Labor begins when the increasing concentration of ________, which stimulate(s) uterine contractions, reaches a point that overrides the effect of ________, which inhibit(s) uterine contractions.
A. relaxin; progesterone
B. estrogens; progesterone
C. progesterone; estrogens
D. relaxin; estrogens
Answer: B
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Kathryn is pregnant and very eager to breast-feed after the baby is born. Her friend gives her a supplement to encourage prolactin secretion and Kathryn starts to take it during pregnancy. The supplement works and Kathryn's blood level of prolactin increases. She does not begin lactating during pregnancy because
A. maternal plasma levels of prolactin are low during pregnancy. B. the high levels of estrogen and progesterone in maternal plasma inhibit the effects of prolactin. C. the breast ducts do not develop until after parturition. D. the low levels of circulating estrogen and progesterone during pregnancy inhibit milk synthesis by the breasts. E. high levels of androgens inhibit milk synthesis by the breasts.
Which of the following cartilage types has little ground substance and has a matrix dominated by collagen fibers?
A) fibrocartilage B) hyaline cartilage C) elastic cartilage D) reticular cartilage E) transitional cartilage
Which correctly describes the structure of an atom?
A. There are always the same number of protons and neutrons. B. There are always the same number of protons and electrons. C. There are always the same number of neutrons and electrons. D. The number of protons, neutrons, and electrons is always the same E. There are never the same number of neutrons and protons.
The majority of hydrogen ions generated in the formation of carbonic acid in the tissues are carried as freely dissolved H+ in the venous blood
Indicate whether the statement is true or false.