Adult Development and Emerging Adulthood

Vocabulary flashcards summarizing key biological, psychological, and sociocultural terms related to adult development, aging, and the life phase of emerging adulthood.

Synaptic Pruning

Normal elimination of excess neurons and synapses during development that increases brain efficiency.

Gray Matter Thinning

Age-related loss of neuron bodies and synapses, beginning in the frontal lobes in early twenties.

White Matter Loss

Mid-life decline in axons, myelin, and glial cells that reduces brain connectivity.

Ventricular Enlargement

Expansion of cerebrospinal-fluid cavities that accompanies overall brain shrinkage with age.

Motor Performance Peak

Biological upper limit of speed and strength reached in early adulthood before gradual decline.

Sustained Training

Regular exercise that slows age-related losses in muscle, speed, and vital capacity.

Height Compression

Stature shrinkage after age 20 due to joint-cartilage and bone compression.

Sarcopenia

Age-related skeletal-muscle fiber atrophy and fat replacement causing 30–40 % strength loss by age 70.

Cardiac Output Decline

Reduced maximum pumping capacity as cardiac muscle weakens and arteries stiffen with age.

Vital Capacity

Maximum air exhaled after deep breath; decreases steadily after the twenties.

Reproductive Aging (Female)

Decline in ova number/quality with sharp fertility risks and chromosomal problems after age 35.

Reproductive Aging (Male)

Post-35 decreases in sperm volume and motility, plus more abnormal sperm.

Telomere

Protective DNA sequence at chromosome ends that shortens with each cell division.

Telomerase

Enzyme that rebuilds telomeres; highly active in germ, stem, and many cancer cells.

Endurance Exercise & Telomeres

Physical training that boosts telomerase activity and is linked to longer telomere length.

Diet and Telomeres

High-fiber, vitamin-rich foods lengthen telomeres; processed meats and high-PUFA diets shorten them.

Sleep and Telomeres

Habitual sleep under six hours or poor quality is associated with shorter telomeres.

Substance Use and Telomeres

Excessive alcohol or tobacco accelerates telomere shortening.

HPA Axis

Hypothalamus-pituitary-adrenal system that releases cortisol in response to stress.

Chronic Cortisol Effects

Long-term high cortisol shrinks hippocampus & prefrontal cortex, heightens amygdala activity, impairs memory.

Epigenetic Stress Effects

Stress-induced gene-expression changes (e.g., cortisol receptors) that can be inherited.

Thymus Involution

Post-adolescent shrinking of the thymus leading to reduced T-cell production and weaker immunity.

Body Mass Index (BMI)

Weight-to-height ratio used to classify underweight, healthy weight, overweight, and obesity.

Basal Metabolic Rate (BMR)

Calories burned at rest; declines with age, making weight loss harder.

Emerging Adulthood

Life phase from late teens through twenties marked by exploration and feeling "in-between" adolescence and adulthood.

Jeffrey Jensen Arnett

Psychologist who introduced and popularized the concept of emerging adulthood in the 1990s.

Five Features of Emerging Adulthood

Identity exploration, instability, self-focus, feeling in-between, and optimism/possibilities.

Social Clock

Cultural timetable specifying appropriate ages for major life milestones.

On-Time vs. Off-Time Transitions

Meeting or missing social-clock deadlines; late timing often causes stress.

Postformal Thought

Adult cognition that is relativistic, tolerant of ambiguity, and uses dialectical reasoning beyond formal operations.

Dialectical Thinking

Ability to integrate a thesis and antithesis into a higher-level synthesis.

Epistemic Cognition (Perry)

Shift from dualistic (right/wrong) to relativistic thinking during the college years.

Conscientiousness Increase

Big-Five trait that typically rises in the twenties, reflecting greater responsibility and reliability.

Agreeableness Increase

Tendency toward cooperation and kindness that often strengthens during emerging adulthood.

Risk-Taking in Emerging Adulthood

Heightened propensity for dangerous behaviors and accidental injuries compared to later adulthood.

Cohabitation

Unmarried romantic partners sharing a household; increasingly common among emerging adults.

Binge Drinking

Consuming large quantities of alcohol in a short time to become intoxicated, prevalent on college campuses.

Parent–Child Rapprochement

Renewed closeness and renegotiated roles between parents and adult children after they leave home.

Life-Expectancy Gain

Societal increase in average life span that allows delayed entry into adult commitments.

Dualistic Thinking

Early cognitive stance viewing knowledge as absolute right or wrong with no middle ground.

Sedentary Lifestyle

Modern pattern of low physical activity contributing to obesity and health decline.

Accidental Injury Trend

Highest hospitalization rates for accidents occur in early adulthood, then decline with age.

Apprenticeship Model

Structured school-to-work transition common in some countries but rare in the United States.

Vital Lung Change

Progressive decline in ability to inhale deeply and exhale forcefully, limiting endurance.