Sexual Reproduction
Male Reproductive System
Gonads Testis: Seminiferous tubules: coiled ducts (~ long), where (male sex cell) made (several 100 million/day) Intestitial cells (Leydig cells): between tubules & secrete Scrotum: sac that holds testis outside , which provides lower temperature ( °C) needed for sperm production
Duct System Epididymis: coiled tubes in sac (~6m long), where sperm mature over days & stored for weeks Ductus deferens (Vas Deferens): tube that sperm from testes to by peristalsis during ejaculation curves around & empties into urethra
Accessory Organs Seminal Vesicles: produces thick, secretion into vas deferens that: has pH (basic): protects sperm from low pH (acidic) in vagina contains : provides energy for sperm contains : causes uterine contractions, which sperm towards egg located at of urinary bladder
produces thin, white secretion into deferens that: Prostate Gland: produces thin, white secretion into deferens that: has alkaline pH to: neutralize pH in vagina increases pH to activate sperm ( at pH 7.5) helps sperm located below urinary bladder & top of urethra
Cowper’s gland (bulbourethral gland) produces secretion into urethra that: has alkaline to protect sperm from urine (acidic) in urethra provides during sexual intercourse pea–sized located below prostate NOTE: sperm become motile (capable of ) after maturing in epididymis, but not active exposed to secretions from seminal vesicles & prostate gland in vas
Penis external structure that delivers sperm into erectile tissue: sponge–like with many that fill with blood by constricting veins during glans penis: head that contains many endings for sexual excitement force of ejaculation provided by of smooth muscle in vas deferens, then skeletal in pelvis
SPERM: head: contains acrosome: enzymes to help sperm penetrate egg midpiece: contains mitochondria to provide energy for tail tail: flagellum for movement continuously made in seminiferous of testes through
Spermogensis spermatogonia (46 chromosomes) → meiosis & differentiation → sperm cell (23 chromosomes)
Route of Sperm during , 200–500 million sperm ejaculated in 3–4mL of seminal sphincter at of bladder before ejaculation
SEMINAL FLUID (SEMEN) fluid expelled from penis that secretions from , seminal vesicles, prostate gland, & Cowper’s gland sperm in fluid survive only 24–48 h Functions provides medium for of sperm provides for sperm activates sperm by alkaline pH neutralizes urine in urethra neutralizes acidic environment of vagina provides which cause uterus to contract (sperm to egg) provides lubrication intercourse
Testosterone: male sex hormone produced by testes in males & adrenal medulla in females (in lower conc.) Functions in males: before puberty, development of penis & testes (sex organs) at puberty, stimulates: spermatogenesis sex drive development of male sex characteristics, facial, , & pubic hair products from oil & sweat glands in skin, which causes acne enlargement of larynx, which causes voice increased strength aggression baldness (if gene present) Function in females: body (muscle & bone), sex drive, & pubic hair growth
leutenizing hormone (LH): stimulates secretion of follicle hormone (FSH): stimulates spermatogenesis NOTE: testosterone also required for spermatogenesis secretion from pituitary gland stimulated by secretion of gonadotropin hormone (GnRH) from hypothalamus secretions from hypothalamus & anterior gland regulated by testosterone in blood plasma through negative NOTE: LH, FSH, & testosterone secreted into blood plasma
By the End of this Section You should be able to : identify and give functions for each of the following: – testes (seminiferous tubules and interstitial cells) – scrotum – epididymis – ductus (vas) deferens – prostate gland – Cowper’s glands – seminal vesicles – penis – urethra describe the path of sperm from the seminiferous tubules to the urethral opening List the components seminal fluid (as contributed by the Cowper’s glands, prostate gland, and seminal vesicles), and describe the functions of each component identify the tail (flagellum), midpiece, head, and acrosome of a mature sperm and state their functions describe the functions of testosterone describe the homeostatic regulation of testosterone levels by the hypothalamus, anterior pituitary, and testes