Chapter 19Lesson OnePgs 486-491

The Beginning of the Life Cycle

Male Reproductive System

Female Reproductive System

Ovulation

FertilizationThe union of a male sperm cell and female egg cell is called fertilization or conception

ImplantationThe zygote has divided many times to form a cluster of cells

The zygote (fertilized egg) travels through the fallopian tube

The zygote attaches to the uterine wall (implantation)

Embryo: the cluster of cells that develop between 3-8 weeks of

pregnancy

Fetus: development of the unborn baby after eight weeks

Stages of Fetal Development

First Trimester (0-14 weeks)

Spinal cord growsBrain, ears, and

arms begin formingHeart begins to

beat12 week fetus

Stages of Fetal Development

Second Trimester (15-28 weeks)

Fetus body growsMother can feel

fetal movementEyebrows and

eyelashes developFetus can hear

20 week fetus

Stages of Fetal Development

Third Trimester (29-40 weeks)

Fetus uses all five senses

Fetus gains weightFetus becoming

crowded in uterusLungs fully develop

36 week fetus

Stages of BirthIn final weeks,

mother experiences weak contractions

Contractions become regular and stronger

The cervix dilates, preparing for the baby to exit

Labor is the final stage, the uterus contracts and pushes the baby out

Life Outside the Womb Begins!