Human Reproduction

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Human Reproduction
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Objectives

• To identify the anatomy of the Male Reproductive
  System
• To understand the hormonal controls in sperm
  production
• To identify the anatomy of the Female
  Reproductive System
• To understand the hormonal controls involved in
  the 4 stages of the Menstrual Cycle

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Battle of the sexes!!!
Are males and females all that different? Well..
Yes And No!
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Lets Compare

• Male System simple!
• Female System complicated !!
• Lets look at the Male System first.
• All it does is produce 2-4 million sperm cells
  per day starting at puberty and continuing until
  the day you die!

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Male Anatomy
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Cross-section of the Seminiferous Tubule
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Anatomy of the Seminiferous Tubule

• Spermatagonia 2n reproductive cells that
  undergo meiosis to produce haploid sperm cells
• Interstitial Cells Produce testosterone
• Sertoli Cells provide nourishment for the
  developing sperm cells

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Endocrine System
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Hormonal Control of Sperm Production

• It all starts in your..BRAIN!!
• The Hypothalamus secretes many hormones into your
  blood including GnRH which stimulates the
  Pituitary to secrete 2 hormones called FSH
  Follicle Stimulating Hormone LH
  Lutenizing Hormone
• FSH stimulates sperm production
• LH stimulates testosterone production

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Testosterone

• Promotes more sperm production AND the
  development of secondary sex characteristics
• Negative Feedback
• As levels of testosterone rise the hypothalamus
  detects the levels and
• stops the production of GnRH which
• stops the production of LH which..
• reduces the production of testosterone
• This is called Negative Feedback

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Hormonal Feedback
Hypothalamus
Releasinghormone
Anteriorpituitary
Negative feedback
LH
FSH
Spermproduction
Testosterone production
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Positive feedback

• As dropping testosterone levels are detected, the
  _____________ starts to release ___________,
  which causes the __________gland to release
  ____________, which increases the production of
  ______________.
• This is called Positive Feedback

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Sperm Cells
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Semen

• Semen, not to be confused with seaman, is the
  fluid that sperm cells swim in.
• There are three glands that secrete the fluids
• Prostate gland secretes an alkaline buffer that
  neutralizes the acidic environment of the vagina.
• Seminal vesicles secrete a fructose solution
  that provides energy for the sperm cells
• Cowpers gland secretes a mucous that lines the
  urethra to prevent the sperm from contacting any
  urine residue

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Female Anatomy
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It all starts in the Brain (again)!
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Menstrual Cycle

• 28 day cycle that begins at puberty and continues
  until menopause
• Consists of 4 stages
• Menstruation (your period)
• Follicle Stage
• Ovulation
• Corpus Luteum Stage

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Menstrual Cycle
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1 Menstruation

• 4-6 days
• Endometrium and unfertilized egg are removed from
  the uterus.
• Pituitary gland releases FSH which stimulates the
  follicles in the ovaries.

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Ovary and Follicles
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2 Follicle Stage

• One follicle usually becomes the chosen one and
  continues to enlarge.
• The ovaries release Estrogen
• Rising levels of Estrogen send negative feedback
  to the Pituitary stopping the production of FSH
  and positive feedback initiating the release of
  LH.
• Estrogen causes the endometrium to thicken

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3 Ovulation

• Around day 14, LH levels are at their highest and
  cause the stimulated follicle to rupture and
  release its egg.
• The egg is swept by the fimbria into the oviduct
• You are most vulnerable to becoming pregnant!

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4 Corpus Luteum Stage

• The ruptured follicle changes into a yellowish
  structure called the Corpus Luteum.
• It releases estrogen and progesterone (pregnancy
  hormone)
• If pregnancy results
• Estrogen and progesterone levels stay high,
  preventing the release of FSH by the pituitary
  (NF)

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4 Corpus Luteum Stage

• If pregnancy does not occur
• Estrogen and progesterone levels drop, causing
  the endometrium to deteriorate and menstruation
  begins again.
• Dropping levels of estrogen and progesterone
  cause the pituitary to begin releasing FSH (PF)

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Review of the Menstrual Cycle
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Birth Control Pills

• Trick your body into thinking it is pregnant.
• If your body thinks it is pregnant, you wont
  ovulate.
• Without an egg being released, you cannot become
  pregnant.
• Each pill has different amounts of progesterone.
• The pill can be prescribed to regulate your
  period because of the specific levels of hormones
  found in each pill

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Pregnancy Tests

• Check for the presence of hCG (Human Chorionic
  Gonadotrophin) in the mothers urine
• The fertilized egg releases hCG

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Terms to remember

• Fertilization union of egg and sperm inside the
  oviduct. Fertilization and Implantation
• Implantation attachment of fertilized egg into
  the endometrium 6 to 8 days after fertilization.
• Gastrulation 16 to 18 days after fertilization
• Embryo term used to refer to the developing
  ball of cells after gastrulation up to 8 weeks.
• Fetus after 8-10 weeks

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8 months
4 weeks
5 months
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