male reproductive system.txt

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male reproductive system.txt
2011-05-12 23:29:44
anat reproductive sys

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  1. gonads
    aka testes: produce sperm & secrete hormones
  2. Ducts in the male reproductive system & role
    • Epididymis: site of sperm maturation
    • ductus deferens
    • ejaculatory ducts
    • urethra
    • AID in transport and storing sperm, assisting their maturation and conveying them to exterior
  3. Accessory glands in male reproductive system & role
    • Seminal vesicles
    • prostate
    • bulbourethral glands
    • AID in adding secretions to semen
  4. Supporting stuctures in male reproductive system
    Scrotum supports testes & penis delivers sperm to female reproductive tract
  5. Scrotal Septum
    • Internally divides scrotum into 2 sacs, each w/single testis
    • Made of subcutaneous layer & dartos muscle
    • Cremaster muscle is associated w/each testis
  6. Sperm production conditions
    • Require 2-3celcius below core body temp to grow
    • Cremaster & dartos muscle contract or relax to help achieve this
  7. Testicles
    • Sperm produced here thru SPERMATOGENESIS
    • Each of 200-300 lobules contain 1-3 seminiferous tubules
  8. Sperm forming cells (in order from beginning to maturation)
    primary spermatocytes -> secondary spermatocytes -> spermatids -> sperm cells -> lumen
  9. Sertoli cells or sustenacular cells
    • Support cells through:
    • nourishing spermatocytes, spermatids & sperm
    • Phagocytizing excess spermatid cytoplasm
    • Controlling movements of spermatogenic cells
    • Releasing sperm into lumen
    • Produce fluid for sperm transport
    • Secrete Inhibin
    • Regulate effects of Testosterone & FSH
  10. Leydig cells location & role
    • found between seminiferous tubules
    • Help secrete Testosterone
  11. Spermatogenesis cycle
    • Takes 65-75 days
    • 1. spermatogonia (2n): Sperm undergo mitosis & some development
    • 2. primary spermatocytes (2n): each duplicates its DNA
    • 3. Meiosis 1 (n): homologous pairs line up, crossing over occurs. 2 haploid cells at end of Meiosis 1..each chromosome has 2 chromatids
    • 4. Meisosis 2 (n): the 2 chromatids seperate into spermatids form (4 haploid cells)
    • cells remain attached by CYTOPLASMIC Bridges
    • 5. Spermiogenesis: spherical spermatids into elongated SPERM. Acrosome and flagella form, mitochondria multiply.
    • Sertoli cells dispose of excess cytoplasm
    • Spermiation: releasing from connections to Sertoli cells
    • sperm not yet able to swim
  12. How many sperm go through spermatogenesis per day
    300mil sperm
  13. How long can sperm survive in female reproductive tract
  14. Sperm Anatomy
    • Head:
    • contains nucleus & 23 chromosomes (haploid - n). Acrosome also here - a vesicle with oocyte penetrating enzymes.
    • Tail:
    • neck contains centrioles forming microtubules comprising remainder of tail
    • Middle piece has mitochondria
    • Principle piece is longest portion
    • End piece is the terminal portion
  15. Hormone Levels and roles to spermatogenesis at puberty
    • secretion of GnRH INCREASES
    • stimulates anterior pituitary to INCREASE secretion of LH and FSH
    • LH stimulates Leydig cells to secrete testosterone...which suppresses further LH & GnRH (via neg feedback)
    • Testosterone is then converted to DHT via Enzyme 5 alpha-reductase
    • FSH and testosterone act on SERTOLI cells to stimulate secretion of androgen-binding protein (ABP)
    • Sertoli cells release INHIBIT, inhibiting FSH
    • Testosterone stimulates spermatogenesis
  16. Androgens (testosterone & DHT) role
    • DHT: stimulates Devel. of EXTERNAL genitalia
    • stimulate devel. of male sex characteristics (organs & 2ndary sex char @ puberty)
    • contribute to male sex BEHAVIOR
    • contribute to Spermatogenesis
    • Contribute to Sex DRIVE (libido)
  17. Epididymis
    • Site of sperm maturation: where it acquires motility & ability to fertilize
    • Sperm storage (for several months)
    • Continues on as ductus (vas) deferens
  18. Ductus (Vas) Deferens
    • Conveys sperm during arousal thru peristaltic contractions
    • Sperm storage (for several months)
  19. Ejaculatory Ducts
    • Union of ducts from seminal vesicle & ampulla of ductus (vas) deferens
    • ends in Prostatic urethra
    • Ejects sperm & seminal vesicle secretions just before release of semen into urethra
  20. Urethra
    • shared terminal duct of reproductive & urinary systems
    • Ends @ urethral orifice
  21. Seminal Vesicles
    • contain 60% of semen volume
    • Secrete alkaline fluid (contains fructose, clotting proteins from blood)
  22. Prostate
    • contains 25% of semen volume
    • Secretes milky, acidic fluid (citric acid, proteolytic enzymes, acid phosphatase & seminalplasmin (antibiotic)
  23. Bulbourethral glands
    • Secretes alklaine fluid that PROTECTS passing sperm by NEUTRALIZING acids from urine (in urethra)
    • Mucus lubricates end of penis & lining of urethra
  24. Erection physiology
    • Parasympathetic fibers release & cause local production of Nitric oxide (NO)
    • NO causes smooth muscle in arterioles to RELAX & dilate, allowing large amounts of BLOOD to enter penis.