Human Anatomy

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Human Anatomy

• Male Reproductive System

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Functions of ?and ?

• Production of sex cells (1 sex organ)
• Delivery of sex cells to place of fertilization
• ? -- development of embryo/fetus

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Overview of Male
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Testes (Testis, sng.)

• 1 sex organ
• production of sperm
• Secretion of testosterone
• Suspended within the scrotum
• Scrotum is a pouch of skin with a thin muscular
  wall
• Testes first appear at 7 weeks next to kidneys

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Cryptorchidism

• Failure of one or both testes to descend into the
  scrotum prior to birth
• 3 of full term males
• 30 of premature males
• Most descend w/in a few weeks after birth
• Sterility occurs if not descended
• Usually removed by puberty -- cancerous

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Testes
scrotal sacs separated
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Scrotum

• Wall comprised of smooth muscle the Dartos
• Cremaster m. (skeletal m.) attached to dermis
• Temperature control of testes
• Sperm development occurs at 35
• Sperm will not develop at body temperature.

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Testes
Comprised of hollow tubing seminiferous tubules
This is where sperm develop
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Seminiferous Tubules
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Seminiferous Tubules
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Seminiferous Tubules

• Each testis contains 800 seminiferous tubules.
• Each tubule is about 2.5 ft. in length.
• Each testis contains one half mile of tubing.
• Sperm maturation takes about 9 weeks.

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Sperm
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Structure of Sperm

• Sperm cells consist of
• Head containing the nucleus (male DNA)
• Middle piece and neck contains large spiral
  mitochondrion
• Tail corkscrew motion to propel sperm
• Acrosome membrane bound bag of enzymes covering
  head.

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Structure of Sperm
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Testosterone Production
Occurs in cells between seminiferous tubule.
Interstitial cells
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Epididymis
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Epididymis

• Located on posterior/superior border of testes
• Acts as recycling center for damaged sperm
• Stores sperm for up to 2 months
• Allows sperm to be fully functional --
  capacitation

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Ductus (vas) Deferens
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Ductus (vas) Deferens

• About 16 in. long
• Begins at end of epididymis
• Ascends into the abdominal cavity by piercing the
  anterior muscles
• Courses around posterior surface of bladder
• And then into the prostate gland

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Ductus (vas) Deferens
Vas wall is mostly smooth muscle contraction
propels sperm to utethra
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Ejaculatory Duct
Ejaculatory duct enters prostate gland
Starts where vas fuses with 1st gland seminal
vesicle
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Three Glands

• Secretions that mix with sperm.
• Sperm secretions semen (ejaculate)
• Typical ejaculate is about 2 5 ml (about 1
  teaspoon containing 500 million sperm)
• 3 glands are
• Seminal vesicles
• Prostate gland
• Bulbourethral glands

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1. Seminal Vesicles
Posterior surface of urinary bladder
Contains large amount of fructose
60 of total semen volume
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Prostate and Urethra
Ejaculatory duct enters urethra
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2. Prostate Gland
Read Clinical Brief p. 735
Contributes to 25 of semen volume
May help prevent infections
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3 Portions of the Urethra

• Prostatic within the prostate gland
• Membranous passes through the pelvic muscles to
  enter the penis (shortest)
• Penile courses the entire span of the penile
  shaft (longest)

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3 Portions of the Urethra
1
3
2
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3. Bulbourethral Glands
Secretes into membranous urethra alkaline mucous
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Penis
glans
body (shaft)
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Body (shaft)

• Consists of 3 parallel columns of erectile tissue
• 2 corpora cavernosa
• 1 corpos spongiosum
• Urethra runs through corpus spongiosum