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Introduction to Human Development

  • Overview of Lecture Topics
    • Focus on the birthing process and pregnancy.
    • Rhetorical question introduced: Why are we the way we are?

Evolutionary Perspective on Development

  • Consideration of Individual Development Patterns
    • Some individuals develop similarly to others, some partially, and some uniquely.

Charles Darwin's Contributions

  • Concept of Survival of the Fittest

    • Genes that allow better adaptation to the environment enhance reproductive success.
    • Definition of fitness according to Darwin: Ability to produce offspring that survive long enough to reproduce.
    • Key aspects include:
    • Selection of traits (gene traits being advantageous or disadvantageous).
    • Adaptation to the environment.

  • Rethinking Fitness in the Modern Context

    • Modern attributes of fitness differ from those with primal survival needs.
    • Discusses traits that were once advantageous may not be so now (e.g., aggression).
    • Emphasizes societal changes in mate selection preferences over centuries.

Genetic Contributions to Development

  • Genetic Codes from Parents
    • Upon fertilization, offspring inherits 50% traits from both biological parents.
    • Emphasis on the fertilized egg as a starting point for individuality.
Cellular Basis of Genetics
  • Genetic Code Structure
    • Progression from chromosomes to DNA to genes to proteins:
    • Chromosomes are thread-like structures containing DNA in each cell.
      • Humans have 23 pairs of chromosomes.
    • DNA is structured with base pairs:
      • Adenine (A), Thymine (T), Guanine (G), Cytosine (C).
      • The order of these bases codes genetic information.
    • Genes are segments of DNA coding for specific traits (e.g., hair color, height).
Functions of Proteins
  • Proteins as Building Blocks
    • Proteins dictate how body structures and functions manifest, underpinning growth and development.

Cellular Replication Processes

Mitosis

  • Definition: Body cell division.
  • Process described:
    • Starts with one cell and replicates to produce multiple cells (explains cellular division).
    • Generates diploid cells leading to further divisions.

Meiosis

  • Definition: Sex cell division.
  • Key differences from mitosis:
    • Generates unpaired chromosomes which later combine during fertilization.
Sex Determination
  • Importance of the 23rd Chromosome in sex determination:
    • Female: XX
    • Male: XY
  • Discussion about how the contribution of the Y chromosome from the male parent determines biological sex.

Prenatal Development Stages

Zygote Formation

  • Zygote is formed post-fertilization.
  • Half genetic contribution from mother and half from father.

Pregnancy Duration

  • Typical human gestation period: 266 days (or 38 weeks) measured from fertilization.
    • Common reference to pregnancy as 40 weeks, measured from the last menstrual period.
Stages of Pregnancy

  • Germinal Period (Weeks 1-2)

    • Rapid cell division and implantation of the zygote into the uterine wall.
    • Identification of the blastocyst (a cluster of cells).

  • Embryonic Period (Weeks 3-8)

    • Organogenesis occurs; major organs begin to form.
    • Cells differentiate into three layers:
    • Endoderm: Develops into internal organs.
    • Mesoderm: Develops into muscles and circulatory systems.
    • Ectoderm: Develops into skin and nervous system.
    • Importance of maternal health and habits during this period.

  • Fetal Period (Weeks 9-38)

    • Transition from embryo to fetus marks this period.
    • Development of structures continues; viability can be achieved around 24 weeks.

Life Support Systems for the Developing Fetus

  • Amniotic Sac: Protects and maintains temperature.
  • Umbilical Cord: Facilitates nutrient and waste exchange between mother and fetus.
  • Placenta: Acts as a filter and connection point for blood and nutrients.

Concerns During Pregnancy

Teratogens

  • Definition: Substances that can negatively impact fetal development.
  • Challenges faced by unaware expectant mothers regarding lifestyle choices that could affect fetal health (e.g., smoking, drug use).
Diagnostic Procedures in Pregnancy
  • Use of ultrasounds (sonography) for nuchal translucency screening.
  • Potential follow-up with further tests (e.g., amniocentesis, CVS, fetal MRI) if any red flags arise.

Infertility Issues

  • Causes for infertility in men and women.
    • IVF as a solution:
    • High demand and costs associated, variations include using donor eggs or sperm.

Conclusion of Lecture

  • Overview of Birth Process:
    • Stages of labor (contractions, delivery, afterbirth).
    • Complications during birth such as breech presentations and the choices regarding cesarean sections.

Postpartum Considerations

  • Utilization of the Apgar Scale after birth to assess the newborn's health:
    • Evaluates skin color, pulse rate, breathing, reflexes, and muscle tone.