human sex test 2ppt notes

human sex test 2ppt notes - Chapter 5 Sex Hormones and...

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Chapter 5 Sex Hormones and Sexual Differentiation Sex Hormones Hormones are powerful chemical substances manufactured by the endocrine glands and secreted directly into the bloodstream. Most important sex hormones: Testosterone Estrogen Progesterone Sex Hormones in the Male Testosterone - masculinizing sex hormone. Follicle-stimulating hormone (FSH) - controls sperm production. Luteinizing hormone (LH) - controls testosterone production. Gonadotropin-releasing hormone (GnRH) - regulates the pituitary’s secretion of gonad-stimulating hormones. Sex Hormones in the Female Estrogen - brings about many of the changes of puberty. Progesterone Prolactin - stimulate secretion of milk by the mammary glands. Oxytocin - stimulates contractions of the uterus during childbirth. Prenatal Sexual Differentiation Sex chromosomes - transmit information to various organs on how to differentiate in the course of development. XX = female XY = male Prenatal Development of Gonads In the 7th week after conception, sex chromosomes direct gonads to begin differentiation. Male - undifferentiated gonad develops into a testis at about 7 weeks. Female - ovaries develop at around 10-11 wks. If SRY (sex-determining region, Y chromosome) is present, then testes differentiate and male development occurs. Prenatal Hormones and the Genitals In the female, Mullerian ducts turn into fallopian tubes, the uterus, and the upper part of the vagina.
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In the male, Wolffian ducts, supported by testosterone, turn into the epididymis, vas deferens, and ejaculatory duct. Descent of the Testes and Ovaries Ovaries and testes change shape and position as developmental changes take place. Testes travel from near the top of the abdominal cavity down into the scrotum via the inguinal canal. Cryptorchidism (undescended testes) occurs in 2% of all males. Brain Differentiation During the prenatal period, sex hormones act on the brain: If testosterone is present during fetal development, estrogen receptors in the hypothalamus become insensitive to estrogen. If estrogen is present, they become highly sensitive to levels of estrogen in the bloodstream. Homologous and Analogous Organs Homologous organs - organs in the male and female that develop from the same embryonic tissue. Analogous organs - organs in the male and female that have similar functions. Variables of Gender Chromosomal gender Gonadal gender Prenatal hormonal gender Prenatal and neonatal brain differentiation Atypical Prenatal Gender Differentiation Intersex (pseudohermaphrodite) - biologically a person’s gender is ambiguous. Congenital Adrenal Hyperplasia
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This note was uploaded on 04/27/2008 for the course BIO 50.230 taught by Professor Wassmer during the Fall '07 term at Bloomsburg.

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human sex test 2ppt notes - Chapter 5 Sex Hormones and...

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