliding filament mechanism.

What is the function of the sarcoplasmic reticulum in muscle fibres?

• It is the muscle's cell membrane.

• It stores calcium for release on demand.

• It separates muscle fibers.

• It contains contractile proteins.

Answer explanation

The sarcoplasmic reticulum is crucial in muscle fibers as it stores calcium ions. Upon stimulation, it releases calcium, which is essential for muscle contraction, making 'It stores calcium for release on demand' the correct choice.

What are the smallest units of muscle contraction called?

• Myofibrils

• Sarcomeres

• Fasciculi

• Tendons

Answer explanation

The smallest units of muscle contraction are called sarcomeres. They are the repeating units within myofibrils that contract to produce muscle movement.

What is the role of tendons in the muscular system?

• They store calcium.

• They attach muscle to bone.

• They separate muscle fibers.

• They contain contractile proteins.

Answer explanation

Tendons play a crucial role in the muscular system by attaching muscles to bones, allowing for movement when muscles contract. This connection is essential for the skeletal system to function effectively.

What is the connective tissue that covers each muscle called?

• Perimysium

• Endomysium

• Epimysium

• Sarcoplasmic reticulum

Answer explanation

The connective tissue that covers each muscle is called the epimysium. It encases the entire muscle, providing support and protection, while the perimysium and endomysium cover bundles and individual muscle fibers, respectively.

What are muscle fibres made up of?

• Sarcomeres

• Myofibrils

• Myosin heads

• Actin filaments

Answer explanation

Muscle fibres are primarily made up of myofibrils, which are long, thread-like structures containing the contractile units called sarcomeres. Myosin heads and actin filaments are components within sarcomeres, not the fibres themselves.

Which proteins are involved in the sliding filament theory of muscle contraction?

• Tropomyosin and troponin

• Actin and myosin

• Collagen and elastin

• Keratin and fibrin

Answer explanation

The sliding filament theory of muscle contraction involves actin and myosin proteins. Actin filaments slide over myosin filaments, causing muscle contraction. Tropomyosin and troponin regulate this process, but they are not the primary proteins involved.

What is the role of myosin heads during muscle contraction?

• They anchor the sarcomere

• They attach to actin and rotate

• They form the sarcoplasmic reticulum

• They cover the muscle fiber

Answer explanation

During muscle contraction, myosin heads attach to actin filaments and rotate, pulling the actin closer and shortening the muscle. This process is essential for muscle movement, making 'They attach to actin and rotate' the correct choice.

What molecule provides the energy for the myosin head to bind with actin?

• Adenosine diphosphate (ADP)

• Adenosine triphosphate (ATP)

• Creatine phosphate

• Glucose

Answer explanation

Adenosine triphosphate (ATP) provides the necessary energy for the myosin head to bind with actin during muscle contraction. When ATP is hydrolyzed, it releases energy that facilitates this binding process.