ch 3. psych

Course Logistics and Academic Guidelines

• Course examinations consist of 4 chapters per quiz, with 20 total questions per quiz (5 questions per individual chapter).

• Quiz 1 is scheduled for September 20th.

• Research Paper Topic Approval must be submitted by September 27th via the designated Blackboard Discussion thread.

• Paper topics must focus on human development and reference a peer-reviewed scholarly article retrieved from the TAMIU Library database (filtered specifically by library holdings and peer-reviewed status).

• An accompanying infographic must be created and submitted based on the published templates and rubrics provided on Blackboard.

Course Overview: Prenatal Development and Pregnancy

• Pregnancy (derived from the Latin term pregnanta, meaning before birth) spans approximately 40 weeks, structured into three trimesters lasting 3 months each.

• Fertilization occurs in the upper third of the fallopian tube within $24\,\text{hours}$ of ovulation, when a male sperm cell successfully fertilizes a female egg cell.

• Chromosomal sex determination: A sperm carrying an X chromosome produces a female baby, whereas a sperm carrying a Y chromosome produces a male baby.

Germinal Period

• Covers the first 2 weeks post-conception ($0\,\text{to}\,14\,\text{days}$).

• Encompasses the creation of the zygote, rapid mitotic cell division, and final implantation into the uterine wall.

• Developmental timeline of cell cleavage and movement:

  • 24–30 hours post-fertilization: Male and female chromosomal material unite.

  • 36 hours: 2 cells.

  • 48 hours: 4 cells.

  • 3 days: Small compact ball of 16–32 cells.

  • 4 days: Hollow ball of 64–128 cells, forming a blastocyst.

  • 4–5 days: Inner cell mass forms; blastocyst remains free in the uterine cavity.

  • 6–7 days: Blastocyst attaches to the uterine wall.

  • 11–15 days: Blastocyst invades into the muscular uterine wall and becomes fully implanted.

• Structural differentiation of the blastocyst:

  • Blastocyst (inner layer of cells): Develops directly into the embryo.

  • Trophoblast (outer layer of cells): Provides nourishment, structural support, and forms protective fetal structures.

Embryonic Period and Organogenesis

• Extends from 2 to 8 weeks post-conception.

• Characterized by intensified cell differentiation, formation of primary life-support systems, and organogenesis (the rate of organ formation).

• Three Primary Germ Layers:

  • Ectoderm (Outer layer): Gives rise to the central nervous system, peripheral nervous system, sensory receptors, skin, hair, nails, appendages, and the adrenal medulla.

  • Mesoderm (Middle layer): Formulates the musculoskeletal system (bones, cartilage, muscles), circulatory and vascular system, lymphatic system, kidneys, ureters, reproductive organs, spleen, and adrenal cortex.

  • Endoderm (Inner layer): Constructs the epithelial lining of the gastrointestinal (GI) tract, liver, respiratory tract, endocrine system, urinary bladder, and urethra.

• Embryonic Life-Support Systems:

  • Amnion: A fluid-filled sac containing clear amniotic fluid that encases the floating embryo, maintaining a regulated temperature, controlled humidity, and protective cushioning.

  • Umbilical Cord: Contains two arteries and one vein; links the fetus directly to the placenta.

  • Placenta: A disk-shaped vascular organ where maternal and fetal blood vessels intertwine closely to facilitate oxygen, nutrient, and waste transfer without direct blood mixing.

Fetal Period and Prenatal Growth Milestones

• Spans from 8 to 10 weeks post-conception until birth (lasting approximately 7 months).

• Age of viability: As early as 24 weeks ($6\,\text{months}$) post-conception, the fetus has a physical chance of survival outside the uterus.

• Detailed Growth Timeline across Trimesters:

  • First Trimester:

  • Conception to 4 weeks: Length is $< \frac{1}{10}\,\text{inch}$; preliminary development of spinal cord, nervous system, GI tract, heart, and lungs; enveloped by amniotic sac; termed zygote/early embryo.

  • 8 weeks: Length is $> 1\,\text{inch}$; face forming with rudimentary eyes, ears, mouth, and tooth buds; arms and legs moving; brain forming; fetal heartbeat detectable via ultrasound; termed embryo.

  • 12 weeks: Length \n\approx 3\,\text{inches}, weight $\approx 1\,\text{oz}$; active movement of arms, legs, fingers, toes; fingerprints present; facial expressions (smiles, frowns); swallowing/sucking reflexes; sex distinguishable; active urination; termed fetus.

  • Second Trimester:

  • 16 weeks: Length $\approx 6\,\text{inches}$, weight $4\,\text{to}\,7\,\text{oz}$; strong heartbeat; thin transparent skin; downy hair (lanugo) covering body; fingernails/toenails forming; coordinated movement/rolling in amniotic fluid.

  • 20 weeks: Length $\approx 12\,\text{inches}$, weight $\approx 1\,\text{lb}$; heartbeat audible with ordinary stethoscope; thumb sucking; hiccups; visible hair, eyelashes, and eyebrows; quickening felt by mother.

  • 24 weeks: Length $\approx 14\,\text{inches}$, weight $1\,\text{to}\,1.5\,\text{lbs}$; wrinkled skin coated with protective vernix caseosa; open eyes; waste matter collecting in bowel; strong grasp reflex.

  • Third Trimester:

  • 28 weeks: Length $\approx 16\,\text{inches}$, weight $\approx 3\,\text{lbs}$; rapid body fat deposition; highly active; rudimentary breathing movements present.

  • 32 weeks: Length $16.5\,\text{to}\,18\,\text{inches}$, weight $4\,\text{to}\,5\,\text{lbs}$; distinct sleep/wake cycles; responsiveness to ambient sounds; assumption of birth position; soft flexible skull bones; iron accumulation in liver.

  • 36 to 38 weeks: Length $19\,\text{to}\,20\,\text{inches}$, weight $6\,\text{to}\,7.5\,\text{lbs}$; smooth skin; thick vernix caseosa; lanugo mostly shed; reduced activity due to space constraints; passive immunity transfer from mother.

Neural and Brain Development

• Human infants are born with approximately $20\,\text{to}\,100\,\text{billion}$ neurons.

• Four Structural Phases of Prenatal Brain Development:

  1. Neural Tube Formation: Pear-shaped neural tube develops from the ectoderm between 18 and 24 days post-conception.

  • Neural tube defects:

    • Anencephaly: Failure of the head end of the neural tube to close, resulting in underdeveloped brain tissues; uniformly fatal.

    • Spina Bifida: Incomplete closure of the lower neural tube causing spinal cord protruding and lower limb paralysis. Managed with orthopedic braces, crutches, or wheelchairs (e.g., specialized residential programs like Camp Spifida at Camp Victory near Millville, Pennsylvania, attended by individuals such as Yelyi Nordone).

  1. Neurogenesis: Massive proliferation of new immature neurons beginning around week 5 and continuing through the prenatal period.

  2. Neuronal Migration: Outward movement of neurons from their origin site to designated brain regions, occurring between 6 and 24 weeks.

  3. Neural Connectivity: Formation of axonal and dendritic connections between neurons starting around week 23.

Teratology and Hazards to Prenatal Development

• Teratogen: Any environmental agent capable of causing physical birth defects or cognitive/behavioral impairments.

• Teratology: The scientific study of the causes and mechanisms of birth defects.

• Principles determining damage severity:

  • Dose: Higher dosage correlates with greater physiological damage.

  • Genetic Susceptibility: Maternal and fetal genotypes alter susceptibility to specific agents.

  • Time of Exposure: Organogenesis during the embryonic period (weeks 3 through 8) represents the window of maximum vulnerability.

• Vulnerability Timeline by Organ System:

  • Central Nervous System: Highly sensitive during weeks 3 to 6; vulnerable to functional defects through week 38.

  • Heart: Highly sensitive during weeks 3.5 to 6.5; less sensitive through week 8.

  • Upper and Lower Limbs: Highly sensitive during weeks 4.5 to 8.

  • Eyes: Highly sensitive during weeks 4.5 to 8.5; less sensitive through week 38.

  • Ears: Highly sensitive during weeks 4.5 to 9.5; less sensitive through week 20.

  • Teeth & Palate: Highly sensitive during weeks 7 to 9; less sensitive through week 16.

  • External Genitalia: Highly sensitive during weeks 7.5 to 9; less sensitive through week 38.

• Specific Teratogenic Hazards and Manifestations:

  • Fetal Alcohol Spectrum Disorders (FASD): Caused by maternal alcohol consumption. Symptoms include facial abnormalities (wide-set eyes, flat cheekbones, smooth philtrum, thin upper lip), limb/cardiac defects, microcephaly, and intellectual disabilities. Complete abstinence from alcohol is medically recommended.

  • Prescription and Nonprescription Drugs: Antibiotics (streptomycin, tetracycline), select SSRI antidepressants, synthetic hormones (progestin, estrogen), and acne medications (Accutane) cause severe structural malformations.

  • Nicotine & Tobacco: Active or secondhand exposure leads to fetal growth restriction, low birth weight, impaired brain development, and elevated risk of ADHD.

  • Cocaine: Readily crosses the placenta, causing neurobehavioral deficits, small head circumference, cognitive delays, and acute neonatal withdrawal.

  • Marijuana: Linked to lower intelligence, low birth weight, attention deficits, and higher neonatal intensive care unit (NICU) admission rates.

  • Synthetic Opioids & Heroin: Severe risk of Neonatal Abstinence Syndrome (NAS) requiring clinical withdrawal management.

  • Radiation: High-dosage X-rays or environmental disasters (e.g., Chernobyl nuclear disaster) induce microcephaly, physical limb deficiencies, and malignancy.

  • Maternal Infectious Diseases:

  • Rubella (German Measles): Induces cardiopulmonary defects, cataracts, deafness, and microcephaly; maternal immunity screening is vital.

  • Syphilis: Causes stillbirth, severe skin lesions, and bone damage; penicillin is the sole effective fetal treatment.

  • Genital Herpes: Intrapartum exposure causes severe neurological damage or death in 25% of affected newborns; managed via Cesarean section.

  • HIV/AIDS: Transmitted transplacentally, intrapartum, or via breast milk; causes neonatal immune destruction.

  • Gestational Diabetes: Results in macrosomia (abnormally large infants) and neonatal hypoglycemia/cardiovascular issues.

Maternal and Paternal Factors in Prenatal Health

• Maternal Nutrition: Folic acid deficiency increases neural tube defect risks; high-mercury fish consumption causes neurotoxicity.

• Maternal Obesity: Correlated with elevated risk of fetal cardiovascular anomalies, neural tube defects, and stillbirth.

• Maternal Age: Adolescent mothers and mothers over 35 years exhibit higher incidences of low birth weight, Down syndrome, and mortality.

• Maternal Stress & Emotional State: Elevated maternal cortisol alters fetal brain circuitry, causing long-term executive functioning and emotional dysregulation issues.

• Paternal Factors: Paternal exposure to lead, radiation, or heavy pesticides induces sperm DNA mutations leading to miscarriages; paternal smoking causes secondhand smoke risks.

Socio-Emotional and Cultural Dimensions of Pregnancy

• Cultural paradigms dictate pregnancy practices, social accommodations (e.g., mandatory maternity leave, public seating priority), and folk beliefs (e.g., wearing metal safety pins during eclipses to avoid oral clefts, severe heartburn indicating a full head of hair, or belly elevation dictating fetal sex).

• Social support structures directly impact maternal physiological stress and fetal well-being.

The Birth Process: Stages and Attendants

• Three Stages of Labor:

  1. Stage 1 (Dilation and Effacement): Uterine contractions begin 15 to 20 minutes apart, lasting up to 1 minute, expanding the cervix to 4 inches ($10\,\text{cm}$). Lasts 6 to 12 hours in first-time mothers.

  2. Stage 2 (Birth of Fetus): Fetal head moves through the dilated cervix and birth canal; lasts 45 minutes to 1 hour, culminating in complete expulsion of the infant.

  3. Stage 3 (Afterbirth): Placental detachment, umbilical cord expulsion, and fetal membrane clearance within minutes post-delivery.

• Birth Attendants:

  • Midwives: Certified medical professionals specializing in low-risk natural childbirth; associated with lower rates of perineal tearing, hemorrhage, and systemic complications.

  • Doulas: Non-medical support professionals providing continuous emotional, physical, and educational advocacy during pregnancy and labor.

Childbirth Methods: Natural, Prepared, and Cesarean

• Natural Childbirth: Focuses on reducing pain and anxiety through education, relaxation, and physical conditioning.

• Prepared Childbirth (Lamaze Method): Incorporates specialized breathing patterns to manage pushing, combined with instruction in maternal anatomy and labor physiology.

• Cesarean Delivery: Surgical extraction of the fetus via abdominal and uterine incisions. Indicated for breech presentations (buttocks or feet emerging first), fetal distress, placenta previa/bleeding, or arrested labor progress.

Preterm and Low Birth Weight Infants

• Weight Classifications:

  • Low Birth Weight: Weight $< 5\,\text{lbs}\,8\,\text{oz}$ ($< 2500\,\text{g}$).

  • Very Low Birth Weight: Weight $< 3\,\text{lbs}\,4\,\text{oz}$ ($< 1500\,\text{g}$).

  • Extremely Low Birth Weight: Weight $< 2\,\text{lbs}\,3\,\text{oz}$ ($< 1000\,\text{g}$).

• Preterm Definition: Infants born at or prior to 35 weeks post-conception (or 37 weeks gestational age).

• Prevalence & Demographics:

  • US Preterm Birth Rates: 10.1% in 2020 compared to 8% in 2007.

  • Global Low Birth Weight Prevalence: Sudan (31%), India (30%), United States (8%), Cuba (6%), Finland (4%), South Korea (4%).

  • US Racial/Ethnic Disparities: Black Americans (14.1%), Latino Americans (7.5%), Non-Latino Whites (6.9%).

Nurturing Interventions for Preterm Infants

• Kangaroo Care: Direct skin-to-skin contact where the diapered infant rests upright against the parent's bare chest. Helps stabilize neonatal body temperature, heart rate, and respiration. Shows measurable cognitive, sleep, and cardiovascular improvements lasting 20 years post-intervention.

• Massage Therapy: Application of tactile stimulation that increases neonatal weight gain, reduces stress hormones, and shortens hospital stays.

• Music Therapy: Reduces physiological stress indicators and enhances resting oxygen saturation.

The Postpartum Period and Maternal Mental Health

• Postpartum Period ("Fourth Trimester"): Lasts approximately 6 weeks post-delivery while the maternal body returns to a pre-pregnant physiological state.

• Physiological Adjustments: Severe sleep fragmentation, exhaustion, and precipitous drops in circulating estrogen and progesterone following placental delivery.

• Psychological Conditions:

  • Postpartum Blues: Experienced by 70% of US mothers; onset at 2 to 3 days post-delivery, resolving spontaneously within 1 to 2 weeks.

  • Postpartum Depression (PPD): Affects 10% of US mothers; persistent depressive symptoms interfering with daily caregiving lasting weeks or months. Risk factors include prior clinical depression, low partner support, socioeconomic hardship, and low self-esteem. Managed via SSRI antidepressants, psychotherapy, and exercise.

  • Asymptomatic Mothers: 20% experience no adverse postpartum mood symptoms.

Physical and Neural Growth in Infancy

• Principles of Physical Growth:

  • Cephalocaudal Pattern: Growth proceeds from top (head) to bottom. Head proportion changes relative to total body length: 25% at birth, 20% at age 2, 17% at age 5, 14% at age 12, and 12% at age 25.

  • Proximodistal Pattern: Growth proceeds from the central body axis outward toward the extremities (trunks/shoulders before arms/hands, before fingers).

• Infant Brain Growth:

  • Newborn brain is 25% of its eventual adult weight; reaches 75% of adult weight by age 2.

  • Shaken Baby Syndrome: Mechanical trauma from severe shaking causing intracranial hemorrhaging, retinal tears, severe brain swelling, or death.

  • Neuroimaging Technologies: Electroencephalogram (EEG), Functional Near-Infrared Spectroscopy (fNIRS), and Magnetoencephalography (MEG).

Functional Neuroanatomy and Synaptic Plasticity

• Forebrain Organization & Lobes:

  • Frontal Lobe: Governs voluntary movement, goal-directed intentionality, critical decision-making, and personality development.

  • Occipital Lobe: Processes visual input.

  • Temporal Lobe: Mediates auditory processing, language comprehension, and memory consolidation.

  • Parietal Lobe: Integrates somatosensory information, spatial awareness, and motor coordination.

• Cerebral Hemispheres & Lateralization:

  • Lateralization: Specialization of function in one brain hemisphere. Complex cognitive tasks require extensive interhemispheric coordination across the corpus callosum.

• Microscopic Neural Architecture:

  • Dendrites receive chemical signals -> Soma/Nucleus processes electrical potential -> Axon (wrapped in insulating Myelin Sheath) transmits action potential -> Terminal Buttons release neurotransmitters across synaptic gaps.

• Blooming and Pruning:

  • Synaptic blooming: Massive overproduction of synaptic connections during the first year of life.

  • Synaptic pruning: Loss of unused neural pathways ("use-it-or-lose-it" principle) to optimize cognitive efficiency.

  • Plasticity: Extreme environmental responsiveness of the infant brain. Demonstrated by clinical cases like Michael Rubin, who underwent a left hemispherectomy at age 14 for severe refractory epilepsy and successfully recovered language and motor capacities via right hemisphere compensation.

Infant Sleep Dynamics and Sudden Infant Death Syndrome (SIDS)

• Newborn Sleep Requirement: Newborns sleep approximately 18 hours per day, characterized by high proportions of REM sleep.

• Sudden Infant Death Syndrome (SIDS): Sudden, unexplained death of an infant under 1 year during sleep.

• Risk Factors: Prone (stomach) sleeping position, soft bedding materials, exposure to environmental tobacco smoke, low birth weight, maternal smoking, and bed-sharing/co-sleeping. Supine (back) sleeping position is strongly protective.

Infant Nutrition, Motor Skill Development, and Feeding Milestones

• Energy Needs: Infants triple their birth weight and increase body length by 50% during their first year.

• Progression of Oral Motor Mechanics: Sucking and swallowing reflexes transition to mature chewing and swallowing mechanics.

• Developmental Feeding Timeline:

  • 5 Months: Introduction of semi-solid foods (e.g., rice cereal) fed via spoon using a modified sucking pattern.

  • 10 Months: Emergence of the fine motor pincer grip (thumb and index finger coordination), enabling self-feeding of small finger foods (e.g., cereal rings).

  • 18 Months: Ability to sit independently at a table and utilize a spoon to self-feed soft whole foods (e.g., blueberries).

• Comparative Nutritional Modes:

  • Breastfeeding Benefits: Transfers maternal antibodies, lowers incidence of gastrointestinal and respiratory infections, reduces SIDS risk, protects against childhood obesity and diabetes.

  • Formula Feeding Benefits: Ensures flexible feeding schedules, allows direct paternal/caregiver feeding involvement, and provides precise caloric/volume tracking.