Locomotion and Movement

Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.

1. Calcium
2. Magnesium
3. Sodium
4. Potassium

Osteoporosis, an age-related disease of skeletal system, may occur due to

1. immune disorder affecting neuromuscular junction leading to fatigue
2. high concentration of Ca++ and Na+
3. decreased level of estrogen
4. accumulation of uric acid leading to inflammation of joints.

Which of the following is not a function of the skeletal system?

1. Production of body heat
2. Locomotion
3. Production of erythrocytes
4. Storage of minerals

Which of the following joints would allow no movements?

1. Synovial joint
2. Ball and Socket joint
3. Fibrous joint
4. Cartilaginous joint

Sliding filament theory can be best explained as

1. actin and myosin filaments do not shorten but rather slide past each other
2. when myofilaments slide past each other, myosin filaments shorten while actin filaments do not shorten
3. when myofilaments slide past each other actin filaments shorten while myosin filaments do not shorten
4. actin and myosin filaments shorten and slide past each other.

Glenoid cavity articulates

1. clavicle with scapula
2. humerus with scapula
3. clavicle with acromion
4. scapula with acromion.

Select the correct matching of the type of the joint with the example in human skeletal system.

1. Cartilaginous – Between frontal and parietal
2. Pivot joint – Between third and fourth cervical vertebrae
3. Hinge joint – Between humerus and pectoral girdle
4. Gliding joint – Between carpals

Stimulation of a muscle fiber by a motor neuron occurs at

1. the neuromuscular junction
2. the transverse tubules
3. the myofibril
4. the sarcoplasmic reticulum.

Select the correct statement with respect to locomotion in humans.

1. The vertebral column has 10 thoracic vertebrae.
2. The joint between adjacent vertebrae is a fibrous joint.
3. A decreased level of progesterone causes osteoporosis in old people.
4. Accumulation of uric acid crystals in joints causes their inflammation.

The H-zone in the skeletal muscle fibre is due to

1. the central gap between actin filaments extending through myosin filaments in the A-band
2. extension of myosin filaments in the central portion of the A-band
3. the absence of myofibrils in the central portion of A-band
4. the central gap between myosin filaments in the A-band.