Growth & Devel. Chpt 6

Chapter 6 - Prenatal Period to 1 Year

Heredity and Environment

• Each sperm and ovum contributes 23 chromosomes to the zygote.

• The sex of the zygote is determined by the combination of X and Y chromosomes.

• Genes:

  • Dominant Genes: Genes that express their trait even if only one copy is present.

  • Recessive Genes: Genes that express their trait only when two copies are present.

Environment and Its Influences

• Factors influencing fetal development include:

  • General health of the mother: Overall physical health and any chronic conditions.

  • Diet: Nutritional balance and adequacy during pregnancy.

  • Balance of rest and exercise: Importance of physical activity and rest.

  • Avoidance of harmful substances: Avoiding tobacco, alcohol, and drugs.

  • Avoidance of teratogens: Substances that may cause developmental malformations.

  • Early prenatal supervision: Importance of regular medical check-ups during pregnancy.

Prenatal Period

• The prenatal period extends from fertilization to birth.

• Stages of Development:

  • Zygote: The fertilized egg, the earliest stage of development.

  • Morula: A solid ball of cells formed after several divisions of the zygote.

  • Blastocyst: A fluid-filled structure that implants into the uterine wall.

  • Embryo: Refers to the developing organism from implantation until the end of the eighth week.

  • Fetus: The developing organism from the ninth week until birth.

Stages of Labor

• Stage 1: Dilation

  • Dilation of the cervix and effacement (thinning) occurs.

• Stage 2: Expulsion

  • Delivery of the baby.

• Stage 3: Delivery of Placenta

  • The placenta is expelled following the birth of the baby.

Fetal Structures

• Placenta:

  • Produces hormones essential for pregnancy.

  • Transports nutrients and waste between the mother and fetus.

  • Provides protection to the fetus from various harmful agents.

• Umbilical Cord:

  • Composed of two arteries and one vein, facilitating nutrient and waste transport.

Apgar Scale

• The Apgar scale is performed at 1 minute and 5 minutes after birth to assess:

  • Color: Indicates oxygenation and overall health.

  • Reflex irritability: Response to stimuli.

  • Heart rate: Measures cardiovascular health.

  • Respiratory rate: Observes the breathing effort.

  • Muscle tone: Assesses physical tone and activity level.

Physical Characteristics of the Newborn

• Head: Examined for shape and size.

• Length and weight: Important metrics of health at birth.

• Skin: Appearance, texture, and color are assessed for health indicators.

• Genitals: Examination for normal anatomical development.

• **Face