AP Unit 7 - Lesson 3: Fertilization, Implantation + Birth

What is Fertilization and Implantation?

• Fertilization: joining of egg and sperm resulting in a zygote

  • Leads to the development of an embryo

• Implantation: When the embryo travels down the fallopian tube and embeds into the endometrium

  • Further development leads to a fetus

What does the Endometrium do during this time?

• The endometrium develops the placenta and it takes over production of progresterone and estrogen which maintains the endometrium, cancelling out menstruation

What happens during childbirth? (contractions + amniotic sac)

• At the end of 9 months, hormonal changes in the mother stimulate contractions

• The amniotic sac may burst during these contractions, possibly making them stronger

What happens if a baby cannot be born vaginally and what happens to the placenta during birth?

• A Cesarean section is needed if baby cannot be born vaginally

• Placenta also needs to be birthed, any pieces that are not delivered can lead to infection

Childbirth Hormones (Oxytocin and how it affects Labour + Delivery)

• 1) Oxytocin: peptide hormone produced in the hypothalamus and post. pituitary gland involved in two positive feedback loops

  • a) Labour + Delivery

    • Fetal head exerts pressure against the cervix, which stimulates sensory nerves

    • Oxytocin stimulates uterine muscle contractions, and contractions stimulate the release of more oxytocin

Childbirth Hormones (How Oxytocin and Breastfeeding are connected)

• b) Breastfeeding

  • Nipple sucking by infant stimulates sensory nerves which signals brain to produce oxytocin

  • Oxytocin stimulates the release of milk, and milk release stimulates the release of more oxytocin and prolactin

Childbirth Hormones (Prolactin)

• Prolactin: peptide hormone that stimulates breast alveoli to produce milk

• Produced by the anterior pituitary gland following birth