Lesson 2

1. Lesson 2 The beginning of life

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

3. 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.

4. 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).

5. 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.

6. Stages of birth • Mild contractions, which are tightening in the muscles of the uterus signal the beginning of the first stage. Cervix begins to open. • 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. • Contractions continue after the baby is born to push the placenta out of the mother. If not completely removed, can cause infection.

7. CW/HW • P420 #1-4