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The Reproductive System. Review of Endocrine System. Reproductive System. Gonads (testes and ovaries) are the organs that produce reproductive cells (sperm and eggs). Also, produce sex hormones.
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Reproductive System • Gonads (testes and ovaries) are the organs that produce reproductive cells (sperm and eggs). Also, produce sex hormones. • Sex hormones (ie, testosterone and estrogen) are the chemical compounds that control the development and function of the reproductive system. • The male and female reproductive cells are called gametes. • The fusion of a male and a female sex cell during a process called fertilization, produces a zygote.
Seminal Fluid • These vesicles provide the energy for movement of the sperm, produce a mucus-like fluid that contains the sugar fructose. • The prostate gland and Cowper’s gland also secrete mucus-like fluids, as well as an alkaline fluid to neutralize acids from urine in the urethra. • The combination of sperm cells and fluids is called semen.
Nervous System and Hormone production • The hypothalamus and the pituitary gland control the production of sperm and male sex hormones. • Negative-feedback systems ensure that adequate numbers of sperm cells and constant levels of testosterone are maintained. • The pituitary gland produces and stores the gonadotropic hormone, male follicle-stimulating hormone (FSH), and male luteinizing hormone (LH or ICSH). • At puberty, the hypothalamus secretes the gonadotropin-releasing hormone (GnRH) which activates the pituitary gland to secrete and release FSH and LH.
Hormonal control • GnRH from the hypothalamus acts on the anterior pituitary to release FSH and LH (causing the testes to begin producing sperm and to release testosterone) • Follicle Stimulating Hormone (FSH): causes the cells in the seminiferous tubules to produce sperm and the release of inhibin (which acts on the anterior pituitary to inhibit the production of FSH). • Luteinizing Hormone: causes the testes to release testosterone (promotes secondary sex characteristics and stimulate spermatogenesis)
Hormonal Control – Female System • Similar control as to the male system. • The beginning of GnRH production signals puberty which begins the release of FSH and LH. • Female FSH and LH regulate the control of hormones produced by the ovaries – progesterone and estrogen. • The workings of FSH and LH and estrogen and progesterone during the menstrual cycle enable it to run efficiently.
Hormonal production in the menstrual cycle (Day 1-5) • Hormones are involved at every stage of the menstrual cycle. • The pituitary gland produces FSH which starts the development of one egg in a follicle in one of the ovaries.
Production of estrogen – Follicular stage – Day 6-12 • The ovary produces estrogen which causes the repair of the lining of the uterus after the last menstruation. • As the follicle matures, it releases estrogen and some progesterone • The increase of estrogen, inhibits the release of FSH. • Estrogen also triggers a sudden release of GnRH which leads to an increase in LH—which triggers ovulation and an ovum is released.
Ovulation – thickening of uterus membranes – end of Follicular stage – Day 13-14 • In the uterus, progesterone, which is released by the newly erupted follicle, causes the lining of the uterus to get thicker ready for the fertilized egg. • The follicular cells, left within the ovary develops into the corpus luteum, which produces progesterone and some estrogen.
Development of corpus luteum – Luteal phase – Day 14-28 • Once the ovum is released, LH causes the follicle to develop into a corpus luteum, which secretes progesterone and some estrogen. • As progesterone and estrogen rise in the blood, FSH and LH are inhibited in their production. • If the egg is not fertilized, the corpus luteum degenerates, causing the decrease in production of progesterone and estrogen. • This decrease in the sex hormones causes the cycle to begin again with the production and secretion of FSH and LH. • The lining of the uterus breaks down and menstruation occurs by the shedding of the uterine lining (endometrium).
Sexually Transmitted Infections (STI) • A number of infections can be transmitted through sexual intercourse. The involvement of close physical contact and the exchange of body fluids causes this. • STIs may be caused by viruses, bacteria, and parasites. The greatest concern are those caused by viruses and bacteria. • The most common viral STIs are HIV/AIDS, hepatitis, genital herpes, and humanpapilloma virus (HPV) • The most common bacterial STIs are chlamydia, gonorrhea, and syphilis.