1. Hormones Chemical substances - produced by endocrine glands - secreted into the blood - circulate throughout the entire body. - target tissues respond to hormones.

3. Target tissues

4. Hormones you are responsible for: Sex Hormones – Produced by the gonads: Androgens: Testosterone, Androstenedione, DHT,Androstenediol Estrogens: Estradiol, Estrone Progesterone Gonadotropins – Produced by the pituitary: Luteninizing Hormone (LH) Follicle Stimulating Hormone (FSH) Gonadotropin Releasing Hormone (GnRH) – Produced by the hypothalamus

5. Steroid Biosynthetic Pathway Pregnenolone Progesterone 17-OH Pro.. Androsteno- dione Testosterone Androsteno- dio l Dehydro… 17-Preg …. Cortiso…l Corticosterone EstradiolEstrone 11-Deoxy.. Deoxy…. Aldosterone 17-OH Cort Cholesterol 21-OH 11-OH Aromatase 21-OH 11-OH 3B-HSO CYP-17 Lyase 17B-HSO

6. What you need to know about the Steroid Biosynthetic Pathway 1.Cholesterol is the precursor to the all of the steroids. 2.Masculinizing and Feminizing hormones utilize the same biosynthetic pathway. No step in the pathway can be skipped. 3.Masculinizing and Feminizing hormones are very similar in size and chemical composition. 4.The main difference is that estrogens have aromatic rings.

7. Testosterone

8. Testosterone at Puberty

9. Estrogen at Puberty

10. Negative Feedback System Testes (Interstitial Cells Produce Testosterone) LHTestosterone Hypothalamus - Thermostat Pituitary Gland – Produces LH

12. Negative Feedback System Testes (Sertoli cells regulate sperm production) FSHSperm Hypothalamus - Thermostat Pituitary Gland – Produces FSH Ejaculation

13. Negative Feedback System Testes (Sertoli cells produce Inhibin) Stops FSH Inhibin – No sperm produced Hypothalamus - Thermostat Pituitary Gland – Produces FSH