mod 14 Flashcards
Reproductive system - function
- Pass on genes of individuals + maintain the species
Fetal development - gender determination
- Each cell has 23 chromosomes - this includes paid of sex chromosomes
- Sex chromosomes have large X chromosome + smaller Y chromosome
- All eggs have X, sperm can have X or Y
- Sex of baby determined at fertilization - sperm carrying X gets to egg = girl bc XX, sperm w Y gets there = boy bc XY
Fetal development of system - first 6 weeks
- First 6 weeks, male + female embryos have common (indifferent) gonads
- These will turn into testes or ovaries
- 2 sets of primitive reproductive tracts - mesonephric (Wolffian duct) and paramesonephric (mullerian duct)
- In males - 6-7 weeks - presence of Y turns indifferent gonads to testes
- In females - 9 weeks - XX are activated and ovaries develop
Mullerian, Wolffian
- In males - 7 weeks - testicular cells make Mullerian inhibiting hormone (MIH), which causes mullerian duct to regress
- Males - 9wks - testicular cells start to make testosterone - small surge is testosterone stims wolffian duct to develop into epididymis, vas deferens, seminal vesciles, and urethra + external male genitalia
- Female genetalia requires no hormonal control
- In females - sincel there is not mullerian inhibiting hormone, the mullerian duct develops into fallopian tubes, uterus, cervix, part of vagina
- Also since no testosterone produced in female fetus, wolffian duct regresses and external female genetalia develops
- Reproductive system functions
○ Males - make testosterone, produce sperm (spermatogenesis) and devlier it to vagina
○ Female - makes estrogen and progesterone, makes eggs, receives sperm, makes optimal conditions for fetus
- Male system - structure
○ External - penis, scrotum
○ Penis - urethra, glans penis, corpus spongiosum and corpus cavernosum
○ Scrotum has testes (where sperm + testosterone made)
○ After made, sperm kept in epididymis
○ In ejacualtion, sperm goes through ductus deference (vas deferens), mixes w fluid from seminal vesicles, passes through prostate, gets more fluid from bulbourethral (cowper’s) gland, enters urethra, passes out through penis
○ Testes has ~1000 coiled seminiferous tubules
○ After sperm formed in semi tubules ^^, sperm goes into epididymis, drains into vas defernes
○ Semi tubules have sertoli cells + developing sperm
○ Outside of semi tubule are leydig cells
- Male system each thing - function
○ Seminiferous tubules - site of spermatogenesis
○ Sertoli cells - reg spermatogenesis + maintain developing sperm cells (aka spermatogonia) + they make inhibin (hormone) secrete fluid that pushes immature sperm to epididymis and form blood-testis barrier (BTB)
○ BTB isolates developing sperm cells from blood so immune cells don’t attack them bc they’re diff
○ If BTB not developed properly, immune cells would attack + destry developing sperm = sterility
○ Leydig cells - in interstitial space btwn seminiferous tubules ; make testosterone
○ Epididymis - final maturation area + storage site for sperm
○ Vas deferens/ ductus - carries sperm from epididymis to ejaculatory duct, which drains into urethra
○ Seminal vesicles - give lots of fluid to semen during ejaculation - fluid is rich in fructose and enzymes, which helps maintain, nourish sperm
○ Prostate gland - secretes enzymes and fluid that help neutralize acid enviro of urethra and vag
○ Bulbourethral gland (cowper’s gland) - secretes fluid to neutralize pH and lubricate urethra and vag to create optimal enviro for sperm
○ Urethra - transports sperm during ejaculation + drains bladder during urination
- Spermatogenesis
○ When they begin puberty and start making testosterone, sperm production (spermatogenesis) begins
○ Spermatogonia (germ cells) have 46 chromosomes, divide by mitosis into 2 cells, one continues as spermatogonia and other develops into primary spermatocyte
○ Primary spermatocyte divides by meiosis into 2 secondary spermatocyte (1st meitoic division) and then 4 spermatid (2nd division)
○ While dividing, they are surrounded + nourished by Serotoli cells
○ Spermatids turn into sperm cells and released by sertoli cells into lumen of seminiferous tubules
○ 64 days to finish, end w 4 sperm cells w 23 chromosomes each
○ Sperm cell has head (w acrosome aka tip and nucleus), idpiece w mitochondria, and long tail/ flagellum - from here needs 12 more days to completely mature
- Control of testicular function
○ Function of testes controlled by follice stimulating hormone (FSH) and lutenizing hormone (LH - aka interstitial cell stim hormone) released by anterioir pituitary to gonadotropin releasing hormone (GnRH) from hypothalamus
○ FSh acts on sertoli cells to promote spermatogenesis whil also making hormone inhibin
○ Inhibin feeds ant pituitary to decrease release of LH and FSH
○ LH stims leydig cells to make testosterone
○ Testosterone feeds back to hypothalamus and ant pituitary to dec production and secretion of LH and FSH
- Testosterone
○ Steroid hormone made by leydig cells in testes
○ Production starts w cholesterol and formation of several intermediates ending in production of testosterone
○ Progesterone (female hormone) is one of intermediates leading to testosterone production
○ Is similar in structure to cholesterol and progesterone
- Testosterone lvls and age
○ Rise during fetal development
○ Rise needed for development of male reproductive tracts and external genetalis
○ After birth - small increase - unknown reason
○ Lvls low until puberty then boom up , then slow dec at 40
○ Puberty happ 9-14
○ During puberty, gonadotropin releasing hormone (GnRH) begin to increase - cause unclear, but leads to inc in LH and FSH = causes testosterone lvls to inc
○ This inc causes final maturation of male reproductive system to point where mature sperm is produced
○ Sexual maturity and peak testosterone lvls at 16-18
- Testosterone functions
○ Development of male reproductive tract + external genetalia in embryo
○ Growth and development of all male reproductive organs aat puberty
○ Development of male secondary sex characteristics at puberty (muscle growth, hair growth on face and around genitalia, deep voice)
○ Sex drive at puberty
○ Spermatogenesis
○ Bone and skeletal muscle growth
○ Increased aggressiveness
- Andropause
○ at 50 dec sperm production (called andropause)
○ Andropause may happ bc leydig cells (they make testosterone) may not fully respond to LH
○ Andropause associated w dec sexual desire and erectile function, dec lean body mass, inc obesity, dec bone density
- Female system structure
○ External genetalia collectively called vulva
○ Includes clitoris - small mound of erectile tissue from same embryonic tissue as penis
○ Vulva also has labium majus (labia majora) which surrounds labia minus (labia minora)
○ Labium minora encloses vaginal orifice (opening to vag)
○ Sperm deposited in vag, then goes through cervix to uterus (womb), to fallopian tubes (which ends at fimbria)
○ Egg made in ovaries is released and travels through fimbria to fallopian tubes to meet sperm
- Female system - functions
○ Vagina - birth canal, gets penis and sperm, allows discharge of fluid during period, where baby goes through
○ Cervix - secretes mucus that varies during cycle from thin (facilitate sperm entry) to thick (prevent sperm entry)
○ Uterus - site of implantation of fertilized egg and where developing baby kept, also during period uterine lining goes through several phases
○ Fallopian tubes - site of fertilization of egg, have cilia that pass egg from fimbria to uterus
○ Fimbraie - capture egg after kicked out of varies and funnel it into infundibulum (aka tunnel to fallopian tubes)
○ Ovaries - make eggs (oogenesis) and estrogen and progesterone
