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Human Reproductive System

Human Reproductive System. Produces, stores, nourishes and transports functional gametes (egg and sperm). Fertilization - union of sperm and egg = zygote. Structures. Gonads – make gametes! Ducts – gametes and fluid travel through. Accessory Organs and Glands External Genitalia.

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Human Reproductive System

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  1. Human Reproductive System Produces, stores, nourishes and transports functional gametes (egg and sperm). Fertilization - union of sperm and egg = zygote. Structures • Gonads – make gametes! • Ducts – gametes and fluid travel through. • Accessory Organs and Glands • External Genitalia

  2. Male Gonads • Testes produce sperm and testosterone. • Female Gonads • Ovaries produces eggs, estrogen and progesterone.

  3. Male Reproductive Structures

  4. Male Reproductive Structures 1o Reproductive organ: Testes • Scrotum - encloses testes. • Dartos muscle wrinkles skin of scrotum. • Cremaster muscle pulls testes closer to body.

  5. Structure of the Testes Figure 27.4a

  6. Seminiferous Tubules • Site of sperm production - contain spermatogonia (stem cells) • Efferent ducts connect rete testis to epididymis. • Interstitial cells - secretes testosterone.

  7. Epididymis – about 18 feet long (3 weeks). - Head - Body - Tail Stores spermatozoa (recycles damaged spermatozoa) Maturation of Sperm cells Ductus deferens – starts after tail of epididymis

  8. Ductus Deferens • Muscular tube that transports and stores spermatozoa - begins at epididymis. • Connected to abdominal cavity via spermatic cord. • Passes through inguinal canal. • Fuses into ejaculatory duct (see figure). • Empties into urethra.

  9. Accessory Organs of the Male • Seminal vesicles All of these structures secrete semen into ejaculatory ducts and urethra • Prostate gland • Bulbourethral glands Seminal Vesicles • Paired glands - secretes 60% semen volume. • Fibrinogen – converts to fibrin. • Fructose – a sugar for energy! • Prostaglandins – contract female tract.

  10. Prostate Gland • Single gland - secretes 30% semen volume. • Clotting enzymes – to cause initial clots. • Fibrolysin – to liquefy clots. Bulbourethral Glands • Paired glands (~5% semen volume). • Alkaline mucus secretion (to neutralize). • Lubricating properties.

  11. The Accessory Glands

  12. Semen • Typical ejaculation releases 2-5 ml. • Sperm count typically 50 – 100 million per ml. • Sperm count below 20 million per ml, considered “infertile”. • Sperm must be 2-3o F cooler than rest of body, hence kept ‘outside’ in scrotum.

  13. The Spermatic Cord Connective tissue, fascia and muscle. Encloses these structures: ductus deferens, testicular artery, testicular vein, cremaster muscle. Pampiniform plexus, lymphatics and nerves. All these travel through inguinal canal.

  14. Male Urethra • Urinary bladder to tip of penis • Three regions • Prostatic urethra • Membranous urethra • Penile urethra • Lined with transitional epithelium.

  15. The Penis • Root, body (shaft) and glans. • Prepuce (foreskin) surrounds tip. • Erectile tissue (3 masses) • Two corpora cavernosa • One corpus spongiosum(surrounds urethra) • Erection – dilation of arterial smooth muscles.

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