Reproductive system

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Reproductive system

• Part I Intro and The hormonal control

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Do you need an introduction?

• Connected series of organs and glands that are
  designed to produce and nurture sex cells and
  then transport them to the site of fertilization.
• Sex cells carry 23 chromosomes ( ½ a full
  complement)
• Male cells sperm
• Female oocytes (egg cells)
• Glands and organs secrete hormones and chemicals

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It is a hormonal thing

• The development of the sexual characteristics is
  a hormonal thing
• The human body defaults to the female state if
  there is no testosterone available.
• This is why you can't tell gender until the third
  month. The testosterone hasn't produced enough to
  change the external genitalia.

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Male hormonal

• Hypothalamus produces gonadotropin-releasing
  hormone (GnRH)
• Goes to the anterior pituitary gland
• Anterior pituitary gland -produces luteinizing
  hormone (LH) (AKA interstitial cell stimulating
  hormone- ICSH) and follicale-stimulating hormone
  -FSH
• ICSH targets testicular interstitial cells and
  the adrenal cortex
• makes testosterone
• FSH seminiferous tubules supporting cells to
  respond to testosterone to make sperm

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Male sex hormones AKA Androgens

• Testicular interstitial cells make most
• Testosterone is most abundant
• Attaches to plasma proteins and is transported in
  the blood
• Secreted in fetal development until a few weeks
  after birth, and then is stopped until about
  12-13 yrs old. It continues for the rest of the
  life
• Some males stop producing enough testosterone in
  the middle years
• Natural reduces during and after male climacteric
  (a decline in sexual functions associated with
  age)

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What testosterone does for males...

• Enlargement of testes and accessory organs
• Development of secondary characteristics
• Increase growth of body hair, can slow hair
  growth on scalp
• Enlarges larynx and thickens vocal cords
• Thickening of skin
• Increase muscular growth, broadening of
  shoulders, narrowing of waist
• Thickening and strengthening of bones

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A few more points

• Testosterone
• Increase cellular metabolism and red blood cell
  production
• Stimulates sexual activity by affecting portions
  of the brain
• The greater the amount of testosterone will
  determine the amount of development of the
  secondary characteristics
• Is part of a negative feed back loop

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A minor but important player

• Estrogen
• New studies are linking it to sex drive and
  fertility
• Is typically made by converting testosterone
• Linked to bone mass retention
• Studies are just now beginning to study this
  hormone in depth in males.

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On the ladies side

• Once again GnRH goes to work on the anterior
  pituitary gland
• LH and FSH is made in the anterior pituitary
  gland and goes to the ovaries to support the
  development of eggs and the production of female
  sex hormones. The adrenal cortex is also
  stimulated to make sex hormones
• Placenta secretes hormones during pregnancy

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Primary hormone 1

• Estrogen is the most abundant made in ovaries (in
  non pregnant females)
• Responsible for the secondary sex
  characteristics
• Development of breast and ductile system of the
  mammary glands
• Increase deposition of adipose tissue in the
  subcutaneous layer generally and in the breast,
  thighs, and buttocks in particularly
• Increase blood vessels in the skin
• Enlargement of accessory organs
• Vagina, uterus, ovaries, and uterine tubes

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Primary hormone 2

• Progesterone made primarily in the ovaries
  (except in pregnant females)
• Responsible for the changes in the uterus during
  the females cycle
• Affects the mammory glands
• Helps to regulate the secretion of LH and FSH

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Not primary, but still important

• Androgen (the male sex hormone)
• Produced in the adrenal cortex
• Responsible for increased hair growth in pubic
  areas and axillary regions
• Lower amounts allow for narrow shoulders and
  broad hips
• Linked to sexual desire