Name Block Date Bio 12 Notes: Reproductive System Intro & Male System I) Intro -many organisms reproduce asexually (1 parent only): binary fission, parthenogenesis -advantages: -disadvantage: -sexual reproduction happens in most organisms (multicellular ones) -advantages - : sexual cell with ½ the # of chromosomes which combine with gamete of opposite gender during - : male gamete, usually small and motile - : female gamete, usually large and non-motile with large nutrient store to support embryonic development, often called an egg cell II) Male Reproductive System (more parts, simpler hormones) A) Main Structures 1) (plural = testes): -develop in abdomen, descent 2 months-few days before birth into the scrotum through the inguinal canal. Cannot retreat: membrane grows and blocks canal (scrotal sac) holds testes outside body where _ 37 degrees Celsius = too hot. Ideal temp to keep sperm alive: 32-35 degrees -testes mostly a “tangle” of -seminiferous tubules are lined with undifferentiated - in tubules assist sperm maturation by providing nutrients and phagocytizing excess cytoplasm from meiotic/mitotic events -testes also composed of 2) : receives sperm from seminiferous tubules via small tubes called _ - cells up to several weeks -sperm undergo further maturation here, leave during ejaculation 3) ________________________: transport sperm (from each epididymis) up to 4) ejaculatory duct: location where and where 3 accessory glands secrete (swimming medium for sperm cells) -semen = ____________________ & _________________________ -during ejaculation ~3.5 mL semen is released with 400-500 million sperm cells 5) Accessory glands a) (2): secrete fluid into ejaculatory duct that contains 1) : source to produce ATP for swimming sperm 2) : hormones that cause that aid through female. (sperm arrive at oviducts in ~ 5 minutes with help of prostaglandins) b) (1): secretes a (~pH 7.5) into ejaculatory duct -vagina is acidic which kills bacteria, but also sperm cells -recall: prostate positioned at base of bladder with urethra running through it. Trouble with urination in male is often a sign of enlarged prostate, a precursor to prostate cancer c) (2) (aka bulbourethral glands): secretes which aids passage of sperm and protects sperm from (from passage of urine) 6) : conducts semen from -recall: also transports urine from bladder -passes through (organ of copulation) that is inserted into vagina during -allows efficient transfer of sperm: deposited at cervix (base of the uterus) which is much closer to “target” -contains which fills with blood during sexual arousal causing erection: blood enters erectile tissue and fills normally empty sinuses. Penis expands in length and girth. Average erect penile length: 13-15 cm (average flaccid length: 9-10 cm) -erectile tissue allows B) Spermatogenesis: creating sperm cells -produced from puberty until late in life (world’s oldest father = 94) -__________________________________: stem cells inside seminiferous tubules -in adolescence, these respond to an increase in testosterone (secreted by interstitial cells) and differentiate into 1 spermatocytes -undergo meiosis 1 to form 2 spermatocytes -undergo meiosis II to form ___________________ (________________________) -spermatids differentiate and mature into sperm cells with 3 main parts 1) _____________: nucleus & a limited amount of cytoplasm, and the ____________________ (contains enzymes that digest egg outer coating and allow penetration) 2) _________________: full of mitochondria to produce ATP for swimming 3) _______________: made of a single Sketch OVER Self Quiz: Can you identify each structure?