Development + Post lectures

• Embryonic period


  Sequence of events that begins with fertilization and proceeds to implantation, embryonic development (Week 1-8), and fetal development (week 9-38)
• Fertilization


  A sperm cell penetrates a secondary oocyte and their nuclei unite. The resulting cell is a zygote.
• Stages of early development


  1. Cleavage: cell division (mitosis) without growth

  2. Morula: a solid ball of cells

  3. Blastocyst: a hollow ball of cells

  4. Inner cell mass: the portion of the blastocyst that will become the embryo
• Normally, only one sperm cell fertilizes a secondary oocyte
• Capacitation


  A series of biochemical changes that occur in the male and female reproductive tract that prepare and allow a sperm to fertilize the secondary oocyte
• Zygote


  A single-cell, fertilized embryo
• Implantation


  The process where the blastocyst attaches to the uterine wall
• Extraembryonic membranes


  • Chorion: the outer sack
  • Amnion: the inner sack
  • Placenta
  • Chorionic Villus
• Placenta


  The site of exchange of nutrients and wastes between the mother and fetus. It also stores nutrients and produces several hormones to maintain pregnancy.
• Umbilical cord


  The actual connection between the placenta and embryo (and later the fetus)
• Embryonic period


  Fertilization through week 8, where the major body systems and organs are present and the limbs have formed
• Fetal period


  9th-38th week, where the fetus grows and differentiates tissues and organs that developed during the embryonic period
• Fetal heartbeat starts at ~4 weeks, human brain waves start around this time
• Maternal changes during pregnancy


  • Increased human chorionic gonadotropin (hCG)
  • Increased estrogen and progesterone
  • Increased relaxin
• Human Placental Lactogen (hPL)


  Contributes to breast development, protein anabolism, and catabolism of glucose and fatty acids
• Corticotropin Releasing Hormone (CRH)


  Produced by the placenta, thought to establish the timing of birth, and stimulates the secretion of cortisol by the fetal adrenal gland
• Labor


  The process by which the fetus is expelled from the uterus through the vagina to the outside
• Stages of true labor


  1. Dilation: Time from onset of labor to complete dilation of the cervix

  2. Expulsion: Time from complete cervical dilation to delivery of the baby

  3. Placental: Time after delivery until the placenta is expelled
• Oxytocin


  Stimulates uterine contractions
• Lactation


  The production and ejection of milk by the mammary glands
• Factors influencing milk production


  • Prolactin
  • Estrogen
  • Progesterone
• Milk ejection


  Stimulated by oxytocin
• Benefits of breastfeeding include ideal nutrition for the infant, protection from disease, and decreased likelihood of developing allergies
• The corpus luteum continues to secrete progesterone for _____ after fertilization to help maintain pregnancy and to prepare the mammary glands to secrete milk


  three to four months
• The scientific study of the sequence of events from fertilization of a secondary oocyte until the formation of an adult organism is called

  developmental biology
• While all the organ systems are present at the end of the embryonic period, most of the growth of these organ systems occurs during the fetal period. (T/F)


  True
• Down syndrome is a genetic disorder that results from


  the presence of an extra 21st chromosome.
• Alcohol in maternal blood does not cross the placenta into the fetal circulation (T/F)

  False
• Which layer of the blastocyst secretes enzymes that are used by the embryo to penetrate the uterine lining during implantation?

  syncytiotrophoblast layer
• Some types of sudden movements during exercise are difficult for pregnant women because the hormone called ____ causes certain joints, like the pubic symphysis, to become less stable.

  relaxin
• The nuclei of all human cells, except gametes, contain

  23 pairs of chromosomes
• Successive cleavages of the zygote produce a solid sphere of small cells called the


  morula
• All of the following are structures of the mammary glands EXCEPT the

  infundibulum
• The average volume of semen in a typical ejaculation is

  2.5-5ml
• The rupture of the mature (Graafian) ovarian follicle during ovulation is stimulated by a surge in the secretion of

  LH
• The funnel-shaped expanded portion of the uterine tube that contains fimbriae is called the


  infundibulum
• Menstruation is directly caused by a decrease in ovarian secretions of 


  idk
• Which phase of the female reproductive cycle is characterized by a thickening of the endometrium and development of one dominant mature (Graafian) ovarian follicle

  preovulatory phase