1 / 16

Survey of Pregnancy and embryonic development

Page 563. Survey of Pregnancy and embryonic development. Accomplishing Fertilization.

cady
Télécharger la présentation

Survey of Pregnancy and embryonic development

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Page 563 Survey of Pregnancy and embryonic development

  2. Accomplishing Fertilization • For fertilization to occur, sexual intercourse must occur no more than 2 days before ovulation and no later than 24 hours after, at which point the oocyte is approximately one-third of the way down the length of the uterine tube. • Sperm are attracted to the oocyte by chemicals that act as “homing devices” • It takes 1-2 hours for sperm to complete the journey up the female duct system into the uterine tubes • Only a few hundred to a few thousand sperm make it to the egg’s vicinity; the rest are destroyed by the acidic environment

  3. What is a zygote? • Fertilized egg that forms the moment the genetic material of a sperm combines with the ovum • First cell • Zygote undergoes rapid mitotic divisions; this is known as cleavage. • Daughter cells become smaller and smaller, providing a large number of cells for constructing the embryo.

  4. Embryo (developing stage until the 9th week) • By the time the developing embryo reaches the uterus is has formed into a morula • Morula- 3 days after ovulation; tiny ball of 16 cells • Free floating in uterine cavity.

  5. Embryo continues to develop until it has about 100 cells and then hollows out into a blastocyst • attaches to the endometrium by day 7 • The blastocyst secretes human chorionic gonadotropin (hCG) hormone • Maintains hormone production of the corpus luteum and prevents menses • Confirms pregnancy in urine for home pregnancy kits

  6. Three primary germ layers: • Ectoderm- nervous system, skin • Endoderm- mucosae (organ linings), lungs, liver • Mesoderm- muscle, bone, blood, heart

  7. Placenta • Temporary organ formed from a fertilized egg and mother’s uterine tissues to provide nutrients and oxygen to a developing fetus • Carries away wastes • Produces hormones of pregnancy • Attached by umbilical cord • Fully functioning by end of second month

  8. Amnion • Fluid-filled sac that surrounds the embryo • Attached to the placenta by a blood vessel-containing stalk of tissue called the umbilical cord • Ruptured when “water-breaks” prior to delivery • By the 9th week of pregnancy the embryo is known as the fetus

  9. Pregnancy • By approximately 270 days after fertilization, the fetus is said to be “full-term” and is ready to be born • Pregnancy is the period from conception to the birth of her baby

  10. Anatomical changes • Uterus enlarges pushing organs against the diaphragm, widening the ribs • Uterus reaches the xiphoid process • Relaxin hormone causes pelvic ligaments and the pubic symphysis to relax, widen, and become more flexible

  11. Physiological Changes • Nausea or “morning sickness” • Heartburn due to stomach displacement • Constipation due to limited motility of the digestive tract • Kidneys produce more urine and uterus compresses bladder • Nasal stiffness and occasional nosebleeds • Additional blood volume, increased blood pressure and pulse

  12. Development • Embryo- 1st 8 weeks of pregnancy. Fetus- 9th week to birth. • Month 1: nervous system begins; limb buds. • Month 2: 1g; large head; heart beats; bone form; digits. • Month 3: 30g; facial features; blood; sex detected. • Month 4: 100g; body elongates; human face • Month 5: .5-1lb; fetal position; quickening (muscular activity); lanugo • Month 6: 1.5lb; substantial weight gain, wrinkled skin • Month 7: 3lb; testes descend; eyes open; viable • Month 8: 5lb; subcutaneous fat; skin less wrinkled • Month 9: 7.5 lb; lanugo shed; full nails

  13. Childbirth • Childbirth aka parturition • Usually occurs within 15 days of the calculated due date (280 from last menstrual period) • Laboris the series of events that expel the infant from the uterus

  14. http://www.ewtn.com/library/prolife/pregnancy.htm • http://www.baby2see.com/gender/external_genitals.html • http://www.babycenter.com/fetal-development-week-by-week • http://www.squidoo.com/eat-human-placenta

More Related