Hormone Regulation in Men

1. Hormone Regulation in Men

2. Spermatogenesis • Spermatogenesis is the maturation process of spermatozoa. Mature sperm are what is needed for sexual reproduction. These mature sperm are also referred to as male gametes. • The process must have the right conditions if healthy sperm are to be produced. When the conditions are not ideal, conceiving a child might be difficult or impossible. • The process begins at puberty and continues uninterrupted until death, unless there are medical conditions; however, as men age, the amount of sperm one can produce typically diminishes.

3. Spermatozoa, produced by males, contain a 23rd chromosome that is either an X chromosome (female) or Y chromosome (male), making each sperm cell either female or male. • Spermatozoa have a head that contains a nucleus, a mid piece that contains mitochondria, and a tail with its end piece. • Female spermatozoa have larger heads than their male counterparts, and are consequentially slower swimmers. • Spermatozoa “swim” by rotating a tail, which allows them to come into contact with the oocyte. One spermatozoan fertilizes the egg, thereby creating a zygote.

4. The Male Reproductive System • Testes: In the male reproductive system, sperm are produced in the seminiferous tubules of the testes. The testes also produce the male hormone testosterone and a portion of the seminal fluid, the liquid in which sperm are carried. • Scrotum: The testes are two organs contained in the scrotum, an external sac in the groin. The external location of the scrotum ensures the relatively low temperature that is necessary for the normal development of sperm. • Vas Deferens: After formation, the sperm pass from the testes into the tubular epididymis, and from there into another passage, the vas deferens.

5. Penis: The first stage of the male sexual act, erection, results from nerve impulses from the autonomic nervous system that dilate the arteries of the penis, thus allowing arterial blood to flow into erectile tissues of the organ. • Seminal Vesicle: The seminal vesicle, which produces the seminal fluid, and the prostate gland, which produces the prostatic fluid, are both connected to the ejaculatory duct leading into the urethra. • Semen: During sexual intercourse, the ducts in the testes, epididymid, and the ductus deferens cause sperm to be pushed into the urethra, and this mixes with the seminal and prostatic fluids. The Cowper’s glands also create mucus which is added to this fluid, forming semen. The semen travels through the penile urethra during intercourse.

6. Hormone Regulation in Women

7. Oogenesis • Oogenesis is the process whereby an ovum, or egg cell, is created and matures. Mature ova are what is needed for sexual reproduction. These mature ova are also referred to as female gametes or mature oocytes. • The process must have the right conditions if healthy ovum are to be produced. When the conditions are not ideal, conceiving a child may be difficult or impossible. • The process begins at puberty and continues uninterrupted until menopause, unless there are medical issues.

8. The Female Reproductive System • Ovary: There are two ovaries in the female, held in place on each side of the uterus by a membrane; each ovary is about the size of an almond. About 500,000 immature eggs are present in the ovary at birth. • Ovulation: Starting at puberty, eggs mature successively, and one breaks through the ovarian wall about every 28 days (known as ovulation or the ovarian cycle), which continues until menopause, or cessation of reproductive functioning in the female. • Ovum: The name for the egg which the ovary releases at least once every 28 days. • Fallopian Tubes: After its release from the ovary, the ovum passes into the oviduct (uterine or fallopian tube) and into the uterus.

9. Uterus: The human uterus is pear-shaped and about 3 in. (7.6 cm) long (it expands greatly during pregnancy); it normally lies in the pelvis, where it is supported by a ligament on either side extending to the pelvic wall. The body of the uterus tapers down to a necklike structure (cervix) that leads into the vagina. • Vagina: The vagina, a passage connecting the uterus with the external genitals, receives the penis and the sperm ejaculated from it during sexual intercourse. It also serves as an exit passageway for menstrual blood and for the baby during birth. • Vulva: These are the external genitals, including the clitoris (erectile tissue that responds to sexual stimulation), and the labia, which are composed of elongated folds of skin.

10. Fertilization • If the ovum is fertilized by the sperm, pregnancy occurs. The fertilized ovum travels from the fallopian tubes into the uterus, where it becomes implanted in the lining of that organ, also known as the endometrium. If fertilization does not occur, the ovum and the lining of the uterine wall pass out of the body through the vagina (during the menstrual cycle). Endometrial tissues then build up again in the uterus in anticipation of the next release of an ovum. • If the ovum is fertilized, and the embryo (fertilized ovum) implants in the tube, or another area outside the uterus, an ectopic pregnancy occurs. Surgery is required to remove the fetus.

11. Puberty • Puberty can take anywhere from one to six years to occur. There is no “right” time for it to start– each person is different. In girls, it typically starts between the ages of 9 to 14, while for the boys, it seems to start at 10 to 17. • What triggers puberty is the hormones that your brain is releasing. When your body gets closer to sexual maturity, the pituitary gland begins to release estrogen and progesterone for the girls and testosterone for the boys. This helps each gender’s reproductive organs to develop. • Your body also has growth hormones running through it. This affects your height, weight, and overall shape. Girls seem to get curvier, while boys tend to get more muscular and broad-shouldered. • Typical physical changes that both sexes see are hair growth, acne, change in voice, and sweating. • Hormones also affect the sexes in emotional ways. You may begin to overreact, be overly emotional, quick-tempered, depressed, or you may begin to experience mood swings that you haven’t had before. It’s important that if you start to feel as though you are losing control, you speak to a trusted adult or health care professional.