Question

31. What is required in Endochondral Ossification?

A. Hyaline Cartilage.

B. Fibrous Connective tissue.

C. Elastic connective tissue.

D. Dense irregular Connective Tissue.

E. myofiber. 

 

32. The refractory period is the time:

A. between stimulation and the start of contraction.

B. when the muscle is shortening.

C. when the muscle is lengthening.

D. following a stimulus during which a muscle cell cannot respond to another stimulus.

E. it takes for acetylcholine to cross the synaptic cleft.

 

33. Fused tetanus is:

A. a pathological condition in which stimulation of one muscle triggers contraction of all others in the same motor unit.

B. a sustained contraction with partial relaxation between stimuli.

C. a sustained contraction in which individual twitches cannot be discerned.

D. a brief contraction of all the fibers in a motor unit.

E. a phenomenon that occurs in only muscle cells without refractory periods.

 

34. A motor unit is:

A. all the muscles that act as prime movers for a particular action.

B. the sarcomeres in an individual myofibril.

C. all of the neurons that stimulate a particular skeletal muscle.

D. a motor neuron plus all the skeletal muscle fibers it stimulates.

E. the quantity of neurotransmitter that is sufficient to stimulate muscle contraction.

 

35. The Z disc is the:

A. separation between sarcomeres.

B. area of a sarcomere where only thick myofilaments are found.

C. point where the axon and the sarcolemma meet.

D. place where two cardiac muscle cells meet.

E. electrical voltage at which a muscle cell fires an action potential.

 

36. The motor protein in all three types of muscle tissue is:

A. actin.

B. myosin.

C. tropomyosin.

D. titin.

E. nebulin.

 

37. The muscle protein whose function is related to its golf club-like shape is:

A. actin.

B. troponin.

C. tropomyosin.

D. myosin.

E. titin.

 

38. Which of the following conditions exists in a resting myofiber?

I. Levels of calcium ions are relatively high in the sarcoplasm.

II. Thin myofilaments extend across the H zone.

III. ATP is attached to myosin cross bridges.

IV. Levels of acetylcholine are high inside the sarcoplasmic reticulum.

                      A. I

                      B. II

                     C. III

                     D. IV

                     E. Both I and III are correct.

 

39. The protein responsible for much of the elasticity and extensibility of myofibrils is:

A. nebulin.

B. alpha-actinin.

C. titin.

D. troponin.

E. tropomyosin.

 

40. What is happening during the latent period of a muscle contraction?

A. nothing.

B. Calcium ions are being actively transported back into the sarcoplasmic reticulum.

C. New contractile proteins are being synthesized.

D. Calcium ions are beginning to enter the sarcoplasm from the sarcoplasmic reticulum.

E. ATP molecules are attaching to myosin heads.

Answer 1

31.  What is required in Endochondral Ossification?

Answer is HYALINE CARTILAGE. In endochondral ossification, bone develops by replacing hyaline cartilage.

Steps of endochondral ossification:-

1. Hyaline cartilage enlarges and chondrocytes die
2. Blood vessels grow into perichondrium, cells convert to osteoblasts, shaft gets covered with superficial bone
3. More blood supply and osteoblasts, produces spongy bone and formation spreads on shaft
4. Osteoclasts create medullary cavity; appositional growth
5. Epiphysis centers calcify; blood and osteoblasts move in; secondary ossification centers
6. Epiphysis filled with spongy bone; cartilage remains at joints; epiphyseal plate in metaphysis.

32. The refractory period is the time:

The answer is "following a stimulus during which a muscle cell cannot respond to another stimulus"

In physiology, a refractory period is a period of time during which an organ or cell is incapable of repeating a particular action, or the amount of time it takes for an excitable membrane to be ready for a second stimulus once it returns to its resting state following an excitation.

33.  Fused tetanus is:

The answer is "a sustained contraction with partial relaxation between stimuli."

Fused tetanus is when there is no relaxation of the muscle fibers between stimuli and it occurs during a high rate of stimulation. A fused tetanic contraction is the strongest single-unit twitch in contraction. When tetanized, the contracting tension in the muscle remains constant in a steady state.

34.  A motor unit is:

The answer is "a motor neuron plus all the skeletal muscle fibers it stimulates."

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals. Groups of motor units often work together to coordinate the contractions of a single muscle; all of the motor units within a muscle are considered a motor pool.