Male & Female Reproductive System

1. Male & Female Reproductive System Mr. Chapman Biology 30

2. Male Reproductive System The main function of the male reproductive system is to produce sperm. Males begin to produce sperm at puberty and continue throughout their lives.

3. Swimming for Your Life A sperm is a tiny package with a big responsibility – to fertilize the egg and create a human life. So that tiny package is loaded with “gear” for its important journey. A few facts: • Daily sperm production by a healthy man: • 10 million to 50 million • Contents of average ejaculation: 50 million sperm; 25 million moving; 20 million deformed • Maturation: 72 days • Average swimming speed of a sperm: • 8 inches per hour • Survival time in a woman: 2 to 7 days

4. Male Reproductive System Sperm production takes place in the testes. Each testicle produces millions of sperm. Testosterone and FSH stimulate the production of sperm. The testes are enclosed in a pouch called the scrotum.

5. Male Reproductive System The scrotum keeps the testes at a lower temperature then the rest of the body for production of sperm. When immature sperm leave the testes, they travel to the epididymis, where they mature and remain until expelled.

6. Male Reproductive System During sexual stimulation, the sperm travel to the vas deferens. It is here where semen is produced. Fluids from the prostate gland, the bulbourethral gland secrete fluids that help protect the sperm and allow them to move more easily. The seminal vesicle secretes fluids that help the sperm neutralize the acidity of the vagina.

7. Male Reproductive System During sexual arousal, semen flows from the vas deferens to the urethra. When ejaculation occurs, there is a muscle that closes off the bladder to prevent urine from mixing with semen.

8. Female Reproductive System The main function of the female reproductive system is to produce ova; egg cells. The female reproductive structures will begin to develop and mature during puberty where the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are released from the hypothalamus and pituitary gland. These hormones activate the development of the sexual characteristics.

9. Female Reproductive System Eggs cells are produced in the ovaries. The ovaries are located on either side of the uterus. When an egg is mature each month, it is released into the fallopian tubes. These tubes are about 10 cm long and extend from the ovaries to the uterus.

10. Female Reproductive System The egg will travel through the fallopian tube until it reaches the uterus. If the egg becomes fertilized it will attach to the wall of the uterus, where it will develop into an embryo. An unfertilized egg will be broken down and discarded.

11. The Uterus The uterus is about the size of a pear. It has three layers: an inner layer of epithelial, a middle layer of muscle and an outer layer of connective tissue. The lower end of the uterus is called the cervix. The cervix opens into the vagina, which is the birthing canal.

12. Egg Production & Menstruation At birth females have about 2 million eggs that are partially developed. Before puberty, most of the eggs will be broken down, and only about 400, 000 will be left. At puberty, an increase in FSH, will stimulate an egg to complete meiosis I. One larger cell is developed and the other smaller cell, called the polar body, is discarded.

13. Egg Production & Menstruation The larger cell will go through meiosis II after it becomes fertilized with a sperm cell. This cell develops into an egg, or ovum cell.

14. Follicles and Ovulation Each developing egg within the ovary is surrounded by a group of cells called a follicle. When the egg is ready to be released, the follicle ruptures and the egg breaks through the ovary wall. Ovulation is the release of the egg.

15. The Egg’s Travels After the egg leaves the ovary, it travels through the fallopian tube, where it can be fertilized by a sperm. Within 5-7 days the egg moves from the fallopian tube to the uterus. An unfertilized egg is discarded during menstruation.

16. Menstrual Cycle and Stages The menstrual cycle is a series of monthly changes within the reproductive system that includes producing and releasing an egg, and preparing the uterus to receive it. The cycle is approximately 28 days and involves three stages. The 3 phases are as follows: Flow phase Follicular phase Luteal Phase

18. Flow Phase Day 1 of the cycle is the beginning of the menstrual flow. During this phase the uterine lining detaches and is released, along with mucous, from the body.

19. Follicular Phase This phase lasts from about day 6-14 In the beginning estrogen is low. The hypothalamus releases hormones which activate the pituitary gland to release FSH and LH. This causes the egg and follicle to mature. Ovulation occurs at about day 16.

20. Follicular Phasing Continued... When the egg is developing, it causes estrogen to increase. An increase in estrogen leads to a thickening of the uterine lining. At estrogen levels keep increasing, this leads to an increase in the production of LH. The high levels of LH cause the follicle to rupture and release the egg.

21. Luteal Phase After ovulation, the follicle turns yellow, and is now called the corpus luteum. The corpus luteum releases estrogen and progesterone which causes the inhibition of LH. The high levels of progesterone cause the uterine lining to thicken. There is also an increase in the number of blood vessels, in preparation for an embryo. If an egg is not fertilized, then pituitary gland stops making FSH and LH. The corpus luteum breaks down, leading to the inhibition of progesterone and estrogen. The inhibition of all the hormones leads to the shedding of the lining. For most women the menstrual cycle lasts from pre-teen years until their mid 50s.