The Reproductive System

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The Reproductive System
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Function of the RS

• Produce, store, nourish and transport male and
  female gametes
• Gametes (ovum and sperm) are produced by meiosis
  (specialized cell division)
• The joining of gametes is called fertilization
  and produces a zygote.

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Meiosis

• Process which produces cells with half the normal
  number of chromosomes.
• Spermatogenesis
• oogenesis

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Keeping chromosome number stable

• All cells in body have 46 chromosomes
• Meiosis keeps chromosome number the same from
  generation to generation but allows for variation

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Basic structural overview

• Gonads (reproductive organs)
• Ducts (for transport)
• Accessory glands/organs which produce secretions
• External genitalia

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Structures of the Male RS

• Testes
• Vas deferens (ductus deferens)
• Seminal vesicle
• Ejaculatory duct
• Prostate gland
• Urethra
• Bulbourethral gland
• Penis

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Testes

• Primary sex organ of male
• Housed in scrotum
• Sperm is produced in seminiferous tubules and
  stored in epididymis
• Sex hormones also produced here

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Sperm

• Specialized cell which contains
• nucleus (DNA)
• lysosomal enzymes (acrosome)
• mitochondria (to power the flagella)
• flagella (to move the sperm)

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Vas deferens

• Also called ductus deferens
• Is what is cut in a vasectomy
• transports sperm from epididymus
• becomes ejaculatory duct after it connects with
  seminal vesicle

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Seminal vesicle

• Accessory gland which contributes
• 60 of the volume of semen
• Secretions
• high in fructose
• slightly alkaline

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Ejaculatory duct

• Transports semen from where DD meets seminal
  vesicles until it becomes urethra

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Prostate gland

• Accessory gland located below urinary bladder
  that surround beginning of urethra
• Produces 30 volume of semen
• Secretions are acidic

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Bulbourethral gland

• Accessory gland
• also called Cowpers gland
• Secretions which aid in lubrication are
• alkaline
• thick, sticky
• mucilaginous

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Urethra

• Transports urine and semen to outside of body
• Runs through penis

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Penis

• Tubular organ which surrounds urethra and permits
  deposition of semen internally
• Structures include
• body (shaft)
• glans (head)
• corpora cavernosa (erectile tissue)
• corpus spongiosum (erectile tissue)

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Structures of the Female RS

• Ovaries
• Oviduct (uterine tubes, Fallopian tubes)
• Uterus
• Cervix
• Vagina

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Ovary

• Where oogenesis occurs, producing ova
• Also secretes female sex hormones (estrogens and
  progestins)

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Ovarian Cycle

• Follicle is where ovum is produced
• Occurs once per month
• Ovulation is when follicle releases ovum
• After ovulation follicle becomes corpus luteum
• CL produces hormones

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Oviduct

• Collects and transports ovum to uterus
• Site of fertilization
• cutting tubes can be used as sterilization
  procedure (tubal ligation)

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Uterus

• Several layers
• Endometrium (secretory layer)
• Myometrium (muscle layer)

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Uterine Cycle

• Also known as menstrual cycle
• Repeated changes in endometrium
• 3 phases
• Menstruation
• Proliferative phase
• Secretory phase

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Cervix

• Opening of uterus from vagina
• Changes diameter to allow passage of fetus

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Vagina

• Muscular tubes extending between uterus (cervix)
  and outside of body
• Contains Greater vestibular glands which secrete
  lubrication into vestibule
• Several Functions
• Passageway for elimination of menstrual fluids
• Reception of penis during intercourse
• Birth canal

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External Genitalia

• Vulva region enclosing external genitialia
• Vestibule central space where vagina and
  urethra open into
• Labia minora 2 folds of skin which protect
  vestibule
• Clitoris erectile tissue at anterior of
  vestibule
• Labia Majora 2 folds of skin which protect
  labia minora
• Mons Pubis bulge anterior to Labia Majora
  created by fat tissue beneath the skin.

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Mammary Glands

• Specialized accessory organs
• Site of milk production (lactation) following
  birth of infant
• Nipples are where ducts from glands open onto
  skin