Hormones

Chemical substances

- produced by endocrine glands

- secreted into the blood

- circulate throughout the entire body.

- target tissues respond to hormones.

Target tissues

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

Steroid Biosynthetic Pathway

Pregnenolone

Progesterone 17-OH Pro..Androsteno-

dioneTestosterone

Androsteno-diolDehydro…17-Preg….

Cortiso…lCorticosterone

EstradiolEstrone11-Deoxy..Deoxy….

Aldosterone

17-OH Cort

Cholesterol

21-OH

11-OH

Aromatase Aromatase21-OH

11-OH

3B-HSO 3B-HSO 3B-HSO 3B-HSO

CYP-17

CYP-17

CYP-17

Lyase

Lyase

17B-HSO

17B-HSO

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.

Testosterone

Testosterone at Puberty

Estrogen at Puberty

Negative Feedback System

Testes

(Interstitial Cells Produce Testosterone)

LH Testosterone

Hypothalamus - Thermostat

Pituitary Gland – Produces LH

Negative Feedback System Testes

(Sertoli cells regulate sperm production)

FSH Sperm

Hypothalamus - Thermostat

Pituitary Gland – Produces FSH

Ejaculation

Negative Feedback System Testes

(Sertoli cells produce Inhibin)

Stops FSH

Inhibin – No sperm produced

Hypothalamus - Thermostat

Pituitary Gland – Produces FSH