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Lecture 49
Sex Differentiation; Male Reproductive System
| Term | Definition |
|---|---|
| Chromosomes | 23 pairs,23 from mother (22 + x) 23 from father (x or y).carry genes,code for proteins |
| X and Y Chromosomes | x is female,xy is male.x chromosome is large,many genes.y chrom is small,few genes.sry gene starts male development in utero |
| Gonads in Embryo | gonads are the testes and ovaries.at 7th week,w/ sry,gonadal medulla leads to testes,cortex regresses.w/o sry,gonadal cortex leads to overies,medulla regresses. |
| Puberty | maturation of reproductive system.females:hair pattern,breast development and menstruation.males:hair pattern,erectile func,sperm,musculature. |
| Onset | inc gonadotropin rh (gnrh) release from hypothalamus necessary-kisspeptin stimulated.inc release of fsh and lh from pituitary.leptin from adipose tissue may be necessary for menarche. |
| Pituitary Gonadotropins | needs gnrh from hypothalamus for release.controlled by negative feedback of gonadal hormones:testosterone,estrogen,progesterone. |
| FSH | follicle stimulating hormone.females:growth and activation of ovarian follicles.males:develop and mature sperm by activating sertoli cells. |
| LH | lutenizing hormone.females:ovarian menstruation,estrogen secretion,ovulation.males:testosterone secretion from leydig cells. |
| Testes | seminferous tubules-sites of sperm production.sertoli cells-assist sperm production.leydig cells-testosterone production. |
| Spermatogenesis | formation of sperm cells from spermatocytes ~100,000,000 sperm/day. |
| Sperm Formation | spernatogonium mitosis-one stays,the other migrates inward.migrating cell,spermatocyte remodeled to sperm cell.sertoli cells absorb most of spermatocyte cytoplasm. |
| Sperm Structure | head-acrosome-digestive enzymes-nucleus-23 chrom.midpiece-mitochondia.tail-propulsion by microtuble rotation only needed near ovum. |
| Temperature | max sperm production at 32 c (body is 37 c)scrtoum will rise in cold and descend in heat to maintain temp.non-descended testicle usually sterile. |
| Semen | liquid holding sperm ~ 3 mil/ejaculate ~300,000,000 sperm. <20,000 sperm/ejaculate considered sterile.accessory structures contribute fructose,mucus,clotting proteins,bicarbonate to semen. |
| Erection | arteriole dilation,venous compression leads to engorgement.parasymp n. leads to NO production leads to arteriole vasodilation |
| Emission | mixing of prostattic fluid,sperm,and seminal vesicle fluid just prior to ejaculation.symp n. control emission. |
| Ejaculation | skeletal contraction expelling sperm. |
| Testosterone | steroid hormone.released in utero and shortly after birth to create male reproductive system.no further release until puberty.tonic release thereafter. |
| Secretion | from leydig cells as made.98% bound to protein in circulation.2% free and active.stimulates protein synthesis. |
| Secondary Sex Characteristics | male hair pattern-penile and genetalia enlargement.vocal cord thickening-inc mental activity. inc sex drive-inc growth. |
| Anabolic Effects | growth spurt,then epiphyseal closure.inc musculature and kidney size. |
| Inhibin | released from sertoli cells.inhibits fsh release.all hormones (fsh,lh,testosterone inhibin) are tonic and stable after puberty. |
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danamarie9323
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