Female Reproductive System Lesson 10
Learning Goals 1. What are the five hormones involved in the female reproductive system? 2. Understand the four phases of the menstrual cycle.
Human Reproductive System
Female Reproductive System
Female Anatomy Ovaries produce hormones estrogen and progesterone Site of egg development and ovulation Fallopian tubes (oviducts) carry ovum from ovary to uterus Uterus organ where fetus develops Cervix separates vagina from uterus Vagina provides a passage for sperm and menstrual flow
Oogenesis and Ovulation Oogenesis production of an egg Ovaries contain small groups of cells called follicles Follicles contain the egg and secrete estrogen During ovulation, the oocyte is released Follicle cells turn into the corpus luteum
Female Hormones Estrogen steroid hormone Maintenance of female reproductive system Development of secondary sex characteristics (e.g. breast development, the growth of body hair, the widening of the pelvis, and the development of the sex drive) Progesterone steroid hormone Controlled by LH and FSH Prepares uterus for implantation of fertilized egg
Menstrual Cycle Preparation for pregnancy 1. Flow phase day 1-5 2. Follicular phase - day 6-13 3. Ovulatory phase - day 14 4. Luteal phase - day 15-28
Flow Phase (1-5) Shedding of the endometrium lining marks the flow phase Tissue that lines the uterine wall Rich with blood vessels LH and FSH released by the anterior pituitary Stimulated by the hypothalamus (GnRH) FSH stimulates the egg to develop Forms a follicle Endometrium lining begins to grow again as the menstrual flow ceases
Follicular phase (6-13) FSH and LH cause development of follicles within ovary Estrogen is secreted Estrogen has a negative feedback effect on the anterior pituitary Inhibits the secretion of FSH
Ovulatory phase (14) Hypothalamus and pituitary gland releases a burst of LH to trigger ovulation (LH surge) Egg bursts from ovary Follicle à corpus luteum After ovulation, estrogen levels decline and progesterone levels rise Many PMS (premenstrual syndrome) symptoms can arise due to a higher than normal estrogen to progesterone ratio
Luteal Phase (15-28) Development of corpus luteum marks the luteal phase Corpus luteum produces estrogen and progesterone Progesterone stimulates endometrium and prepares uterus for fertilized egg Inhibits ovulation and uterine contractions Corpus luteum degenerates if fertilization does not occur (due to low levels of LH) Estrogen and progesterone decrease Cause weak contractions à endometrium pulls away from the uterus (begin flow phase)
Pregnancy If fertilization occurs, the egg will implant and embryo will begin to release hcg (human chorionic gonadotropin) hcg keeps corpus luteum from breaking down Corpus luteum prevents menstruation from occurring and keeps estrogen and progesterone at high levels to maintain uterine lining and prevent menstruation
Hormonal Control Hypothalamus secretes GnRH signals puberty GnRH causes anterior pituitary to release FSH and LH FSH causes follicle to grow LH causes ovulation and maintenance of corpus luteum
Negative feedback High levels of estrogen inhibits release of FSH Positive feedback High levels of estrogen stimulates release of LH
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