PHYSIOLOGICAL ACTION OF TESTES

Testes are the male gonads which have dual function as they produce sperm and also produce some hormones.
The Hormones produced by Testes are collctively called Androgens
Main Androgen Hormone produced by Leydig cell of Testis is TESTOSTERONE, a steriod hormone its secretion is regulated by pituitary gland

1. PHYSIOLOGICAL ACTION OF TESTES SUBMITTED BY: Amir sohil SUBMITTED TO: Prof. N.K Agarwal

2. Testes-an Endocrine gland The Testes are the male gonads, or reproductive glands. When stimulated by the release of pituitary gonadotropins, these glands produce and secrete the hormones that control the development of male sexual characteristics and the reproductive function of the adult male

3. Hormones produced by Testis Testosterone Produced by: Leydig cells Regulation: GnRH from hypothalamus Causes LH secretion from the pituitary gland which stimulate the Leydig cells

4. Action This hormone controls and maintain the Growth and function of the reproductive organs.It enhances libido and for spermatogenesis.

5. 2) Inhibin: Produced by: sertoli cells Regulation: GnRH from Hypothalamus causes FSH secretion from pituitary gland which stimulate sertoli cell.

6. Action: Prevents Secretion of further FSH from the pituitary gland

7. 3)Oestradiol: Produced by sertoli cells Regulation: GnRH from the Hypothalamus causes FSH secretion from the  Pituitary Gland  which stimulates the Sertoli Cells.

8. Action Converted from testosterone, this hormone's function is complex. It may prevent apoptosis of male germ cells.

9. Testosterone –The chief Androgen Principal Androgen 7mg/day in young but secretion decreases with age Like other steriod hormone it is bound to plasma proteins A variety of cells, like brain cell, breast can convert testosterone into estradiol.

10. Testosterone secretion is under control of LH. Synthesized by cholesterol in the Leydig cells and also formed from androstenedione secreted by adrenal cortex.

11. Mechanism of action - Testosterone Penetrates the target cell Androgen Target cell convert Testosterone into 5 α - dihydrotestosterone(DHT) by 5 α reductase DHT and Testosterone bind to same intracellular receptor. Testosterone receptors-less stable than DHT

12. Two types of 5 α -reduct ase encoded by different genes in humans Type 1 –present in skin Type 2 genital skin the prostate and other genital tissue Testosterone Receptor complexes responsible for maturation of wolffian duct and male internal genitalia during development.

13. DHT receptor complexes are needed to form external genitalia. DHT receptor also primarily responsible for enlargement of postate gland and probably of penisas well as facial hair and the temporal recession of hairline

14. The Androgen Receptor belong ro subfamily of steriod hormones receptors. The Receptor has been cloned and its sequence is detemined. Gene for receptor-on Human X chromosome. Gene comprised of eight exons (A-H) coding for three specific functionalities.

15. N-Terminal –coded by Exon A. Its function not clearly defined but may optimize transactivation capability. DNA binding domain –encoded by exons B and C. 66-68 Amino acid sequence. This domain code for first and second zinc finger motifs.The first zinc finger -Receptor DNA recognition ,Second -Dimerization of two receptor molecules during their assosition with DNA. The Androgen binding C Terminal -252 amino acids encoded by exins D-H