Arteries usually carry oxygenated blood away from the heart. However, the pulmonary artery carries deoxygenated blood. If a defect occurs in this artery, then the possible effect will be on the supply of deoxygenated blood to the . Similarly, a defect in pulmonary veins may lead to a block in the supply of oxygenated blood to the .

Many birth-control pills release a constant amount of synthetic estradiols and progesterone for 21 days, followed by 7 days when no hormones are ingested. which of the following statements most accurately describes the effects of birth-control pills? -birth-control pills maintain constant levels of estrogens and/or progesterone so there is no surge in lh and ovulation does not occur.-birth-control pills inhibit the development of the uterine lining so implantation of a fertilized oocyte cannot occur.-birth-control pills maintain constant levels of estrogens and/or progesterones and mask the release of the oocyte from the follicle.-the 7 days with no hormones does not allow a thick enough uterine lining to form so a fertilized oocyte cannot implant.