The Human Reproductive System

1. The Human Reproductive System * Body Parts and Functions

2. Female Reproductive System

3. Female Reproductive System

4. Female reproduction system • Fallopian tubes • Extend from the ovaries to the uterus • Carry the mature ova to the uterus • Inner walls with cilia which propel the egg to the uterus • Has two parts: fimbria and ampulla • Fimbria: envelopes the ovary and catches the egg at the time of ovulation (when egg is realesed) • Ampulla: Tube where fertilization takes place (when the sperm enters the egg)

5. 2. Uterus • The main reproductive organ (pear shaped) • Walls are 1cm thick, lined with tissue called uterine lining • Expandable • The site where the embryo is brought to maturity • Reforms each month in preparation of receiving a fertilized egg

6. 3. Vagina • Cavity that receives sperm and allows the passage of the fetus • Capable of considerable dilatation

7. 4. Ovaries • 4. Ovaries • There are two ovaries, which are almond shaped sacs 3cm x 2cm • Responsible for bringing ova to maturity • Contains the eggs, about 700 000 at birth • Between ages 12 to 50, about 400 eggs mature • Stops functioning at menopause.

8. Vulva (external glands) • Labia majora • Large external folds • Labia minora • Two folds that cover the vaginal opening. • Clitoris • Small, erectile structure with many blood vessels and nerve endings

9. Hyman • Membrane which covers the vaginal opening • Different forms, may be minimal or absent all together • Bartholian glands • Secretes a lubricating substance

10. Female Puberty • At the onset of puberty, the pituitary gland (in the brain) produces two hormones, FSH and LH • These hormones stimulate the ovaries to produce other hormones: estrogen and progesterone • These hormones produce a number of changes

11. Physiological Changes • Growth of body hair • Growth of breasts • Widening of hips • Development of genital organs • Beginning of menstruation

12. The Menstrual Cycle • The role of the menstrual cycle is to bring an egg to maturity so that it can be fertilized by a sperm. • Endometrium: • The lining of the inner surface of the uterus • A soft protection “bed” that supports and nourishes the embryo. • If the egg is not fertilized by a sperm, the lining is shed.

13. Four Phases • Phase 1 – The Menstrual Phase • Day 1 to Day 4-7 • Bleeding (release of the endometrium) to flush unfertilized eggs out of the system • Phase 2 – The Follicular Phase • Up to Day 14 • FSH (follicle stimulating hormone) is released from the brain in order to develop a new egg in the ovary • Follicle grows and releases estrogen. • The walls of the uterus also thicken (endometrium) in preparation of the possible arrival of a fertilized egg

14. Ovulation • Day 14 • A follicle releases an ovum into the Fallopian tubes • If fertilized, the egg will implant itself in the uterus • Phase 4 – Luteal Phase • Day 15 to Day 28 • Progesterone from ovary is released to maintain the endometrium until it is determined if the egg is fertilized. • The non-fertilized egg(s) degrades and hormonal changes lead to menstruation

16. Cowper’s glands

17. Male Reproductive System • Penis • Erectile organ that ejaculates semen during intercourse • Includes the glans (end of the penis) and foreskin (fold of skin around the glans) • Testicles (two) • About the size of egg yolks • Located inside the scrotum • Produce testosterone (hormone) and spermatazoa • The epididymis extends to form the vas deferens

18. Epididymis • Long tube about 6m in length coiled on top of each testicle • Vas deferens • Tubes connecting the testicles to the urethra • Collect sperm and store them between ejaculations • Seminal vesicles (two) • Produce a liquid that forms 30% of semen • Secretes a thick, transparent liquid into the vas deferens in which the sperms are suspended.

19. Ejaculatory duct • Connects the vas deferens to the urethra • Receives secretions from the seminal vesicles and sperm from the vas defrens. • Prostate • Produce a milky liquid that forms 60% of semen • Cowper’s glands • Produce a liquid that forms 5% of semen • Urethra • Extends from the bladder to the end of the penis • Receives urine from the bladder and sperm from the ejaculatory ducts

20. Male Puberty • At the onset of puberty, the pituitary gland (in the brain) produces two hormones, FSH and LH • These hormones stimulate the testicles to produce hormones called androgens (such as testosterone) • Androgens produce a number of changes, in addition to the production of spermatazoa

21. Spermatazoa

22. Physiological Changes • Growth of body hair • Deepening of voice • Development of muscle • Changes to genital organs

23. TWINS • Identical twins • 30% of all twins are identical • Develop from one egg & one sperm • The fertilized egg divides into two separate zygotes • These twins have the same sex, blood type & hereditary characteristics

24. Twins • Fraternal twins • 70% of all twins are fraternal • 2 eggs are released by one ovary or each ovary releases 1 egg • A different sperm fertilizes each egg • Different hereditary characteristics.

25. Procreation

26. Assisted Reproduction • Artificial insemination • Cryopreservation (freezing) • Sperm/egg donation • Fertility drugs • In vitro fertilization • Surrogacy

27. Ethical Issues • What to do with unused eggs and sperm… • Should surrogate mothers be paid for their “work”? • Should a child made by artificial insemination be allowed to find out who his/her “parents” are?