Review of Key Concepts - Chapter 12

  1. Infertility is the inability to conceive a child after a year of trying. Causes in a male include low sperm count, a malfunctioning immune system, a varicose vein in the scrotum, heat exposure, structural sperm defects, and abnormal hormone levels. Infertility in a female can be due to absent or irregular ovulation, blocked fallopian tubes, an inhospitable uterus, or antisperm secretions.
  2. Assisted reproductive technologies include artificial insemination, surrogate mothers, IVF, GIFT, ZIFT, and embryo transfer. Preimplantation genetic diagnosis screens IVF preembryos for disease-causing genes.
  3. Spontaneous abortion is common and usually occurs because an embryo or fetus has an extra or missing chromosome or is due to a hormonal or structural abnormality in the woman's reproductive tract. Babies born prematurely often experience several health problems. Maternal infection may cause premature delivery. Environmental exposures (teratogens) or abnormal genes can cause birth defects. The nature of the defect reflects which structures were in critical periods when the insult occurred. Neonatology deals with the medical problems of newborns and includes fetal treatments.
  4. Contraceptives block the meeting of sperm and oocyte or make the uterus inhospitable to implantation of a zygote. Contraceptives include hormone-containing pills, injections, or implants; barrier contraceptives; spermicides; and intrauterine devices. Vasectomy and tubal ligation are permanent methods. Experimental contraceptives target molecules involved in fertilization or manipulate the immune system.
  5. The 20 STDs have similar symptoms but are easily spread because in their early stages they may not produce symptoms.
  6. HIV causes AIDS by infecting immune system cells. HIV infects cells, replicates itself, and multiplies faster than the immune system can produce cells to fight it. As the immune system fails, opportunistic infections and cancer begin. The three stages are acute symptoms, a latent period, and then AIDS. The infection is transmitted by contact with infected body fluids.
  7. Homosexuality is likely to have biological causes.

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