Chapter 2 - Heredity, Prenatal Development, and Birth.pptx

Chapter 2: Heredity, Prenatal Development, and Birth Lifespan Development: A Psychological Perspective By Martha Lally and Suzanne Valentine-French In this chapter:  Heredity   Prenatal development   Genes and genetic influences on development Stages and milestones of prenatal developmen...

Chapter 2: Heredity, Prenatal Development, and Birth Lifespan Development: A Psychological Perspective By Martha Lally and Suzanne Valentine-French In this chapter:  Heredity   Prenatal development   Genes and genetic influences on development Stages and milestones of prenatal development Birth process  Main events and assessment of newborn Learning objectives: Heredity Define genes  Distinguish between mitosis and meiosis, genotype and phenotype, homozygous and heterozygous, and dominant and recessive  Describe some genetic disorders, due to a gene defect, and chromosomal disorders  Define polygenic and incomplete dominance  Describe the function of genetic counseling and why individuals may seek genetic counseling  Define behavioral genetics, describe genotypeenvironment correlations and genotypeenvironmental interactions, and define epigenetics  Basics of genetics: Genes  Genes = Recipes for making proteins    Proteins affect structure/function of cells Humans have about 20,500 genes (Human Genome Project) Genes located on chromosomes Basics of genetics: Chromosomes  Humans have 46 chromosomes     23 pairs First 22 pairs = Autosomes 23rd pair = Sex chromosomes 1 member of each pair inherited from each parent Basics of genetics: Chromosomes (continued)  After conception, most cells created by mitosis    The cell’s nucleus makes an exact copy of all the chromosomes Splits into two new cells Gametes formed by meiosis   Gametes = Reproductive cells (sperm or ova) Gamete’s chromosomes duplicate, and then divide twice  Results in four cells containing only half the genetic material of original gamete  Each sperm and egg possesses only 23 chromosomes and combine Figure 2.2 Mitosis vs. meiosis Genotypes and phenotypes   Genotype = All the genes a person inherits Phenotype = Features that are actually expressed    Physical features (e.g., eye color, earlobes) Internal traits (e.g., blood type, diseases) Many traits are polygenic (influenced by several genes) Genotypes and phenotypes (continued)    Alleles = Different versions of a gene Homozygous = Receive same allele from each parent Heterozygous = Receive different allele from each parent Genotypes and phenotypes (continued)     Dominant alleles expressed in phenotype even when paired with a different allele Recessive alleles expressed only when paired with identical allele Incomplete dominance – The dominant gene does not completely suppress the recessive gene Carriers – People who have inherited only one recessive allele Twins  Monozygotic (identical) twins     Fertilized egg splits apart in the first two weeks of development Two separate, but genetically identical offspring About one-third of twins are monozygotic twins Dizygotic (fraternal) twins   Two eggs (ova) are released and fertilized by two separate sperm Share the same amount of genetic material as other non-twin siblings Monozygotic and dizygotic twins Genetic disorders  Sex-linked - Defective gene on X chromosome    Recessive – Must be homozygous for this allele   More common in males if gene is recessive Hemophilia, color blindness PKU, cystic fibrosis, Tay Sachs, sickle cell disease Autosomal dominant – May be heterozygous for this allele  Huntington’s disease, Tourette’s syndrome Chromosomal abnormalities  Child inherits too many or too few chromosomes    Maternal age is most common cause Trisomy 21 (Down syndrome) – Three 21st chromosomes Sex-linked chromosomal abnormalities – Abnormality on 23rd pair Turner syndrome (XO) – Part/all of one of the X chromosomes is lost  Klinefelter syndrome (XXY) – An extra X chromosome is present in the cells of a male  Behavioral genetics   Scientific study of the interplay between genetic and environmental contributions to behavior Genotype-environment correlations – how genetic factors contribute to variations in the environment    Passive – Children inherit the genes and environments their family provides Evocative – Inherited characteristics affect environment someone experiences Active – Individuals seek out environments that support their genetic tendencies Behavioral genetics (continued)  Genotype-environment interactions – Involve genetic susceptibility to the environment   Effects of parenting style may depend on child’s genotype Epigenetics – Studies DNA modifications that affect gene expression and are passed on when cells divide  Environmental factors (e.g., stress, nutrition) affect gene expression by “switching genes on and off” Learning objectives: Prenatal development        Describe the changes that occur in the three periods of prenatal development Describe what occurs during prenatal brain development Define teratogens and describe the factors that influence their effects List and describe the effects of several common teratogens Explain maternal and paternal factors that affect the developing fetus Explain the types of prenatal assessment Describe both the minor and major complications Prenatal development: Germinal period   Begins with conception Ends when fertilized egg implants in uterine wall    Fertilized egg = Zygote 2 weeks long Cell division occurs (mitosis)  After five days of mitosis = 100 cells = blastocyst Inner layer = Embryonic disk (becomes the embryo)  Outer layer of cells = Trophoblast (becomes the support system which nourishes the developing organism)  Figure 2.5 Germinal period Prenatal development: Embryonic period   From 3-8 weeks after conception Blood vessels from trophoblast form placenta    Structure attached to the uterus Provides nourishment and oxygen from the mother to the developing embryo Connected to embryo via the umbilical cord Figure 2.6 The embryo (6-7 weeks gestational age) Prenatal development: Embryonic period (continued)  Major structures (organs, limbs, brain) start to develop   Vulnerable to damage from harmful agents Growth occurs in two patterns   Cephalocaudal – From head to tail Proximodistal – From the midline outward Prenatal development: Fetal period     From 9 weeks post-conception until birth Major structures continue to develop Growth Age of viability = First chance of survival outside uterus (24 weeks) Figure 2.8 Prenatal development age milestones Prenatal brain development   Stem cells produced along neural plate Neural groove appears during 3rd week    Eventually turns into neural tube Neural tube becomes brain and spinal cord Neurogenesis (formation of neurons) mostly completed after five months of gestation  Neurogenesis in hippocampus may be lifelong Prenatal brain development (continued)  Gray matter    Regions of brain that contain cell bodies Responsible for movement and cognitive activity White matter     Axons that form neural pathways Covered with myelin – Fatty substance that aids neurotransmission Connects gray matter areas Conducts neural impulses Teratogens   Environmental factors that can contribute to birth defects Effects depend on:     Timing – Earlier is usually worse Number – Teratogens may interact Exposure – More is usually worse Genetics – Sex, genetic vulnerability Figure 2.9 Critical periods of prenatal development Specific teratogens: Alcohol   Leading preventable cause of intellectual disability Possible outcomes:    Cognitive and behavioral problems Fetal death Fetal Alcohol Spectrum Disorders Figure 2.10 Fetal alcohol spectrum disorders Fetal Alcohol Spectrum Disorder Facial Features Facial Feature Potential Effect of Fetal Alcohol Head size Below-average head circumference Eyes Smaller than average eye opening, skin folds at corners of eyes Nose Low nasal bridge, short nose Midface Smaller than average midface size Lip and Thin upper lip, indistinct philtrum philtrum Specific teratogens: Tobacco   Includes all nicotine delivery methods (vaping, gum, patch) and secondhand smoke Possible outcomes:     Low birth weight, premature birth, miscarriage Ectopic pregnancy (fertilized egg implants itself outside of the uterus) Placenta previa (placenta lies low in the uterus and covers all or part of the cervix) Placenta abruption (placenta separates prematurely from the uterine wall) Specific teratogens: Legal and illegal drugs   Both prescription and over-the-counter medications Difficult to determine effects of illegal drugs    People may use more than one drug People may have other unhealthy behaviors Possible outcomes:    Problems with brain development Low birth weight, stillbirth, miscarriage Neonatal abstinence syndrome Specific teratogens: Pollutants   Lead, pesticides, mercury, radiation, BPA Possible outcomes  Problems with brain development Learning problems  Sensory impairment   Miscarriage, low birth weight, premature birth Specific teratogens: Diseases  Toxoplasmosis – Caused by parasite in raw meat, cat feces, dirt   Possible outcomes: Premature birth, stillbirth, brain/eye defects Sexually transmitted diseases  Possible outcomes: Transmission of STD  Premature birth, miscarriage, stillbirth, ectopic pregnancy  Specific teratogens: Diseases (continued)  Rubella (German measles)    Mostly preventable through vaccination About half of infected people have no visible symptoms Possible outcomes: Vision and hearing problems  Intellectual disability  Heart defects  Specific teratogens: Maternal age  Over 35 – Associated with increased risk of:     Genetic disorders, prematurity, miscarriage, stillbirth Diabetes and high blood pressure Older mothers typically more confident and stable Teenage – Associated with increased risk of prematurity and low birthweight   Often have poor nutrition and medical care More likely to drink, smoke, and use drugs Specific teratogens: Maternal factors  Gestational diabetes – Body can’t manage glucose appropriately   Hypertension – Too much pressure on artery walls   Associated with prematurity, stillbirth, difficult birth due to large baby size, breathing problems Associated with prematurity and low birth weight Both diabetes and hypertension endanger mother’s health Specific teratogens: Maternal factors (continued)  Rh disease – Type of anemia in baby   Rh is protein found in blood (most people Rh+) If mother is Rh- and fetus is Rh+: Mother’s immune system may react to Rh protein  Produce antibodies to destroy fetus’ red blood cells    Can be prevented by treating mother in pregnancy Can be treated with transfusion in baby after birth Specific teratogens: Maternal factors (continued)  Weight gain – Should be about 25 pounds    Too much increases risk of diabetes, hypertension, difficult birth Too little suggests baby isn’t growing properly Stress    High stress increases prematurity/low birth weight risk Poor stress management (e.g., alcohol use) Possibly associated with attention and anxiety problems Table 2.4 Weight gain during pregnancy If you were a healthy weight before pregnancy If you were underweight before pregnancy If you were overweight before pregnancy If you were obese before pregnancy  gain 25-35lbs  1-4½lbs in the first trimester and 1lb per week in the second and third trimesters  gain 28-40lbs  1-4½lbs in the first trimester and a little more than 1lb per week thereafter  gain 12-25 lbs  1-4½lbs in the first trimester and a little more than ½lb per week in the second and third trimesters  gain 11-20lbs  1-4½lbs in the first trimester and less than ½lb per week in the second and third trimesters Mothers of twins need to gain more in each category. Specific teratogens: Maternal factors (continued)  Depression – Feelings of sadness and worthlessness that interfere with daily function  Increased risk of: Prematurity and low birthweight  Poor emotional and attentional control     Many medications are possible teratogens Baby blues – Feelings of sadness lasting about a week after birth Postpartum depression – Longer-lasting depression starting in first month after birth Specific teratogens: Paternal factors  Age over 40 associated with increased risk of:    Miscarriages, autism, birth defects, achondroplasia (bone growth disorder) and schizophrenia Men more likely to smoke Men more likely to encounter environmental hazards (e.g., chemicals) at work Prenatal assessment  Ultrasound – Sound waves used to examine the fetus     Look for structural defects, growth problems, multiple fetuses Check age, location of placenta, heart rate Typically done 16-20 weeks into pregnancy May also be used to check fetal position during other tests Prenatal ultrasound Prenatal assessment (continued)     Amniocentesis – Sample amniotic fluid Chorionic villus sampling – Sample placenta Both used to check for genetic defects Recommended for:    Mothers over 35 Early tests suggest a problem Family history of genetic problems Infertility  Infertility – Inability to conceive within 12 months    Affects 10-15% of couples in the US Male factors the cause in about 1/3 of these – usually low sperm production Female factors the cause in about 1/3 of these Failure to ovulate  Pelvic inflammatory disease – Infection of reproductive organs, often caused by STD  Reproductive technology  In vitro fertilization (IVF)    Gamete intra-fallopian tube transfer (GIFT)   Implant both sperm and ova into the fallopian tube Zygote intra-fallopian tube transfer (ZIFT)    Remove eggs and fertilize outside the body Reinsert fertilized egg in the uterus Sperm and ova are fertilized outside of the body Zygote implanted in the fallopian tube May not be covered by insurance Potential complications of pregnancy   Ectopic pregnancy – Zygote implants in the fallopian tube instead of the uterus Preeclampsia (toxemia) – Increased blood pressure and leakage of protein in urine    Accounts for about half of maternal deaths in US Eclampsia – When preeclampsia causes seizures Spontaneous abortion (miscarriage)  Usually caused by chromosomal abnormalities Learning objectives: Birth      Describe how expectant parents prepare for childbirth Describe the stages of vaginal delivery Explain why a caesarean or induced birth is necessary Describe the two common procedures to assess the condition of the newborn Describe problems newborns experience before, during, and after birth Preparation for childbirth     Good health, mindset, information Choosing where to give birth Choosing health care provider Lamaze method   Teaching mother to be in control during birth Emphasis on relaxation, focus, supportive partner Stages of birth: First stage  Begins with uterine contractions    Other signs of labor:     Increase in duration, frequency, intensity Braxton-Hicks contractions = False labor Bloody discharge from the cervix Amniotic sac ruptures (“water breaks”) – but only happens now in about 15% of pregnancies Cervix dilates to 10cm (4 inches) Typically lasts 12-16 hours Stages of birth: Second stage  Baby passes through birth canal      Takes about 10-40 minutes Use combination of contractions and pushing Normally babies delivered head-first Then rotated so that shoulders come through separately Episiotomy – Incision made between the vaginal opening and anus to avoid tearing the tissue Stages of birth: Third stage   Placenta delivered within 20 minutes of birth Episiotomy stitched up (if necessary) Figure 2.16 Stages of birth for a vaginal delivery Epidurals  Epidural block – Local anesthetic injected in area around spine   Intended to relieve pain without slowing labor Used in 50% of hospital births in US Cesarean sections  Cesarean section – Surgical procedure to remove baby through abdomen  Usually done when problems occur or are expected Multiple birth  Baby not positioned correctly or too big  Mother’s or baby’s health in danger   Major surgery    Longer recovery time than vaginal birth Risk of infection May prevent later vaginal birth Induced labor  Labor produced by medical intervention    Medications Artificial rupture of the membranes Used when:      Labor has not naturally started two weeks past due date Baby has stopped growing Prenatal environment unhealthy (e.g., infection, not enough amniotic fluid, placenta separates from uterine wall) Mother’s health puts her or her baby at risk Water broke, but no contractions Neonatal assessment: Apgar test   Performed at 1 and 5 minutes after birth 5 characteristics rated from 0-2       Appearance (color) Pulse (heart rate) Grimace (reflex response) Activity (muscle tone) Respiration Score of 5 or less is cause for concern Figure 2.17 APGAR Scores Neonatal assessment: NBAS  Neonatal Behavioral Assessment Scale (NBAS)  Measures 46 aspects of functioning covering: Breathing  Motor control  Response to stimulation  Social interaction   Gives information about how to interact with babies Possible problems in newborns: Anoxia  Anoxia – Lack of oxygen to brain  Hypoxia – Low oxygen levels   Could occur during birth   Could occur during pregnancy (teratogens, maternal health) Umbilical cord kinked or prolapsed Can cause brain damage or death Possible problems in newborns: Low birth weight  Low birth weight – Less than 5.5 pounds    May lack enough fat to maintain body temperature More at risk for infection Often a sign of a poor prenatal environment Possible problems in newborns: Preterm birth  Preterm birth – Before 37 weeks gestational age     Often caused by teratogens, illness, stress May need intensive medical care May have lifelong medical or developmental problems Respiratory distress syndrome – Weak and irregular breathing Possible problems in newborns: Small-fordate  Small-for-date – Weigh less than 90% of babies of same gestational age    May be full term or preterm Associated with increased risk of death Often a sign of a poor prenatal environment