The Physiology of the Female Reproductive System

Physiology of the Female Reproductive System Estradiol2 Oogenesis Ovarian Cycle Uterine (Menstrual) Cycle Hormonal Regulation of Female Reproductive Cycle Extrauterine Effects of Estrogens and Progesterone Female Sexual Response

Oogenesis Oogenesis starts with the process of developing oogonia, which occurs via the transformation of primordial follicles into primary oocytes, a process called oocytogenesis. Oocytogenesis is complete either before or shortly after birth in humans, and thus during the menstrual cycle primary oocytes complete maturation through further meiotic divisions. The first meiotic division is coordinated by hormones: follicle stimulating hormone (FSH), estrogen, luteinizing hormone (LH), and progesterone. The oocyte is arrested in cell division prior to the second meiotic division, which only occurs after fertilization.

The Process of Oogenesis Oogenesis is the process of meiosis specific to the production of oocytes, particularly the uneven distribution of cellular components, including organelles and matrix, during divisions.

Ovarian Cycle The ovarian cycle refers to the series of changes in the ovary during which the follicle matures, the ovum is shed and the corpus luteum develops. The follicular phase describes the development of the follicle in response to follicle stimulation hormone (FSH). As luteinizing hormone and FSH levels increase they stimulate ovulation, or the release of a mature oocyte into the fallopian tubes. In the luteal phase, the corpus luteum forms on the ovary and secretes many hormones, most significantly progesterone, which makes the endometrium of the uterus ready for implantation of an embryo. If implantation does not occur the corpus luteum will be degraded, resulting in menstruation. If implantation occurs then the corpus luteum is maintained.

Ovarian Cycle

Uterine (Menstrual) Cycle The uterine cycle includes the increase in the endometrium in preparation for implantation, and the shedding of the lining following lack of implantation, termed menstruation. Menstrual cycles are counted from the first day of menstrual bleeding. Endometrial thickening is stimulated by increasing amount of estrogen in the follicular phase. If implantation does not occur then progesterone and estrogen levels drop, which stimulates menstruation.

The Menstrual Cycle The menstrual cycle is controlled by the endocrine system, with distinct phases correlated to changes in hormone concentrations.

Female Sexual Response Responses specific to females include engorgement of several tissues including the nipples, vulva, clitoris, and vaginal walls. Further changes include changes to the shape of the vagina and the positioning of the uterus in the pelvis, as well as increases in blood pressure and heart rate. Experienced by males and females, orgasms are controlled by the involuntary or autonomic nervous system. There are age related changes in sexual responsiveness that may be associated with changes in estrogen.

Estradiol One of the estrogens produced in the human body, predominant during a woman's reproductive years.

Progesterone Belongs to the progestogen class of hormones and is the predominant one of the human body.

Which of the following is NOT part of female sexual response? A) arousal increases blood flow to nipples, vulva, and clitoris B) arousal levels peak as estrogen levels decline C) arousal may peak in orgasm: rhythmic muscular contractions

Which of the following is NOT a function of progesterone? A) progesterone affects sperm in the vaginal tract prior to fertilization B) progesterone withdrawal leads to menstrual bleeding C) progesterone elevation at parturition signals lactation to commence D) progesterone decreases maternal immune response to implantation