Lesson 2 The beginning of life

Do Now Write down what you know about how a baby gets food and oxygen as it grows inside its mother.

Fertilization Fertilization-joining together of two special cells(sperm+egg). Usually happens in the fallopian tubes. Identical twins- newely fertilized egg separates into two fertilized eggs. Same gender. Fraternal twins- two different egg cells are fertilized at the same time by two different sperm. They do not look exactly alike.

Growth during pregnancy *once after the egg is fertilized, it attaches itself to the uterus Uterus- a pear-shaped organ inside a female where a fetus is nourished. Embryo-name of the developing cells from fertilization to about the eighth week. Fetus-name of the developing organism from the eighth week to birth(9 months).

Growth inside the uterus *A fetus needs oxygen and food to grow and develop. 1)placenta- a thick, rich, lining of tissue that builds up along the walls of the uterus and connects the mother to the fetus. 2)Umbilical cord- a tube that connects the fetus and the mother’s placenta. The cord brings in food, removes waste, and once removed becomes the baby’s navel.

Stages of birth 1)Mild contractions, which are tightening in the muscles of the uterus signal the beginning of the first stage. Cervix begins to open. 2)Cervix is open to about 4 inches. Contractions are very strong and frequent. End of stage two the contractions push the baby out of the mother’s body. 3)Contractions continue after the baby is born to push the placenta out of the mother. If not completely removed, can cause infection.

CW/HW P420 #1-4