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Chapter 4

Chapter 4. Prenatal, Birth, and Postnatal Periods. A Remarkable Story. Transaction between special organism Zygote Unique genetic code Specialized Environment Species Typical Fertilization in fallopian tube (oviduct) Implantation in uterus

wayne-kim
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Chapter 4

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  1. Chapter 4 Prenatal, Birth, and Postnatal Periods

  2. A Remarkable Story • Transaction between special organism • Zygote • Unique genetic code • Specialized Environment • Species Typical • Fertilization in fallopian tube (oviduct) • Implantation in uterus • At birth- billions of specialized cells capable of surviving in complex environment

  3. Three Prenatal Periods • Ovum-Germinal Period • ~ 2nd - 14th day • Embryonic Period • ~2nd-8th week • Fetal Period • 8th -38th week

  4. Ovum-Germinal Period • Starts as Zygote in fallopian tube • Mitosisproduces duplication of cells • 32 cell ball called morula • Blastula (Blastocyst) differentiates into: • Embryoblast (Inner cell mass) – develops into the embryo • Trophoblast (Outer protective layer) • Becomes amnion, chorio, placenta, allantois (umbilical cord) • Ends at implantation in the uterus wall

  5. Reproduction of Cells during Period of the Ovum • Duplication of undifferentiated cells • As cellular reproduction continues, differentiation begins • By the time it enters uterus, two distinct masses have formed

  6. Embryoblast Inner cell mass becomes the embryo Trophoblast Outer layer of cells becomes fetal membranes amnion chorion allantois Blastula (or blastocyst)- the embryoblast & trophoblast The Blastula

  7. The Blastula- Basic Structures

  8. Implantation in Uterus • Hormones prepare uterine environment • Blastula sends out tendrils • Only 1/2 of zygotes implant • Phase shift in development • A Developmental Cusp • Marks end of Germinal Period • Marks the beginning of Embryonic Period

  9. Implantation • Hormones prepare uterine environment Blastula sends out tendrils • Marks end of Germinal Period • Marks the beginning of Embryonic Period

  10. Three Embryonic Layers • Endoderm • Innermost • Becomes digestive, respiratory, internal organs (pancreas & liver) • Mesoderm • Center Layer • Muscles, bones, circ. system • Ectoderm • Outermost • Hair, Skin, CNS

  11. Period of the Fetus • Starts when all basic structures are complete • Period of refinement for survival in outside world

  12. Laws of Developmental Direction • Cephalo-caudal • Head - tail (foot) • Proximo-distal • Near-far • Gross - fine • basic - refined

  13. Teratogens • Substances or agents present prenatally that cause physical or psychological abnormalities • Laws of developmental direction mean that timing is important • Generally speaking, those having effects during embryonic development will have greater harmful outcomes

  14. Coined term for agents present during prenatal development having a beneficial outcome E.G.: AZT (Zidovudine – ZDV) HIV infection Folic Acid Neural tube disorders (spina bifida) Benefogens

  15. Teratogen Categories • Maternal Diseases • Drugs • Environmental Hazards • Maternal Characteristics

  16. Maternal Diseases • Toxoplasmosis • Cytomegalovirus (CMV) • Rubella • Genital Herpes

  17. Drugs • Cigarette Smoking • Alcohol Intake

  18. Environmental Hazards • Radiation

  19. Maternal Characteristics • Maternal Age • Malnutrition • Effect in Last Trimester • Nutritional demands of late fetus is greatest

  20. Reproductive Risk versus Caretaking Casualty • Reproductive risks - pre & perinatal events • Impaired - unimpaired • Caretaking Casualty - postnatal events • nonfacilitative - facilitative environment • vulnerable - nonvulnerable organism

  21. Postnatal Development The Remarkable Newborn

  22. Assessing the Neonate • Apgar • Brazelton Neonatal Behavioral Assessment Scale • NBAS-R • 28 behavioral • 18 Reflexes • 7 Areas: • Habituation, social interaction, motor, state organization, state regulation, autonomic system, reflexes

  23. The Ability to Respond to the Environment • Sensory Capability - Receptors • vision • hearing • smelling • tasting • feeling • Sensation - firing of receptors by stimulus • Perception - interpretation of sensory input

  24. Nativism versus Empiricism • Nativism - innate - nature • Empiricism - experience - nurture • Behavioral Systems Approach – • Perception is due to both

  25. How Do We Know the Sensory/Perceptual Capabilities of the Infant? • Common to all methods - Change in Behavior correlated with change in Stimulus

  26. Methods of Perceptual Research • Visual Preference (Fantz) • Visual Cliff (E. Gibson & Walk) • Habituation-Dishabituation • Operant Conditioning Procedures

  27. Visual Preference • Looking Chamber • Reflection of stimulus on cornea • The “Basic Problem” • Change in behavior - time gazing • Change in stimulus - different visual stimuli • Limitations - • The Coke vs. Pepsi Problem • There may be perception even though there is no preference

  28. Looking Chamber - Fantz

  29. Visual Cliff • Depth Perception • “Deep” vs. “Shallow” end • Mother entices the child to crawl • Limitations • Child or kid must be ambulatory • Overcome by monitoring heart rate of babies suspended over each end (Campos)

  30. Visual Cliff - E. Gibson

  31. Habituation-Dishabituation • Babies can’t suck & listen (watch) at same time. • Establish sucking response • Disrupt it with repeated stimulus (e.g., “Pa”) • With repetition of Pa, child habituates • sucking returns • A new stimulus (e.g., “Ba”) is introduced • If child perceives difference between Ba & Pa, sucking stops - Dishabituation

  32. Operant Procedures • Behaviors which are reinforced become more frequent • Researcher reinforces response to one stimulus and not to another • If child perceives difference between stimuli than will respond more to reinforced stimulus

  33. Operant Conditioning Procedures • Perception • Responses: e.g., head turning, sucking, kicking • Reinforcers: e.g., mother’s voice, milk, visual stimuli, heartbeat. • Memory & Cognition • Kicking mobile in presence of an X produces conjugate reinforcement • In later testing immediate kicking when X is present shows recall of contingency (remembering)

  34. Operant Conditioning Procedures • Early Perception • Dr. Seuss passages read by mothers in last trimester. • Infants suck to produce mother-read passages. • Early Socialization • Infant social referencing.

  35. Perceptual Abilities as Universal Behaviors • Some abilities are hard wired • Examples • Detect light from dark • Detect horizontal from vertical • Detect sound (phoneme) boundaries

  36. Reflexes as Universal Behaviors • Hard - Wired • Present at birth • Do not need much experience • Unlearned thus “Unconditioned” • Reflex is not a behavior but stimulus-behavior relationship

  37. Examples of Reflexes • Consummatory • Defensive • Social

  38. Consummatory Reflexes(Watson (1920) eliciting rooting reflex) • Search

  39. Defensive ReflexesWatson (1920) eliciting Babinski reflex)

  40. How Do Reflexes Change? • 1. Reflexes May Stay the Same • 2. Reflexes May Disappear • 3. Reflexes May Be Elicited by New Stimuli - Respondent Conditioning • 4. Reflexes May be Elaborated into New Behaviors - Operant Conditioning

  41. End of Chapter 4

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