Chapter 2 Prenatal Development, Pregnancy, and Birth

Question 1

Identify the structures involved in and the process of fertilization:

Answer 1

• Structures Involved:
  
  • Notice that the female system has several parts:
    
    • Center stage is the uterus, the pear-shaped muscular organ that carries the baby to term.
    • The uterus is lined with a velvety tissue, the endometrium, which thickens in preparation for pregnancy and, if that event does not occur, sheds during menstruation.
    • The lower section of the uterus is the cervix.
      
      • During pregnancy, this thick uterine neck must perform an amazing feat: Be strong enough to resist the pressure of the expanding uterus; be flexible enough to open fully at birth.
    • Branching from the upper ends of the uterus are the fallopian tubes.
      
      • These slim, pipelike structures serve as conduits to the uterus.
    • The feathery ends of the fallopian tubes surround the ovaries, the almond-shaped organs where the ova, the mother’s egg cells, reside.
• Process of Fertilization:
  
  • The pathway that results in fertilization—the union of sperm and egg—begins at ovulation.
    
    • In contrast to females, whose ova are all mainly formed at birth, the testes—male structures comparable to the ovaries—are continually manufacturing sperm.
  • During sexual intercourse, these cells are expelled into the vagina, where a small proportion enter the uterus and wend their way up the fallopian tubes. What happens now is a team assault.

The sperm drill into the ovum, penetrating toward the center. Suddenly, one reaches the innermost part. Then the chemical composition of the ovum wall changes, shutting out the other sperm. The nuclei of the male and female cells move slowly together. When they meld into one cell, the landmark event called fertilization has occurred.

Question 2

Describe what happens genetically when the sperm and ovum unite.

Answer 2

• The answer lies in looking at chromosomes, ropy structures composed of ladder-like strands of the genetic material DNA. Arrayed along each chromosome are segments of DNA called genes, which serve as templates for creating the proteins responsible for carrying out the physical processes of life.
• Every cell in our body contains 46 chromosomes—except the sperm and ova, each of which has half this number, or 23.
• When the nuclei of these two cells, called gametes, combine at fertilization, their chromosomes align in pairs to again comprise 46. So nature has a marvelous mechanism to ensure that each human life has an identical number of chromosomes, and every human being gets half of its genetic heritage from the parent of each sex.
• Because each ovum carries an X chromosome, our father’s contribution determines the baby’s sex. If a lighter, faster-swimming, Y-carrying sperm fertilizes the ovum, we get a boy (XY). If the victor is a more resilient, slower-moving X, we get a girl (XX).

Question 3

Describe the stages of prenatal development (timing and major developments).

Question 4

Describe the principles of prenatal development.

Question 5

Define the age of viability and describe its importance.

Question 6

Summarize the woman’s experience during each of the trimesters during pregnancy.

Question 7

Describe how work and partner issues can impair the pregnancy experience.

Question 8

Describe the feelings of fathers-to-be.

Question 9

Name the main teratogenic threats during the first and second trimesters. Include the basic teratogenic principles.

Question 10

Outline the impact of smoking, excessive alcohol, and prenatal stress on fetal development.

Question 11

Describe Down syndrome and genetic disorders.

Question 12

Describe genetic counseling and the different prenatal diagnostic tests.

Question 13

Define infertility and describe ART.

Question 14

Describe the stages of birth.

Question 15

Contrast natural childbirth and c-sections.

Question 16

Describe other birth options, past and present (doula, Lamaze, etc.).

Question 17

Describe the Apgar scale.

Question 18

Describe threats to development just after birth.

Question 19

Outline trends in infant mortality in the developed and developing worlds.