3-17 True/False

Although creatine phosphate is found in all body cells, muscle cells are unique in the way they use it to create ATP.

False (Creatine phosphate is only found in muscle fibers (cells) and it is used to create ATP)

Fibrillation of the heart creates a rhythmic, predictable pattern of contractions.

False (Fibrillation is a rapid series of uncoordinated or irregular "twitches". In this case the heart is NOT contracting normally)

A "charley horse" (extreme muscle cramp) is an example of a tonic contraction.

False (It is a tetanic contraction)

Myoglobin is used as an energy source to generate ATP very rapidly when needed.

False (Myoglobin is a specialized protein found in muscle cells that binds oxygen in a way similar to hemoglobin)

All muscle fiber types are dark red in color due to the presence of abundant myoglobin and extensive blood supply.

False (Not all muscle fibers have abundant myoglobin and vascularity. "Fast twitch B" (fast glycolytic) fibers have less myoglobin and fewer blood capillaries and are therefore paler in color (whitish))

Sitting upright in a chair during a 2 hour lecture probably involves the use of more fast twitch than slow twitch muscle fibers.

False (Slow twitch fibers are better for sustained activity such as posture)

Fast glycolytic muscle fibers ("Fast twitch B") have the fewest number of mitochondria compared to other muscle fiber types.

True

When cellular oxygen is depleted during exercise, lactic acid will form in the muscle cells.

True (In the absence of oxygen, ATP production can continue through the formation of lactic acid in the muscle cell, allowing it to work a bit longer)

Flexing the elbow joint causes an isotonic contraction to occur.

True (Isotonic contractions create movement by shortening the muscles. Flexion is a type of movement)

Muscle cells are capable of storing oxygen for later use in ATP production.

True (Myoglobin does this)