Female Reproductive System

Our Goals This Section... Identify and give functions for each of the following: ovaries (follicles and corpus luteum) oviducts (fallopian tubes) uterus endometrium cervix vagina clitoris Describe the functions of estrogen Describe the sequence of events in the ovarian cycle, with reference the follicular phase, ovulation, and the luteal phase Describe the sequence of events in the uterine cycle, with reference to menstruation, the proliferative phase, and the secretory phase Describe the control of the ovarian and uterine cycles by hormones including gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone

Structures Ovaries – location of egg production Ova (ovum) - eggs Oviducts Uterus Vagina Eggs and urine follow separate tracts in the female body

Oogenesis Ova development Several hundred thousand ova exist at birth in the ovaries Cortical region of follicles of ovaries After puberty these ova mature at the rate of once a month Just a few hundred develop over a lifetime

Oogenesis Follicles matures and goes through changes so that the ovum is now contained in the fluid-filled space Continues until the follicle bulges out from the ovary structure – GRAAFIAN FOLLICLE Ovulation – when the Graafian follicle bursts releasing the ovum Fimbriae direct the ovum to the oviduct Oviduct is lined with cilia that direct the ovum towards the uterus Follicular structure that is left behind develops into glandular tissue called the CORPUS LUTEUM

Thick-walled, muscular, pear-shaped organ Endometrium Uterus Thick-walled, muscular, pear-shaped organ Endometrium Inner lining of uterus with two layers Basal layer (adjacent to muscle & elastic fibers) Functional inner lining (thickness depends on reproductive cylcle) AKA Womb

Tube that extends from the cervix to the outside Vagina Tube that extends from the cervix to the outside Lined with mucosal cells Birth Canal Organ of copulation Clitoris is the female equivalent to the penis Labia – folds of skin that surround the vaginal opening

Hormonal Control FSH (follicle stimulating hormone) stimulates ovum maturation LH (luteinizing hormone) stimulates PROGESTERONE and ESTROGEN from the cells of the follicle Progesterone initiates the maturation of the endometrium lining

Estrogen Necessary for egg maturation Development of secondary sex characteristics Uterine cycle Fat and hair distribution Growth of the uterus and vagina Pelvic growth Breast growth (along with progesterone) Estrogen appears to have a negative feedback relationship with the anterior pituitary because the levels of LH and FSH decrease

Estrogen Then again when the follicle is mature and estrogen is at its highest there is a sharp increase in LH and an increase in FSH It is thought that estrogen has a positive feedback relationship with the hypothalamus – as the increase in LH causes ovulation

Corpus Luteum Follicular tissue that remains in the ovary after ovulation Secretes progesterone and estrogen Estrogen stimulates the thickening of the endometrium Progesterone stimulates the endometrium to become secretory This prepares the body for fertilization and pregnancy

Menstruation If fertilization doesn’t occur then the corpus luteum degenerates after approximately 10 days Estrogen and progesterone levels drop Endometrium that has built up is shed Menstruation Mainly blood AKA menses 5 days on average During menses the anterior pituitary begins to release LH and FSH and the cycle begins again