Human Development Stages: Prenatal to Toddlerhood

• Human development occurs in eight periods: prenatal, infancy and toddlerhood, early childhood, middle childhood, adolescence, emerging and young adulthood, middle adulthood, and late adulthood.

Prenatal Period (conception to birth)

• Conception occurs with fertilization.
• Genetic and environmental factors interact.
• Basic body structures and organs develop, along with a brain growth spurt.
• Physical growth is most rapid.
• High sensitivity to environmental influences.

Infancy and Toddlerhood (birth to age 3)

• Senses and body systems become functional.
• Brain grows in complexity.
• Motor skills develop rapidly.
• Abilities to learn and remember emerge, even in early weeks.
• Symbolic thinking and problem-solving develop by the end of the second year.
• Language comprehension and use develop quickly.
• Attachments to parents and others form.
• Self-awareness develops.
• There's a shift from dependence to autonomy.
• Interest in other children increases.

Early Childhood (ages 3 to 6)

• Growth is steady, and body proportions become more adult-like.
• Appetite decreases, and sleep problems can occur.
• Handedness appears.
• Fine and gross motor skills and strength improve.
• Thinking is still egocentric, but understanding of others’ perspectives develops.
• Cognitive immaturity results in illogical ideas about the world.
• Memory and language improve.
• Intelligence becomes predictable.
• Pre-school and kindergarten experiences are common.
• Self-concept and understanding of emotions become more complex.
• Self-esteem is global.
• Independence, initiative, and self-control increase.
• Gender identity develops.
• Play becomes more imaginative and social.
• Altruism, aggression, and fearfulness are common.
• Family is central, but other children become important.

Middle Childhood (ages 6 to 11)

• Growth slows down.
• Strength and athletic skills improve.
• Respiratory illnesses are common.
• Health is generally better than at other times in life.
• Children begin to think logically but concretely.
• Memory and language skills increase.
• Cognitive gains help children benefit from formal schooling.
• Some children show special educational needs and strengths.
• Self-concept affects self-esteem.
• Coregulation happens between parent and child.
• Peers become important.

Adolescence (ages 11 to about 20)

• Physical growth and changes are rapid.
• Reproductive maturity occurs.
• Health risks arise from behavioral issues like eating disorders and drug abuse.
• Abstract and scientific reasoning develops.
• Immature thinking persists in some attitudes and behaviors.
• Education focuses on college or vocation preparation.
• The search for identity, including sexual identity, becomes central.
• Relationships with parents are generally good.
• Peer groups have positive or negative influences.

Emerging and Young Adulthood (ages 20 to 40)

• Physical condition peaks then declines slightly.
• Lifestyle choices impact health.
• Thought and moral judgments become more complex.
• Educational and occupational choices are made.
• Personality becomes relatively stable.
• Intimate relationships and personal lifestyles are established.
• Most people marry and become parents.

Middle Adulthood (ages 40 to 65)

• Sensory abilities, health, stamina, and strength deteriorate.
• Women experience menopause.
• Mental abilities peak while expertise and problem-solving skills are high.
• Creative output may decline in quantity but improve in quality.
• Career success and earning power peak for some; others experience burnout or career change.
• A sense of identity continues to develop.
• A midlife transition may occur.
• Responsibilities of caring for children and parents may cause stress.
• The launching of children results in an empty nest.

Late Adulthood (age 65 and over)

• Most people are mentally alert.
• Intelligence and memory may deteriorate.
• Most find ways to compensate.
• Retirement may offer new options.
• People develop strategies for coping with losses and impending death.
• Family and friends provide support.
• The search for meaning in life becomes central.

Conceiving New Life

• Fertilization occurs when sperm and ovum unite to produce a zygote, also called conception.
• A zygote is a single-celled organism resulting from fertilization.

Causes of Multiple Births

• Dizygotic twins come from two different ova fertilized by two different sperm and are genetically similar to regular siblings.
• Monozygotic twins result from the division of a single zygote after fertilization hence they are called identical twins.

Mechanisms of Heredity

• Heredity: Transmission of heritable characteristics from parents to offspring.
• Chemical that carries inherited instructions for the development of all cellular forms of life.
• Genetic Code: Sequence of bases within the DNA molecule governs proteins that determine the structure and functions of living cells.
• Chromosomes: Coils of DNA that consist of genes.
• Genes: Small segments of DNA located on particular chromosomes that are functional units of heredity.
• Human Genome: Complete sequence of genes in the human body.

How Sex is Determined

• Autosomes: In humans, the 22 pairs of chromosomes not related to sexual expression.
• Sex chromosomes: Pair of chromosomes that determines sex: XX in normal human female, XY in the normal human male.

Patterns of Genetic Transmission

• Alleles: Two or more forms of a gene that are at the same location on paired chromosomes and affect a trait.
• Homozygous: Possessing two identical alleles for a trait.
• Heterozygous: Possessing differing alleles for a trait.
• Dominant Inheritance: Inheritance in which a child receives different alleles, only the dominant one is expressed.
• Recessive inheritance: Inheritance in which a child receives identical recessive alleles, resulting in a nondominant trait.
• Polygenic Inheritance: Inheritance in which multiple genes at different sites on chromosomes affect a trait.

Some Birth Defects

• Alpha 1-antitrypsin deficiency: Enzyme deficiency that can lead to cirrhosis of the liver in early infancy and emphysema and degenerative lung disease in middle age.
• Alpha thalassemia: Severe anemia that reduces the blood's ability to carry oxygen; affected infants are often stillborn or die shortly after birth.
• Beta thalassemia (Cooley's anemia): Severe anemia leads to weakness, fatigue, and frequent illness, typically fatal in adolescence or young adulthood.
• Cystic fibrosis: Overproduction of mucus in the lungs and digestive tract, resulting in abnormal growth and reducing life expectancy with treatments including physical therapy, antibiotics, enzymes
• Duchenne muscular dystrophy progresses to muscle weakness and minor mental retardation.
• Hemophilia causes excessive bleeding
• Anencephaly: Absence of brain tissues where affected infants die quickly
• Spina bifida: Incompletely closed spinal cord
• Phenylketonuria (PKU): Metabolic disorder resulting in mental retardation, managed with the help of a diet
• Polycystic kidney disease: Enlarged kidneys that cause breathing problems

Sex Chromosome Abnormalities

• XYY: Males with tall stature and they tend to score low on IQ tests.
• XXX (triple X): Females with menstrual irregularities, learning disorders, and mental retardation.
• XXY (Klinefelter): Males who have reduced sterility and underdeveloped sex characteristics.
• XO (Turner): Females who are short in stature.
• Fragile X: The most common inherited form of mental retardation. Gestation: The period of development between conception and birth. Gestational age: Age of an unborn baby, is typically measured from the expectant mother's last menstrual cycle Labor starts 2 weeks before delivery where high estrogen levels stimulate the uterus. False contractions are referred to as Braxton-Hicks contractions and can happen as soon as the second trimester Stage 1, also referred to as dilation of the cervix lasts 12 to 14 hours for women having their first child while during subsequent births, the first is shorter A baby's need help by a doctor when signaling for help where doctors use suction cups to remove the child. Vaginal Delivery is the usual form of methods. Apgar scale - measurement of a newborn's condition. Brazleton Neonatal Behavioral Assessment Scale (NBAS) - measure the environmental of the newborn. Neonatal Screening for Medical Conditions Children - PKU Complications of Childbirth due to low weights, prematurity and small infants Fetal Development (in months one-six): growth is more rapid for embryos, organs develop and sex is defined in fetuses Gestational age - the period from the mother's menstrual period. Environmental Influences can cause development abnormalities. Prenatal Assessment includes ultrasound and amnocentesis A newborn can be around 20 inches long and on average weigh about 7 1/2 pounds.

Early Physical Development

• Cephalocaudal principle: Development occurs from head to tail.
• Proximodistal principle: Development occurs from the center of the body outwards. The brain is made up of: Brain and spinal cord
• The cerebellum*: Maintains balance and coordination
• The cerebrum*: largest part of the brain which shares info between each other.
• Central Nervous System* controls sensory motor activity Touch is the first for the sense to be developed, newborns are sensitive to pain. Piaget's stages are used to describe cognitive functioning Visible Imitation - Imitation with parts of one's body that one can see Intelligent behavior: Behavior that is goal-oriented and adaptive to circumstances and conditions of life. "Easy" children: generally happy and ready and to ready to accept new experiences Temperament: