Locomotion and Movement

Calcium is important in skeletal muscle contraction because it

1. detaches the myosin head from the actin filament
2. binds to troponin to remove the masking of active sites on actin for myosin
3. prevents the formation of bonds between the myosin cross bridges and the actin filament
4. activates the myosin ATPase by binding to it

Which of the following hormones can play a significant role in osteoporosis?

1. Estrogen and parathyroid hormone
2. Aldosterone and prolactin
3. Progesterone and aldosterone
4. Parathyroid hormone and prolactin

The pivot joint between atlas and axis is a type of

1. cartilaginous joint
2. synovial joint
3. saddle joint
4. fibrous joint.

Out of 'X' pairs of ribs in humans only 'Y' pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation.

1. X = 12, Y = 5; True ribs are attached dorsally to vertebral column and sternum on the two ends
2. X = 24, Y = 2; The true ribs are dorsally attached to vertebral column but are free on ventral side
3. X = 24, Y = 12; True ribs are dorsally attached to vertebral column but are free on ventral side
4. X = 12, Y = 7; True ribs are attached dorsally to vertebral column and ventrally to the sternum

Lack of relaxation between successive stimuli in sustained muscle contraction is known as

1. tetanus
2. tonus
3. spasm
4. fatigue.

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.