Question

(a) List two reasons that make copper releasing IUDs as effective contraceptives.
(b) Explain how the intake of oral contraceptive pills prevent pregnancy in humans.

Hint:

Copper IUDs work locally by affecting sperm and the uterine environment, while oral contraceptives act hormonally to suppress ovulation and alter reproductive conditions.

Answer 1

Step 1: For (a), two reasons copper-releasing IUDs are effective contraceptives are: (i) Copper ions released by the IUD are toxic to sperm, reducing their motility and viability, thus preventing fertilization. (ii) The IUD causes a local inflammatory response in the uterus, creating an environment hostile to implantation of a fertilized egg.
Step 2: For (b), oral contraceptive pills contain synthetic hormones (estrogen and progesterone) that mimic pregnancy conditions. They inhibit the release of GnRH from the hypothalamus, preventing the secretion of FSH and LH from the pituitary, which stops ovulation. Additionally, they thicken cervical mucus, making it harder for sperm to reach the egg, and alter the uterine lining to prevent implantation.
Thus, copper IUDs prevent fertilization and implantation, while oral pills prevent ovulation and create barriers to fertilization.