MNE 26- Sex Steroid Synthesis Exam Questions and Answers Latest update Rated A+

MNE 26- Sex Steroid Synthesis Exam Questions and Answers Latest update Rated A+ Weak Androgens and their characteristics - Answers DHEA -secreted in large quantities in male and female from adrenal cortex -have a low affinity to androgen receptors Strong Androgens and their characteristics - Answers Testosterone, Androstanediol, DHT -High affinity for androgen receptors -Testosterone is created in high levels and is a precursor to DHT Formation of DHT - Answers Testosterone + NADPH ==> DHT 5 alpha reductase (reduction of C4 double bond in testosterone) Enzymes and cofactors that catalyzes: Testosterone ==> Estradiol - Answers Aromatase, 3 NADPH, and 3 O2 Enzymes and cofactors that catalyzes: Testosterone ==> DHT - Answers 5-alpha-reductase + NADPH Enzymes and cofactors that catalyzes: DHT ==> Androstanediol - Answers 3-alpha-reductase In females, large amounts of testosterone is converted to what? - Answers Estradiol in the ovaries In males, large amounts of testosterone is converted to what? - Answers Estradiol in target tissue Regulation of Testosterone Synthesis - Answers GnRH release from HT ==> Secretion of LH and FSH from Ant. Pit. 1. LH act on Leydig cells to make testosterone 2. FSH and Testosterone act on Seritoli cells to produce Androgen Binding Protein (ABP) 3. ABP ensures very high levels of testosterone in testes for spermatogenesis -Testosterone will negatively feedback on Ant. Pit. and HT Sex Hormones must be carried by... - Answers TeBG -they are lipid soluble and must have a carrier protein -Testosterone can be carried by *Albumin* -Progesterone can be carried by *Croticosteroid binding globulin* (CBG) Testosterone affects... - Answers -Gonadotropin regulation -Spermatogenesis -Sexual Differentiation via Wolffian Activation (development of internal sexual structures) DHT affects... - Answers -sexual maturation at puberty -sexual differentiation via external virilization Presence of Testes Determining Factor (Tdy+) - Answers Causes development of Testes Testes release *Mullerian Inhibiting Factor* (MIF) which prevents development of a *uterus* Secretion of testosterone and DHT promotes development of internal and external sexual characteristics Absence of Testes Determining Factor (Tdy-) - Answers Causes development of Ovary Ovary will produce *estradiol* which induces development of external portions of the reproductive system Absence of *Mullerian Inhibiting Factor* stimulates development of upper reproductive system During early development, how do male and female sexual organs look? - Answers They are very similar, both having *genital folds* surrounding the *genital tubercle* Later in development...(males) - Answers In males, the penis grow from the *genital tubercle* and the *genital folds* close from the anus to the glans penis Urethra also migrates to the tip of the penis Later in development...(females) - Answers Genital folds do not fuse, but remain open forming the labia minora and majora *Genital tubercle* forms the clitoris Hypogonadism - Answers _Primary_ Inability to secrete testosterone via enzyme deficiency Depending on time of onset, can have total lack of secondary sexual characteristics _Secondary_ Defect in the secretion of *gonadotropins* from the pituitary which leads to testicular failure _Tx_ Androgen Cream 5-Alpha-Reductase Deficiency - Answers Inability to convert Testosterone to DHT Internal genitalia are male (controlled by Testosterone) External genitalia are female (lack of DHT) Complete Androgen Insensitivity Syndrome - Answers Complete CAIS (Testicular Feminization Disorder) No functional androgen receptors and therefore no response to androgens