Understanding Muscle and Joint Function

What is the primary function of synovial fluid in synovial joints?

• To provide nutrients to the joint

• To lubricate the joint

• To strengthen the joint

• To connect bones

Answer explanation

The primary function of synovial fluid is to lubricate the joint, reducing friction between the articular cartilage of synovial joints during movement, which helps maintain joint health and function.

Which of the following is an example of an agonistic pair of muscles?

• Biceps and triceps

• Quadriceps and hamstrings

• Deltoids and pectorals

• Gastrocnemius and soleus

Answer explanation

The biceps and triceps are an agonistic pair of muscles because they work in opposition to each other. When the biceps contract to flex the elbow, the triceps relax, and vice versa, demonstrating their antagonistic relationship.

In the sliding filament model of muscle contraction, which protein binds to actin to form a cross-bridge?

• Myosin

• Tropomyosin

• Troponin

• Titin

Answer explanation

In the sliding filament model, myosin binds to actin to form a cross-bridge, enabling muscle contraction. Tropomyosin and troponin regulate this interaction, while titin provides structural support.

Which type of joint is characterised by a fluid-filled cavity?

• Fibrous joint

• Cartilaginous joint

• Synovial joint

• Ball and socket joint

Answer explanation

A synovial joint is characterized by a fluid-filled cavity called the synovial cavity, which allows for smooth movement between the articulating bones. This distinguishes it from fibrous and cartilaginous joints, which lack this feature.

What is the role of stretch receptors in the body?

• To detect changes in muscle length

• To detect changes in muscle tension

• To detect changes in joint position

• To detect changes in temperature

Answer explanation

Stretch receptors, also known as muscle spindles, primarily detect changes in muscle length. This feedback helps regulate muscle contraction and maintain posture, making the first answer choice correct.

Which of the following bones is part of the axial skeleton?

• Femur

• Humerus

• Sternum

• Scapula

Answer explanation

The sternum is part of the axial skeleton, which includes the skull, vertebral column, and rib cage. The femur, humerus, and scapula are part of the appendicular skeleton, which supports the limbs.

During muscle contraction, which ion is released from the sarcoplasmic reticulum to initiate the process?

• Sodium

• Potassium

• Calcium

• Magnesium

Answer explanation

During muscle contraction, calcium ions are released from the sarcoplasmic reticulum. This release is crucial for initiating the contraction process, making calcium the correct answer.

What is the primary function of the skeleton?

• To produce hormones

• To store energy

• To provide structure and support

• To regulate body temperature

Answer explanation

The primary function of the skeleton is to provide structure and support to the body, allowing for movement and protecting vital organs. Other options like hormone production and energy storage are not primary functions of the skeleton.

Which of the following is NOT a characteristic of synovial joints?

• They have a joint capsule

• They are immovable

• They contain synovial fluid

• They have articular cartilage

Answer explanation

Synovial joints are characterized by their mobility, allowing for a range of movements. Therefore, the statement 'They are immovable' is NOT a characteristic of synovial joints.

In the sliding filament model, what happens to the sarcomere during muscle contraction?

• It lengthens

• It shortens

• It remains the same length

• It disintegrates

Answer explanation

During muscle contraction, the sliding filament model describes how actin and myosin filaments slide past each other, causing the sarcomere to shorten. Therefore, the correct answer is that the sarcomere shortens.