When blood flows through capillary beds, its flow is regulated. What structures allow blood to flow into the capillary beds?
a. sinusoids
b. one-way valves
c. fenestrations
d. precapillary sphincters
Answer: d. precapillary sphincters
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The region known as the primitive streak is the site of
A) migration of mesodermal cells to form the endoderm. B) endoderm formation. C) ectoderm formation. D) migration of ectodermal cells to form the mesoderm. E) amnion formation.
The female pubic arch differs from the male pubic arch to facilitate childbirth. When compared to the male, the female pubic arch can best be described as
A. narrower B. shorter C. taller D. wider
The activation of olfactory receptors requires that the odorant become immersed in:
A) mucus. B) cerumen. C) saliva. D) blood.
Which of the following is a difference between cardiac muscle and skeletal muscle?
a. Unlike skeletal muscle cells, cardiac muscle cells do not rely on an influx of calcium ions for depolarization. b. Unlike skeletal muscle, cardiac muscle does not use a sliding filament mechanism for contraction. c. Unlike skeletal muscle, cardiac muscle is not striated. d. Unlike skeletal muscle cells, cardiac muscle cells can be autorhythmic.