Pharmacology Quiz: Hormonal Contraception!

FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are released in a pulsatile manner, meaning they are released in bursts or pulses rather than continuously. This pulsatile release is regulated by the hormone called gonadotropin releasing hormone (GnRH). GnRH is produced and released by the hypothalamus in the brain, and it stimulates the release of FSH and LH from the pituitary gland. Therefore, the correct answer is gonadotropin releasing hormone.

Gonadotropin releasing hormone is released from the hypothalamus to work on the pituitary gland to release LH and FSH.

Follicle stimulating hormone (FSH) is responsible for the increase in production of estrogen. FSH stimulates the growth and development of ovarian follicles in females, which then produce estrogen. Estrogen is a hormone that plays a crucial role in the development and regulation of the female reproductive system, including the growth of the endometrium, the development of secondary sexual characteristics, and the regulation of the menstrual cycle. Therefore, FSH indirectly stimulates the production of estrogen in the body.

During the luteal/secretory phase, the ruptured follicle transforms into a corpus luteum, which is responsible for producing progesterone. Progesterone plays a crucial role in preparing the uterus for implantation of a fertilized egg and maintaining pregnancy. It helps in thickening the uterine lining, inhibiting uterine contractions, and promoting the development of blood vessels. Therefore, progesterone is the hormone produced during the luteal/secretory phase.

Oral contraceptives work by reducing sperm transport in the upper genital tract, changing the endometrium to decrease the likelihood of implantation, thickening cervical mucus, and suppressing the HPA axis. These mechanisms collectively contribute to the effectiveness of oral contraceptives in preventing pregnancy.

FSH and LH

The correct answer is the follicular phase. This is the phase in the menstrual cycle where the uterine endometrium starts to thicken and proliferate in preparation for potential implantation of a fertilized egg. It occurs during the first half of the cycle, approximately from days 1 to 14. The luteal phase, on the other hand, occurs after ovulation and is characterized by the development of the corpus luteum. The shedding of the endometrium refers to the menstrual phase, which occurs if fertilization does not occur and the thickened lining is shed. Therefore, the correct answer is the follicular phase.

Mifepristone (RU-486) is a progesterone receptor antagonist. It works by binding to the progesterone receptors and blocking the effects of progesterone. This leads to the inhibition of progesterone's actions, including the maintenance of pregnancy. As a result, mifepristone can be used for medical abortion, as it causes the detachment of the embryo from the uterine wall and induces contractions to expel the pregnancy. Additionally, mifepristone has other uses, such as in the treatment of certain hormone-dependent tumors and for cervical ripening prior to surgical abortion or induction of labor.

The correct answer is chorionic gonadotropin. Pregnancy tests detect the presence of this hormone in a woman's urine or blood. Chorionic gonadotropin is produced by the developing placenta after implantation occurs. Its levels rise rapidly in the early stages of pregnancy and can be detected by the test. Elevated estrogen and progesterone levels are also associated with pregnancy, but they are not specifically targeted by pregnancy tests. Luteinizing hormone and gonadotropin-releasing hormone are involved in the menstrual cycle and ovulation, but they are not directly related to pregnancy.

LH (luteinizing hormone) is responsible for triggering ovulation and the formation of the corpus luteum. The corpus luteum is a temporary endocrine structure that forms from the ruptured follicle after ovulation. It secretes hormones such as estrogen and progesterone, which are crucial for preparing the uterus for possible implantation of a fertilized egg. FSH (follicle-stimulating hormone) is not secreted by the corpus luteum; instead, it is responsible for stimulating the growth and development of follicles in the ovary. Therefore, the correct answer is FSH.

The LH surge that occurs midcycle causes a series of events in the female reproductive system. It leads to follicular rupture, which is the release of a mature egg from the ovary. This is known as ovulation. Additionally, the LH surge slows down estrogen synthesis, which helps prepare the body for pregnancy. Finally, it stimulates progesterone synthesis, which is necessary for the maintenance of the uterine lining and the support of a potential pregnancy. Therefore, all of the given options are correct.

During midcycle, the sustained peak estrogen levels cause a reversal in the feedback loop, leading to positive feedback. This positive feedback stimulates the release of LH (luteinizing hormone), which plays a crucial role in ovulation. LH surge triggers the release of the mature egg from the ovary, preparing it for fertilization. Therefore, LH is the hormone predominantly released in response to the reversed feedback loop caused by high estrogen levels.

Intrauterine devices (IUDs) prevent pregnancies by changing the endometrium, the lining of the uterus, to make implantation of a fertilized egg less likely. This means that even if fertilization occurs, the fertilized egg will have difficulty attaching to the uterus and developing further. This mechanism of action makes IUDs highly effective in preventing pregnancies.

During the follicular phase, the developing follicle secretes estrogen, which has various effects on the female reproductive system. It stimulates the proliferation of the endometrium, preparing it for potential implantation of a fertilized egg. Estrogen also provides negative feedback to the anterior pituitary, reducing the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). However, estrogen does not directly cause follicular rupture. Instead, follicular rupture occurs during the ovulatory phase, when a surge in LH triggers the release of the mature egg from the follicle.

Oral contraceptives primarily work by decreasing the secretion of FSH (follicle-stimulating hormone) and LH (luteinizing hormone). These hormones are responsible for stimulating the release of an egg from the ovary (ovulation). By reducing the levels of FSH and LH, oral contraceptives prevent the maturation and release of an egg, thus preventing pregnancy. This mechanism of action is effective in preventing ovulation and is one of the main ways in which oral contraceptives work.

Clomiphene is an antiestrogen used for infertility that works by disrupting the negative feedback of estrogen in the hypothalamic-pituitary-ovarian (HPA) axis. This disruption leads to an increase in the release of gonadotropin-releasing hormone (GnRH), which in turn stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. This increased release of LH and FSH encourages the maturation of multiple follicles, increasing the chances of ovulation and pregnancy. Therefore, the correct answer is that clomiphene does not decrease LH and FSH, but rather increases their release.

If fertilization does not occur, the levels of estrogen and progesterone decrease abruptly because these hormones are primarily produced by the corpus luteum, which forms after ovulation. In the absence of fertilization, the corpus luteum degenerates, leading to a decrease in hormone production. Additionally, the sloughing or shedding of the endometrial lining occurs during menstruation, which is triggered by the decrease in hormone levels. However, the development of a new follicle is not affected by the absence of fertilization. The levels of LH and FSH, which stimulate follicle development and ovulation, respectively, also decrease when fertilization does not occur.

Luteinizing hormone stimulates the production of androgen and progesterone. Androgens are male sex hormones that are responsible for the development of male characteristics, such as facial hair and deepening of the voice. Progesterone is a female sex hormone that plays a crucial role in the menstrual cycle and pregnancy. Therefore, luteinizing hormone is responsible for increasing the production of both androgen and progesterone.