The Developing Baby The Developing Child Chapter 5 Section 1

Conception Ovum- an egg cell. An ovum is released from one of the ovaries every 28 days- part of the menstrual cycle called ovulation. Uterus- the organ in which the baby develops. During ovulation the inner lining of the uterus grows and thickens. If the ovum is not fertilized, the lining breaks down and passes out of the body- the bleeding experienced during menstruation.

Conception When the ovum is released from the ovary it travels through the fallopian tube into the uterus. Fallopian Tube- the tube that connects the ovary to the uterus. Once the ovum reaches the uterus it is ready to be fertilized. Ovum that to do not get fertilized leave the body with the menstrual flow.

Conception Sperm- the male reproductive cell. When the sperm reaches the fallopian tube, it may penetrate and fertilize the ovum. The process of the sperm fertilizing the ovum is called conception. The ovum lives for 12-24 hours. The sperm lives for 48-72 hours.

Conception Conception (fertilization) is when pregnancy begins. Ectopic Pregnancy- occurs when baby starts to grow in the fallopian tube rather than the uterus. Very dangerous for mother. Do not end in live birth.

Prenatal Development Baby’s development is grouped into 3 stages: Period of the Zygote/ Germinal Stage Period of the Embryo/ Embryonic Stage Period of the Fetus/ Fetal Stage

Period of the Zygote Zygote- the fertilized egg, is formed. This stage lasts about 2 weeks. Cell Division: Zygote begins to grow by cell division while in the fallopian tubes. Single cell > 2 cells > 4 cells > 8 cells etc...

Period of the Zygote After about 4 days of growth and slow movement the zygote reaches the opening to the uterus. Implantation: The zygote implants itself in the thickened lining of the uterus. Despite the remarkable amount of growth, at the end of this two weeks the zygote is about the size of a pin head.

Period of the Embryo 3rd – 8th week of pregnancy. Embryo- what the baby is called during this period of growth. Rapid growth and development occur in the following areas: Organs & Body Systems Amniotic Sac Placenta and Umbilical Cord

Period of the Embryo Organs & Body Systems: Cells begin to form the major systems of the body: heart, lungs, bones, & muscles. However, they are still not functional. Day 27- Neural Tube closes- later this will become the brain and spinal cord.

Period of the Embryo Organs & Body Systems con’t: The brain gradually begins to take control over the body systems. 6 weeks- brain & spine are connected allowing for baby’s first movements.

Period of the Embryo Amniotic Sac Placenta- tissue that connects the baby to the uterus. Rich in blood vessels. Supplies baby with food and oxygen. Umbilical Cord- long tube that connects the baby to the placenta. Removes carbon dioxide and waste.

Period of the Embryo Umbilical Cord: Usually stiff and firm- like a garden hose filled with water. Not typically flexible enough to loop around the fetus- but may occur in rare occasions. The placenta and umbilical cord provides for all of baby’s needs until birth.

Period of the Fetus The final and longest stage. Begins at 8th/9th week of pregnancy and lasts until birth. Fetus- what the baby is called during this period. The vocal cord, digestive system, and kidneys begin to function. Spontaneous (unplanned) movements begin to occur by the end of the 3rd month.

Period of the Fetus Making Movements: 4th-5th Month- kicks and other movements of the fetus begin to touch the walls of the uterus. Faint & infrequent fluttering- like butterflies. Gradually, movements become stronger. Baby can roll, stretch, and respond to noises through movement.

Period of the Fetus Completing Development: 7 months- baby is capable of living outside the uterus with medical help. (Age of Viability) Fetus begins to gain weight and form fat deposits that will help the baby hold body heat after delivery. Fetus goes from thin & wrinkled to smooth & round. 8th month- fetus sleeps about 90% of the day. Brain scans show REM (rapid eye movement) indicating that the baby is dreaming.

Period of the Fetus Growing Bigger: As the fetus grows, so does the amount of amniotic fluid surrounding it. The uterus also expands, causing the woman’s stomach to grow. When the fetus grows large during the last few months, it runs out of room to stretch out. It curls up in the fetal position.

Period of the Fetus Staying Active: Fetus can use all 5 senses: thumb sucking, coughing, sneezing, yawning, kicking, hiccupping, and crying. Baby is very active. 8th month- baby begins to settle into the proper position for delivery- head angled down to lead the way out of the uterus. 9th month- ready for birth!

Journal Think about the role the umbilical chord plays in nurturing the fetus. What would happen if the umbilical chord were very small or it became pinched? How would this affect the baby?