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Reproductive System. Honors Anatomy & Physiology. Male Anatomy. Structures & Their functions. External Genetialia : Penis – copulatory organ Shaft, glans (enlarged tip), prepuce (foreskin) Erectile (spongy) tissue – connective tissue, smooth muscle, and vascular spaces
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Reproductive System Honors Anatomy & Physiology
Structures & Their functions • External Genetialia: • Penis – copulatory organ • Shaft, glans (enlarged tip), prepuce (foreskin) • Erectile (spongy) tissue – connective tissue, smooth muscle, and vascular spaces • Erection – sexual arousal triggers parasympathetic release of NO causing arterioles to dilate, engorgement restricts drainage • Testes (gonads)-1.5” x 1” sperm & testosterone production • Scrotum – maintain testes temp 3oC lower than body temp (retractable) • Duct System (sympathetic control over ejaculation) • Epididymis –20 ft long, 20 days for sperm to become motile, may be stored for months (ejaculated by smooth muscle or phagocytized) • Ductus deferens – 18” long, thick smooth muscle • Ejaculatory duct – through the prostate and empties into urethra • Urethra – both urine & sperm (has priority!) • 3 regions: prostatic urethra, membranous, spongy
Semen • Semen – milky white, sticky secretion of sperm & secretions • 2-5mL per ejaculation • 20-150milliom sperm per mL • Catabolism of fructose provides ATP for flagella • Prostaglandins stimulate uterine peristalsis • Accessory Glands • Seminal vesicles – 60% of semen: yellow, viscous alkaline fluid w/fructose, ascorbic acid, prostaglandins enhancing sperm motility • Prostate Gland – 30% of semen: milky acidic fluid w/enzymes to activate sperm • Bulbourthral glands – pea sized glands secrete a thick clear mucus to neutralize acidic urine in urethra “pre-ejaculate”
Structure of the testis • Surrounded by 2 membranes: • Tunica vaginalis • Tunica albuginea • Divided into 250-300 lobules • Ea/w 1-4 seminiferous tubules (sperm production) • Surrounded by myoid cells – contract to squeeze sperm out of testis into rete testis
Spermatogenesis • Begins @ age 14 • Makes ~400million sperm/day • Spermatogonia – divide by mitosis • @puberty some become primary spermatocytes generating secondary spermatocytes • Producing non motile spermatotids
Female External Genitalia • Vagina – 3-4” birth canal & copulation organ • 3 layers: outer fibroelastic, smooth muscle, ridged mucosa • Acidic pH – antimicrobial but hostile to sperm • Hymen – vascular membrane in virgins • Mons pubis – fatty ridge • Labia: majora & minora– enclose the vestibule or entrance • Vestibular glands – secrete mucus • Clitoris – innervated erectile tissue hooded by prepuce
Ovaries • Produce Ova (eggs) & Sex hormones • Ovarian ligament anchor to uterus & suspensory ligament to pelvic wall • Ovarian follicles ea/contains oocytesurrounded by follicle cells • Primordial follicle – 1 layer cells surround oocyte • Primary follicle – 2 + layers of cells • Secondary follicle – fluid filled cavity appears • Graafian follicle – follicle bulges from ovary surface, mature oocyte • Ovulation – oocyte ejected from ovary • Corpus luteum– follicle degenerates into scars/pits
Oogenesis • Fetal period – oogonia divide by mitosis • (7 million) Primary oocytesin primary follicles begin meiosis I, and stall in prophase I (2 milion) • Puberty 250,000 oocytes remain • 1 selected every 28 days to complete meiosis I, first polar body undergoes apoptosis, secondary oocyteis suspended in metaphase II when ovulated • <500 released over 40 years • After fertilized, it completes meiosis II, creating a second polar body that deteriorates and 1 large ovum
21-40 days, avg 28 days) Ovarian Cycle • @puberty pituitary releases FSH & LH stimulating ovaries • Follicular Phase (days 1-14) • Menstration(days 1-5 ) • endometrium sheds • Low estrogen & progesterone • Proliferative Phase (day 6-14) • FSH & LH • follicle growth • estrogen (- feedback on release FSH & LH, + feedback on estrogen) • Endometrial lining thickens • Cervical mucus thins • Ovulation (day 14) • estrogen causes surge of LH & FSH, then drops • Ovary expels 2ooocyte w/corona radiata • Mittlschmerz– abdominal pain due to ovarian wall stretching • Luteal /Secretory Phase (days 14-28) • estrogen • progesterone (thickens endometrium) • Corpus luteum degenerates
Female Duct System • Uterine (fallopian) tubes • Receive ovulated oocyte • About 4” long • Fimbraie – ciliated finger like projections on distal end create current to capture oocytes • Infundibulum – funnel shaped structure • Smooth muscle (peristalysis) & mucosa ciliated lining • Uterous (womb)- nourish fertilized ovum • Inverted pear in size and shape • 3 regions: fundus, body, & cervix • 3 layers of wall: • Perimetrium– outermost layer • Myometrium – smooth muscle • Endometrium – 2 layers of mucosal lining (inner layer sheds)
Menopause • 20’s reproductive peak • 30’s ovarian function (quality of oocytes) declines, still ~100,000 oocytes left • By 50, only ~3 oocytes left • Estrogen production declines • Menstrual periods erratic & shorter, until ovulation & menstruation ceases • Menopause reached after 1 year w/o menstruation
Mammary Glands • Produce milk by modified sweat glands • Areola – ring of pigmented skin surrounding nipple • Ea gland/ 15-25 lobes consisting of lobules containing alveoli that produce milk • Milk passes into lactiferous ducts which open at nipple