Chapter 3 (Papalia) -...

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Chapter 3: Forming a New Life: Conception, Heredity, and Environment I. Becoming Parents A. Changing Theories of Conception § Until 20 th century, conception was believed to be inflamed by cosmic forces o Animal cultists: sperm contained people o Ovists: ovaries contained people o Walff: embryos aren’t preformed and both parents equally contribute § fertilization o Union of sperm and ovum to produce a zygote o also called conception § How Conception Occurs o Girls have 2 million ova in their ovaries at birth, each contained in a follicle o During ovulation, a mature follicle is ruptured and expelled from the ovary o Ovum is swept through the fallopian tube toward the uterus o Several hundred million sperm are produced in the testicles each day. o Sperm enter the vagina through ejaculation and attempt to reach the cervix o A few will arrive in the fallopian tubes where fertilization takes place § zygote o One-celled organism resulting from fertilization B. Infertility § Definition o Inability to conceive after 12 months of trying o 7% of US couples o Women’s fertility begins to decline in the late 20’s o Men’s fertility begins to decline in the late 30’s § Causes o Low sperm production - 60-200 per ejaculation is too low - Duct may be blocked, or sperm are unable to “swim” well enough o Blockage of the fallopian tubes o Failure to produce ova or normal ova o Mucus in the cervix o Disease of the uterine lining § Treatments o Hormone treatment o Drug therapy § Increased high-risk birth
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More production of sperm with chromosomal abnormalities o Surgery § Chance of success after 18-24 months is high C. Assisted Reproduction Technology (ART) § In Vitro Fertility (IVF) o Most common; Leslie Brown o Fertility drugs increase ova production o Surgically remove ova and fertilize in a laboratory dish o Several embryos are implanted in uterus o Increased likelihood of multiple births (premature) § In Vitro Maturation (IVM) o Performed earlier in the monthly cycle o Makes hormone injections unnecessary o Diminishes the likelihood of multiple births o Harvest 30-50 developing follicles before ovulation o Let the follicles mature in the laboratory § Male Infertility o Intra-Cytoplasmic Sperm Injection (ICSI) § For severe male infertility § Injection of a single sperm into the ovum o Artificial Insemination § Injection of sperm into a woman’s vagina, cervix, or uterus § For low sperm production in men o Artificial Insemination by a Donor (AID) § Ovum transfer o A fertilized donor egg is implanted in the mother’s uterus § Blastocyst transfer o The fertilized ovum is kept until it grows to the blastocyst stage § Gamet Intrafallopian Transfer (GIFT) or Zygote Intrafallopian Transfer (ZIFT) o Either the egg and sperm or the fertilized egg are inserted into the fallopian tube § Surrogate motherhood § Artificially conceived children o No major difference in development o In ICSI, higher rate of congenital urological and kidney
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This note was uploaded on 10/17/2010 for the course PSYC 203 taught by Professor Michelecarter during the Fall '09 term at Tompkins Cortland Community College.

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Chapter 3 (Papalia) -...

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