Why can't tetany of the heart occur?
a. there are no distinct motor units in the heart.
b. there is inadequate oxygen supply via the coronary circulation to metabolically support a sustained contraction.
c. the refractory period in cardiac muscle lasts almost as long as the duration of the resultant contraction.
d. the heart contracts with maximal force every beat so it is impossible to increase the strength of cardiac contraction.
e. vagal stimulation slows down the heart rate to prevent summation of contractions.
C
You might also like to view...
The striations seen in skeletal muscle consist of alternating dark bands, called the ____ bands, and light bands, called the ____ bands.
The presence of a recessive gene can be detected (seen) only if the individual is
A) homozygous recessive. B) heterozygous dominant. C) heterozygous recessive. D) homozygous dominant. E) epistatic recessive.
Identify the primary region of the ulna that forms the hinge joint with the humerus.
A. Trochlear notch B. Coronoid process C. Olecranon process D. Olecranon fossa
The coccyx is
A. absent in humans. B. also called the coxa. C. located in the upper lumbar region. D. the most inferior portion of the vertebral column. E. the bottom of the spinal cord.