The normal pacemaker of the heart is located in
A) the Purkinje fibers.
B) the sinoatrial node.
C) the atrioventricular node.
D) the wall of the left ventricle.
E) both the left and right ventricles.
B
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The intestinal hormone that stimulates the pancreas to release a watery, bicarbonate-rich fluid is
A) enterocrinin. B) secretin. C) cholecystokinin. D) GIP. E) gastrin.
Polyspermy results in
A) twins. B) fetuses with different fathers. C) haploid individuals. D) chimeric adults. E) a nonfunctional zygote.
In the science fiction movie The Abyss, a diver is able to breathe while his head is immersed in a specially prepared liquid pumped into a water-tight helmet attached to a suit, thus allowing him to dive without an air tank and at greater depths than possible for scuba divers. Is this purely fiction, or is it at least theoretically possible? Explain, considering the nature of alveoli and alveolar
gas exchange. Assuming it is possible, describe the composition and nature of the liquid in terms of its oxygen pressure and concentration. What will be an ideal response?
Nodes of Ranvier lie between neurons
Indicate whether the statement is true or false