Why can't tetanus occur in the heart?
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 contraction.
d. The heart contracts with maximal force every beat so it is impossible to increase the strength of its contraction.
e. Vagal stimulation slows down the heart rate to prevent summation of contractions.
C
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A) fertilization and one trimester. B) two trimesters of 1 month each. C) three trimesters of 1 month each. D) two trimesters of 2 months each. E) three trimesters of 3 months each.
The region of the brain responsible for regulating muscle tone and coordinating skilled voluntary movement is the
a. vestibulocerebellum b. spinocerebellum c. brain stem d. cerebrocerebellum e. prefrontal area
During ejaculation, the sphincter at the neck of the bladder is opened to permit entry of sperm into the urethra
Indicate whether the statement is true or false
Which type of lymphocyte responds to multiple antigens?
A. Memory T-lymphocyte B. Cytotoxic T-lymphocyte C. Natural killer cell D. Plasma cell E. Memory B-lymphocyte