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Human Reproductive System

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Title: Human Reproductive System


1
Human Reproductive System
2
Gametogenesis
  • Occurs in the gonads (ovaries and testes)
  • Meiosis that results in the production of gametes
    (haploid) from germ cells (diploid cells)
  • Spermatogenesis and Oogenesis

Slide 2 of 18
3
Oogenesis
  • Occurs in the ovariesresults in the production
    of 1 egg (and 3 polar bodies)
  • Begins when the female is an embryoall primary
    oocytes form before birth and remain frozen in
    this stage indefinitely

Slide 3 of 18
4
Oogenesis
  • Each month after puberty, one primary oocyte
    completes Meiosis I and begins Meiosis II
  • Meiosis II is completed only after fertilization
    occurs.

Slide 4 of 18
5
Oogenesis
  • Characterized by unequal division of cytoplasm.
  • Why does it make sense for this to happen?
  • Allows for more nutrients to be available to the
    egg in case fertilization occurs.

Slide 5 of 18
6
Spermatogenesis
  • Occurs in the testes in the seminiferous
    tubulesresults in the production of 4 sperm
  • Mature in the epididymis and gain motility
  • Produced constantly after puberty

Slide 6 of 18
7
Spermatogenesis
  • The midpiece contains lots of mitochondriawhy?
  • The sperm have a long journey ? they need a lot
    of energy (hence the need for lots of
    mitochondria)

Slide 7 of 18
8
Male Reproductive System
  • Testes where spermatogenesis takes place
  • Epididymis where sperm mature
  • When sperm leaves the body, it will go up the vas
    deferens, past the following glands
  • Bulbourethral gland
  • Prostate gland
  • Seminal vesicles

Slide 8 of 18
9
Male Reproductive System
  • Secretions of these 3 glands, contribute to the
    semen
  • Bulbourethral glands - produce an alkaline
    solution to neutralize acidity of urethra
  • Prostate gland clotting enzyme to make semen
    gelatinous, solution to make environment in
    uterus more friendly
  • Seminal vesicles solution that contains food
    (fructose) for the sperm.

Slide 9 of 18
10
Pathway of Semen
  • Epididymis ? Vas Deferens ? Urethra
  • A vasectomy is a procedure in which the vas
    deferens is cut so that the man will no longer be
    able to father children.

Slide 10 of 18
11
Female Reproductive System
  • Ovaries where oogenesis takes place
  • Oviduct (Fallopian Tube) where fertilization
    takes place
  • Uterus where the embryo grows and develops
  • Vagina birth canal

Slide 12 of 18
12
Female Reproductive Hormones
  • See hormone chart in notes
  • GnRH released from hypothalamus causes the
    release of LH and FSH from the pituitary gland
  • LH and FSH act on the ovaries and cause them to
    produce estrogen and progesterone
  • Feedback mechanisms will be discussed in the next
    few slides

Slide 13 of 18
Image taken without permission from
http//bcs.whfreeman.com/thelifewire/
13
Female Menstrual Cycle
  • Each month, a womans body prepares for the
    possible fertilization of an egg
  • Ovarian Cycle an egg matures (from a primary
    oocyte) and is released
  • Uterine Cycle the endometrium (lining) of the
    uterus builds up (becomes ready to have a
    fertilized egg implant) then breaks down (if no
    fertilization occurs).

Slide 14 of 18
14
Female Menstrual Cycle
  • An oocyte the cells around it follicle
  • Usually, only one follicle fully matures during
    each ovarian cycle
  • Ovulation release of egg from ovary triggered
    by a surge of LH.

Slide 15 of 18
15
Female Menstrual Cycle
  • The corpus luteum is the remaining cells of the
    follicle
  • Continues to produce estrogen and progesterone
    for approximately 2 weeks ? maintains the
    thickness of the endometrium
  • If no fertilization occurs, it degenerates ?
    endometrium is no longer maintained.
  • This starts the whole cycle over again.

Slide 16 of 18
16
Female Menstrual Cycle
  • Day 1 first day of a womans period
  • Hormonal control is complicated!
  • During different times of the cycle, Estrogen can
    either stimulate or inhibit other hormones

Image taken without permission from
http//bcs.whfreeman.com/thelifewire/
Slide 17 of 18
17
Female Menstrual Cycle
  • If fertilization occurs, the embryo secretes HCG
    which maintains the corpus luteum
  • Eventually cells derived from embryo will secrete
    estrogen and progesterone to take over for the
    corpus luteum
  • hCG is what is tested for in pregnancy tests
  • Birth control pills are synthetic progesterone
    and estrogen that trick the body into thinking
    the woman is pregnant no ovulation occurs

Slide 18 of 18
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