51) Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose?

A) neurons

B) cardiac muscle cells

C) skeletal muscle fibers

D) liver cells

E) erythrocytes

52) Which statement regarding “heat loss” is true?

A) Muscle activity does not generate heat.

B) Shivering in a cold environment results in higher levels of heat loss.

C) When skeletal muscles are contracting at peak levels, body temperature drops.

D) Heat loss is reduced when blood flow to the skin increases.

E) Muscle contractions play an important role in the maintenance of normal body temperature.

53) The term used to describe muscular growth in response to usage is

A) multiple sclerosis.

B) muscular dystrophy.

C) atrophy.

D) hypertrophy.

E) myopathy.

54) Fast fibers

A) have loosely packed myofibrils.

B) have a high concentration of myoglobin.

C) have many mitochondria.

D) have high glycogen reserves.

E) are about half the diameter of slow fibers.

55) “Anaerobic endurance”

A) is used during long, slow athletic activities.

B) is exemplified by contractions of fast muscle fibers.

C) is determined by the availability of carbohydrates, lipids, or amino acids for breakdown.

D) is the length of time a muscle can continue to contract while supported by mitochondrial activities.

E) does not promote muscle hypertrophy.

56) During activities requiring aerobic endurance,

A) glycogen and glycolysis are the primary sources of reserve energy.

B) amino acids are not broken down.

C) most of the muscle’s energy is produced in mitochondria.

D) fatigue occurs in a few minutes.

E) muscle hypertrophy often occurs.

57) Which of the following is true about red muscles?

A) Red muscles are slower than white muscles.

B) Red muscles have fewer mitochondria than white muscles.

C) Red muscles have fibers of greater diameter than those of white muscles.

D) Red muscles contain less myoglobin than white muscles.

E) Red muscles fatigue quickly.

58) A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more ________ in his or her leg muscles.

A) fast fibers

B) intermediate fibers

C) slow fibers

D) dark fibers

E) red fibers

59) Which of the following is an accurate characteristic of slow fibers?

A) Slow muscle tissue has a much less extensive network of capillaries than does typical fast muscle tissue.

B) Resting slow muscle fibers contain oxygen reserves.

C) Slow muscle tissue has a lower oxygen supply than does fast muscle tissue.

D) Slow muscle fibers contain fewer mitochondria than do fast muscle fibers.

E) Slow muscle fibers contain myoglobin, a globular protein, which binds sodium.

60) Nonstriated, involuntary muscle is

A) cardiac.

B) red skeletal.

C) smooth.

D) white skeletal.

E) intermediate skeletal.