Pregnancy and Development

Pregnancy and Development

After studying this chapter, the reader should be able to:

1. Describe the process of fertilization.

2. Describe the major events of cleavage.

3. What are the functions of trophoblast cells?

4. Differentiate between an embryo and a fetus.

5. Describe the hormonal changes in the maternal body during pregnancy.

6. Describe the major events of the early periods of embryonic development.

7. When does the fetal period begin?

8. Discuss the birth process and explain the role of hormones in this process.

9. List the three blood vessels in the umbilical cord and the basic umbilical cord functions.

10. Describe the length of the neonatal period.

Overview

A basic understanding of human development promotes understanding of anatomical structures. Additionally, human development and growth mechanisms are similar to the mechanisms used in the repair of injured tissues. When a sperm cell unites with a sec-ondary oocyte, a zygote is formed. Normal pregnancy lasts 38 weeks, with a human embryo developing and growing continually before birth. Growth means an increase in size and occurs as a result of increased numbers of cells and enlargement of newly formed cells. Development includes growth and is defined as the continuous process of an individual changing from one life phase to another. The period beginning with fertilization and ending at birth is known as the prenatal period. The period beginning at birth and ending at death is known as the postnatal period.