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Human Reproductive SystemHuman Reproductive System
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
Oogenesis
• Occurs in the ovaries—results in the production of 1 egg (and 3 polar bodies)
• Begins when the female is an embryo —
• Oocytes form before birth and remain “frozen” in this stage indefinitely
Slide 3 of 18
Oogenesis
• Each month after puberty, one oocyte completes Meiosis I and begins Meiosis II
• Meiosis II is completed only after fertilization occurs.
Slide 4 of 18
Oogenesis
• Unequal division of cytoplasm.
• Allows for more nutrients to be available to the egg in case fertilization occurs.
Slide 5 of 18
Spermatogenesis
• Occurs in the testes in the seminiferous tubules—results in the production of 4 sperm
• Mature in the epididymis and gain motility
• Produced constantly after puberty
Slide 6 of 18
Spermatogenesis
• The sperm contains lots of mitochondria (powerhouse of the cell) —why? – The sperm have a long journey they need a
lot of energy (hence the need for lots of mitochondria)
Slide 7 of 18
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 glands
Slide 8 of 18
Male Reproductive System
• Secretions of glands contribute to the semen– produce an alkaline solution to
neutralize acidity of urethra– solution that contains food
(fructose) for the sperm.
Slide 9 of 18
Pathway of Semen
• Epididymis (testes) 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
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
Female Reproductive Hormones
• 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
Female Menstrual Cycle
• Each month, a woman’s body prepares for the possible fertilization of an egg
• Ovarian Cycle = an egg matures 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
Female Menstrual Cycle
• Ovulation – release of egg from ovary triggered by a surge of LH.
Slide 15 of 18
Female Menstrual Cycle
• Day 1 = first day of a woman’s period
• Hormonal control is complicated!– During different times of
the cycle, Estrogen can either stimulate or inhibit other hormones
Slide 17 of 18
Female Menstrual Cycle• If fertilization occurs, the embryo secretes
HcG which maintains the lining of the uterus – 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