The Human Reproductive System

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The Human Reproductive System
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Male Reproductive System
urinary bladder
seminal vesicles
prostate gland
urethra
penis
rectum
epididymis
Cowpers gland
testis/testes
vas deferens
scrotum
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Male Reproductive System (frontal view)
See p. 62 in Review book
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Male Reproductive System

• Scrotum sac of skin that holds testes. Hangs
  below body to keep testes cool. Sperm cannot be
  produced if body is too warm. Testes move into
  scrotum just before birth.
• Testis/testes male gonads. Made up of small,
  coiled tubes seminiferous tubules. 300-600 per
  testis. Immature sperm made here.
• Secrete testosterone

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Male Reproductive System

• Epididymis storage area in upper rear of
  testis. Immature sperm move here to mature
  takes 18 hours.
• Vas deferens tube that leads upwards from each
  testis into lower part of abdomen from
  epididymis.
• Cowpers gland produces fluids that nourish
  sperm and protect them from the acidity of
  female.
• Combination of sperm and fluids - semen

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Male Reproductive System

• 6. Rectum holds wastes
• 7. Seminal vesicles secretes liquid that
  extends sperm life including fructose
• 8. Urinary bladder stores urine
• 9. Prostate gland controls flow of urine
  secretes alkaline solution.
• 10. Urethra passageway for excretion of urine
  and for sperm to leave body. Vas deferens
  empties into urethra

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Male Reproductive System

• 11. Penis male reproductive organ. Facilitates
  internal fertilization
• Ejaculation muscular contractions force semen
  through urethra. Before, during and after
  ejaculation reflex actions keep outlet of bladder
  closed

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Hormones and Negative Feedback in Males

• Negative Feedback change that leads to a
  response that causes something to counteract that
  change
• Luteinizing Hormone (LH) stimulates testes to
  produce testosterone
• Testosterone stimulates development of sperm.
  Once there is a large number of sperm, puberty is
  complete.

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Hormone Negative Feedback System
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• What is the effect of high levels of LH?
• Testosterone is produced
• What is the effect of high levels of
  testosterone?
• Slows production of LH which in turn slows
  production of testosterone
• What is the overall outcome of this on-off
  negative feedback system involving LH and
  testosterone?
• Nearly constant level of both hormones -
  homeostasis

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Male Reproductive System and Hormones

• Explain how LH stimulates the testes to produce
  testosterone.
• Circulates in the blood- reaches the testes
  target cells stimulates them to produce
  testosterone
• What happens when the levels of testosterone are
  too high in the body?
• LH level drops
• What is negative feedback and how does it
  maintain homeostasis?
• Change in conditions triggers response in body
  to counteract that condition. Keeps hormones in
  balance

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Female Reproductive System
oviduct
ovary
Urinary bladder
uterus
urethra
rectum
cervix
vagina
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Female Reproductive System (frontal view)
See p. 61 in Review book
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Female Reproductive System

• Ovary female gonads. Secrete estrogen
  produces secondary characteristics, menstrual
  cycle
• Produces eggs 2 ovaries 4cms long, 2 cms
  wide

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• Follicles each ovary contains 200,000 egg sacs
  called follicles. In each follicle is an
  immature egg.
• All the eggs are present at birth. During the
  womans lifetime 500 eggs mature
• When an egg matures, follicle moves to surface
  of ovary.
• Follicle breaks releases the egg ovulation
• Egg can be fertilized for about 24 hours after
  ovulation

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Female Reproductive System

• 2. Oviduct (fallopian tube) Each ovary is near
  but not connected to oviduct. Tube with
  funnel-like opening. Cilia line it to create a
  current that draws the egg into the tube. Egg is
  fertilized in the oviduct
• 3. Uterus thick, muscular, pear-shaped organ.
  Once egg is fertilized it finishes its
  development in uterus attached to uterine wall

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Female Reproductive System

• 4. Urinary bladder storage of urine
• 5. Urethra passage of urine to outside of body
• 6. Vagina (birth canal) leads to outside of
  body
• 7. Cervix narrow neck of uterus
• 8. Rectum passage for wastes

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The Menstrual Cycle

• What is the menstrual cycle?
• Cycle during which an egg develops and is
  released from the ovary and the uterus is
  prepared to receive a fertilized egg
• Menarche first menstrual period usually occurs
  between 11 and 12
• Menopause time when a woman stops menstruating,
  usually between 45 55 and is no longer able to
  conceive.

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The Menstrual Cycle
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The Menstrual Cycle

• 1. Menstruation Loss of egg and uterine tissue
  via vagina if fertilization does not occur
• 2. Follicle Stage (follicular stage) lasts 10
  days, FSH LH levels increase, egg matures,
  follicle secretes estrogen to prepare uterus

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The Menstrual Cycle

• 3. Ovulation High level of estrogen detected by
  hypothalamus, increased LH, decreased FSH,
  follicle bursts egg released
• 4. Corpus Luteum Stage (Luteal Phase) LH
  converts follicle to corpus luteum secretes
  estrogen progesterone. Progesterone prepares
  uterus. Increased progesterone keeps LH FSH
  low

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Hormones of Menstrual Cycle

• What happens if fertilization occurs?
• Corpus luteum keeps producing progesterone to
  maintain pregnancy. After 5 weeks the embryo
  produces progesterone this inhibits LH FSH so
  no menstrual cycle
• What happens if fertilization does not occur?
• There is no implantation the corpus luteum
  breaks down. Progesterone level drops, uterine
  lining breaks down menstruation.
• FSH LH are produced again new cycle
• Average Menstrual Cycle is 28 days long

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Ovulation to Implantation
oviduct
uterus
egg from ruptured follicle
ovary
cervix
follicle
vagina
sperm
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Ovulation to Implantation

• Ovary produces estrogen progesterone
  meiosis occurs egg develops
• Egg matures in follicle of ovary
• Ovulation egg released from follicle may live
  for 24 hours
• - egg moves into fallopian tube by cilia

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Ovulation to Implantation

• Events in fallopian tube
• Fertilization occurs here. Sperm lives 4-5 days
  (egg lives 1 day)
• Zygote undergoes mitosis travels down fallopian
  tube within 6-10 days. Zygote is ready to
  implant into uterus.

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End of Presentation