Reproductive System

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Reproductive System

• Chapter 21

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Introductory objectives

• 51. Explain how chromosomes determine the sex of
  a newborn child.
• 52. Explain how the gene of sexuality expression
  varies among individuals.
• 53. Describe some aspects of sexual behavior that
  are strongly influenced by culture and others
  that may be heredity.
• 54. Define and give examples for primary and
  secondary sex characteristics (lecture only not
  in text).

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Assorted Objectives

• Obj. 51 previously covered.
• Obj. 52 gene of sexuality expression lots of
  ideas about this, but no proven facts.
• Obj. 53 sexual behaviors influenced by culture
  many
• - sexual behavior influenced by heredity much
  harder to prove. ssee section 21.1

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Primary Secondary Sex Characteristics Obj. 54

• Primary ones related directly to reproduction
  specifically
• testes penis in males,
• Ovaries, uterus, vagina in females.
• Secondary ones related to maleness or
  femaleness, but not DIRECTLY to reproduction.
• - hairiness, deeper voice, stronger muscles in
  males.
• Breasts (or feeding young, but not for producing
  them), wider hips (for childbearing), higher
  voice, etc.

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Behavioural Characteristics 55

• See How Science Works, section 21.1
• - since breasts and buttocks are areas of fat
  storage, perhaps men look for women who are
  nutritionally healthy, due to their large b and
  b.
• - in other words, not too much hard scientific
  fact on these topics.

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Objective 56Male reproductive system

• Parts
• Penis
• scrotum
• Testis (testes)
• Epididymis
• Vas deferens
• Urethra
• Prostate gland
• Seminal vesicles

• Functions
• Urination and sperm ejaculation.
• Holds testes, moderates temperature.
• Sperm production, maturation, hormone production.
  
• Sperm maturation within testis.
• Transfer of sperm to urethra
• Transport of urine and semen
• Both add fluids, lubrication and nutrients to
  sperm to form semen.

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Objective 56Male Reproductive System
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Objective 56Female Reproductive System

• Parts
• Ovaries -
• Oviducts -
• Uterus
• Vagina
• Clitoris -
• Labia -

• Functions
• produce eggs and hormones
• Lead eggs from ovaries to uterus
• Prepares for and contains pregnancy
• Canal for intercourse and birth canal.
• Vascular, female equivalent of penis.
• Flexible, protective lips.

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Objective 56Female Reproductive System
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Objectives 59Hormonal Interactions

• Master gland is the pituitary, which in turn is
  controlled by the hypothalamus.
• Pituitary sends messages (gonadotropins) to
  gonads (testes or ovaries)
• Male Testes produce androgens such as
  testosterone (adrenal glands also produce
  androgens). Also others.
• Female more complicated see next.

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Objectives 59Female hormonal interactions

• Pituitary sends gonadotropins to ovaries
  specifically FSH and LH.
• Ovaries, on 28-day cycle, produce estrogens
  (general female features) and progesterone.
• Progesterone, in combination with estrogen,
  affects uterine cycle.
• If pregnancy occurs, embryonic tissue produces
  human chorionic gonadotropin.

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Objective 60Ovarian Cycle - 1

• 28 day cycle, but varies
• day 1, FSH from pituitary stimulates growth of
  ovarian follicle, which secretes estrogen
• Estrogen secretion peaks day 14, and causes
  ovulation.
• Follicle becomes corpus luteum, which secretes
  estrogen and progesterone, which promote
  thickening of uterine lining.
• E and P reach peak third week, resulting in
  maximum readiness of uterine lining.
• E and P then decline, resulting in breakdown of
  uterine lining ? menstruation toward end of cycle.

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Objective 60 Ovarian Cycle - 2
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Objective 60 Uterine Cycle - repeat

• Toward end of 28 day cycle, uterine lining
  breaking down.
• Day 1 is considered to be the first day of the
  menstrual cycle.
• Days 1-4 menstruation or menstrual period.
• days 5-20 gradual buildup of endometrium in
  response to progesterone.
• day 19 implantation of fertilized ovum (or
  not).
• If no implantation, uterine lining breaks down in
  last few days of the cycle, then starts again.
• If implantation occurs, see slide after next.

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Objective 60 Ovarian and Uterine Cycles
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Objective 60 If Implantation Occurs

• Fertilized egg implants about five days after
  ovulation - day 19 or 20.
• Fertilized egg divides to form embryo, and also
  assorted other tissues including placenta.
• Placental tissues secrete human chorionic
  gonadotropin, which sends signals to maintain
  estrogen and progesterone secretion to maintain
  uterine lining until placenta can start to
  produce its own E and P.
• Etc. covered in a different course.

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Objective 60 Feedbacks

• There are feedback mechanisms at all stages, e.
  g.,
• buildup of FSH and LH sends a negative feedback
  signal to hypothalamus.
• buildup of estrogen and progesterone does the
  same for ovaries.
• HCG feeds back to maintain estrogen and
  progesterone a type of positive feedback.

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THE END

• Of the section on reproduction
• Of the new material for the coursesigh!!
• and the beginning of the review
• more sighs .