3.2 - Physical Development Across the Lifespan

Prenatal Influences: Genetic and Environmental Factors

• Genetic Factors:

  • Phenylketonuria (PKU): A genetic disorder that prevents the breakdown of a certain amino acid, which can lead to intellectual disability if not treated.

• Tay-Sachs Disease: A fatal genetic disorder that causes the breakdown of nerve cells in the brain and spinal cord.

• Down Syndrome: A genetic disorder caused by an extra copy of chromosome 21, leading to intellectual disability and physical characteristics.

• Environmental Factors (Teratogens):

  • Maternal Illness:

    • Rubella (German Measles): Can cause blindness, deafness, heart defects, or stillbirth.

    • Syphilis: Can cause mental retardation, physical deformities, and miscarriage.

    • AIDS: Can be transmitted to the baby during pregnancy or childbirth.

  • Drug Use:

    • Illegal Drugs: Cocaine and other drugs can cause addiction in the baby.

    • Legal Drugs: Even some prescription or over-the-counter drugs can harm the fetus.

    • Fetal Alcohol Syndrome (FAS): Alcohol consumption during pregnancy can lead to physical and cognitive impairments.

  • Smoking: Reduces oxygen and nutrients to the fetus, leading to low birth weight and potential brain damage.

  • Takeaway: Teratogens are chemicals/agents that can harm the child inside of the womb.

Newborn Reflexes

• Rooting Reflex: Turning the head and opening the mouth in response to a touch on the cheek.

• Sucking Reflex: Sucking on anything that touches the lips.

• Startle (Moro) Reflex: Throwing out arms and legs, then pulling them in, in response to a loud noise or sudden movement.

• Babinski Reflex: Toes fan out when the sole of the foot is stroked.

Physical Development in Infancy and Childhood

• Happens in a similar order for all children, but the timing can differ from one child to another.

• Key Milestones:

  • Development of fine motor skills (like grasping small objects).

  • Development of gross motor skills (like crawling or walking).

• These skills develop as children grow, helping them become more independent.

• Visual Cliff Research:

  • Shows that infants have an early ability to perceive depth.

  • Provides a creative method to assess how infants respond to depth perception.

• Physical growth during infancy and childhood has a big impact on behavior and mental processes.

  • For example, as children develop motor skills, they also gain independence and the ability to explore their environment, which influences learning and cognitive development.

Maturation: The biological growth process that unfolds naturally, relatively unaffected by experience.

• Motor Development: While the sequence of motor skills (rolling over, sitting, crawling, walking) is universal, the timing can vary between individuals.

Critical or Sensitive Periods in Development

• Research shows that there are crucial times in infancy and childhood where certain skills, like language, are best developed. If these periods are missed, it might be harder to develop these skills later.

• Example: Some animals, like birds, will imprint on the first object they see, usually their mother, to ensure survival by staying close to a caregiver.

Adolescence and Puberty

• Puberty: The physical changes leading to sexual maturity, marking the start of adolescence.

• Impact on Self-Image: Early or late maturation can significantly affect how adolescents feel about themselves.

• Early Maturation:

  • Boys: May have advantages in sports and popularity but also face increased risk of delinquency.

  • Girls: May experience more social attention but also body image issues and emotional difficulties.

• Late Maturation:

  • Boys: May face teasing and self-esteem challenges.

  • Girls: May experience less social pressure but might feel left out.

• Adolescence is marked by significant physical and psychological changes.

• Key milestones include the adolescent growth spurt and puberty, where reproductive abilities develop.

• During puberty, adolescents develop primary sex characteristics (like reproductive organs) and secondary sex characteristics (like body hair, menarche in girls, and spermarche in boys).

• These physical changes can influence behavior, such as increased interest in social relationships and identity formation.

Physical Development in Adulthood

• Adulthood covers the majority of the human lifespan and includes phases of stability followed by gradual physical decline.

• This decline can affect behavior and mental processes, such as reduced mobility, slower reaction times, and changes in sensory abilities (like hearing and vision).

• Reproductive ability also changes, with women experiencing menopause and men experiencing gradual changes in fertility.

• Menopause: A natural biological process in which a woman's menstrual cycles permanently stop, typically occurring in middle age, marking the end of reproductive ability and often accompanied by symptoms like hot flashes and mood changes.