Reproductive system

1. Part I: Intro and The hormonal control Reproductive system

2. Do you need an introduction? Connected series of organs and glands that are designed to produce and nurture sex cells and then transport them to the site of fertilization. Sex cells carry 23 chromosomes ( ½ a full complement) Male cells – sperm Female – oocytes (egg cells) Glands and organs secrete hormones and chemicals

3. It is a hormonal thing The development of the sexual characteristics is a hormonal thing The human body defaults to the female state if there is no testosterone available. This is why you can't tell gender until the third month. The testosterone hasn't produced enough to change the external genitalia.

4. Male hormonal Hypothalamus – produces gonadotropin-releasing hormone (GnRH) Goes to the anterior pituitary gland Anterior pituitary gland -produces luteinizing hormone (LH) (AKA interstitial cell stimulating hormone- ICSH) and follicale-stimulating hormone -FSH ICSH targets testicular interstitial cells and the adrenal cortex makes testosterone FSH – seminiferous tubules supporting cells to respond to testosterone to make sperm

5. Male sex hormones AKA Androgens Testicular interstitial cells make most Testosterone is most abundant Attaches to plasma proteins and is transported in the blood Secreted in fetal development until a few weeks after birth, and then is stopped until about 12-13 yrs old. It continues for the rest of the life Some males stop producing enough testosterone in the middle years Natural reduces during and after male climacteric (a decline in sexual functions associated with age)

6. What testosterone does for males... Enlargement of testes and accessory organs Development of secondary characteristics Increase growth of body hair, can slow hair growth on scalp Enlarges larynx and thickens vocal cords Thickening of skin Increase muscular growth, broadening of shoulders, narrowing of waist Thickening and strengthening of bones

8. A few more points Testosterone Increase cellular metabolism and red blood cell production Stimulates sexual activity by affecting portions of the brain The greater the amount of testosterone will determine the amount of development of the secondary characteristics Is part of a negative feed back loop

9. A minor but important player Estrogen New studies are linking it to sex drive and fertility Is typically made by converting testosterone Linked to bone mass retention Studies are just now beginning to study this hormone in depth in males.

10. On the ladies side Once again GnRH goes to work on the anterior pituitary gland LH and FSH is made in the anterior pituitary gland and goes to the ovaries to support the development of eggs and the production of female sex hormones. The adrenal cortex is also stimulated to make sex hormones Placenta secretes hormones during pregnancy

11. Primary hormone # 1 Estrogen is the most abundant made in ovaries (in non pregnant females) Responsible for the secondary sex characteristics Development of breast and ductile system of the mammary glands Increase deposition of adipose tissue in the subcutaneous layer generally and in the breast, thighs, and buttocks in particularly Increase blood vessels in the skin Enlargement of accessory organs Vagina, uterus, ovaries, and uterine tubes

13. Primary hormone #2 Progesterone – made primarily in the ovaries (except in pregnant females) Responsible for the changes in the uterus during the females cycle Affects the mammory glands Helps to regulate the secretion of LH and FSH

14. Not primary, but still important Androgen (the male sex hormone) Produced in the adrenal cortex Responsible for increased hair growth in pubic areas and axillary regions Lower amounts allow for narrow shoulders and broad hips Linked to sexual desire