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Chap.02.Revised
 

Chap.02.Revised

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Chap.02.Revised Chap.02.Revised Presentation Transcript

    • “ This multimedia product and its contents are protected under copyright law. The following are prohibited by law:
      • any public performance or display, including transmission of any image over a network;
      • preparation of any derivative work, including the extraction, in whole or part, pf any images;
      • any rental, lease, or lending of the program.”
    • The Process of Conception
      • Ovum
      • Sperm
    • The Journey of Sperm toward Ovum
    • Chromosomes
      • 23 pairs
      • DNA
      • Genes
      • X and Y chromosomes
    • Gametes (Ovum & Sperm)
      • Meiosis
      • Only 23 chromosomes
    Conception and Genetics
  • Figure 2.1
  • Conception and Genetics
    • Homozygous pair
      • When the two sets of instruction are the same at any given locus
    • Heterozygous pair
      • When the two sets of instruction are different at any given locus
    • Polygenic Inheritance
      • Many genes blend together to increase
      • the genetic outcomes seen in the phenotype
    • Multifactorial Patterns
      • Expression of traits that are influenced by both genes and environment
    • Genomic Imprinting
      • Some genes are biochemically marked at the time ova and sperm develop
    • Mitochondrial Inheritance
      • Genes passed only from mother to child
    Conception and Genetics
    • Genotype – the genetic blueprint
    • Phenotype – observable characteristics
    • Dominant-recessive pattern
      • Dominant genes always express their characteristics
      • Recessive genes come in pairs to express their characteristics
    Conception and Genetics
  • Figure 2.2
  • Figure 2.3
    • Twins
      • Identical
      • Fraternal
    • Twins in genetic research
    Conception and Genetics
    • 3 Stages of Prenatal Development
      • The Germinal Stage – the zygote
        • From conception to implantation
          • Lasts from 10 days to 2 weeks
        • Blastocyst divides into 2 sections
          • Section that will become the baby
          • Specialization of cells needed to support development –
            • Placenta
            • Umbilical cord
            • Yolk sac
            • Amnion
    Development from Conception to Birth
  • Figure 2. 4
    • 3 Stages of Prenatal Development
      • The Embryonic Stage
        • Forms the foundations of all body organs
        • Neural tube develops
        • All major organs and systems begin to develop
        • By week 7, the Y chromosome directs the development of the penis with the help of testosterone
    Development from Conception to Birth
    • 3 Stages of Prenatal Development
      • The Fetal Stage
        • Growth from 1/4 th ounce and 1 inch to
        • 7 ½ pounds and 20 inches in length
        • Refinement of all organ systems
        • Surfactant
        • Vernix
        • Age of viability - week 24
        • Engagement
    Development from Conception to Birth
    • Nervous System
      • Neural tube develops at week 4
      • Glial Cells
        • Provides the glue that holds the nervous system together
        • Helps remove debris after neuronal death
        • Segregates neurons from each other
      • The Fetal Stage Continued
  • Figure 2.5
    • Nervous System
      • Neurons
        • Dendrites
          • Major receptors of nerve impulses
        • Axons
          • Primary transmitting apparatus
        • Synapses
          • Fluid-filled gap between neurons
          • allow neurotransmitters to pass between neurons
      • Most neurons are born between 10 and 18 weeks
      • The Fetal Stage Continued
  • Figure 2.6
  • Sex Differences in Prenatal Development
    • Between week 4 and 10, males begin to secrete testosterone from primitive testes
        • Necessary to develop male genitalia
        • Lack of testosterone will “demasculinize” the male embryo
        • Too much testosterone will defeminize the female embryo
    • Prenatal hormones may influence sex differences in:
      • Brain development
      • Hormones in adolescence
      • Levels of physical aggression
      • Relative dominance of right and left hemispheres
  • Sex Differences in Prenatal Development
    • Girls
      • Slightly faster skeletal development
    • Boys
      • Slightly heavier and longer at birth
      • More vulnerable to prenatal problems
      • More likely to be aborted spontaneously
      • Have more birth injuries and birth defects
      • X-related problems may be a factor
      • Slightly more active before birth
  • Prenatal Behavior
    • Fetuses respond to sound with body movements as early as 25 weeks
    • Can distinguish between familiar and novel stimuli by 32 weeks
    • Learning may begin prenatally
      • “ The Cat in the Hat” experiment
    • Music played prenatally may lead to advanced motor and cognitive skills at six months
  • Questions to Ponder?
    • How would you deal with a risk of passing on a severe genetic illness to any child that you and your partner might have?
    • If you are having a baby, would you add music and reading to your child prenatally to your pregnancy routine? Why or why not?
    • Genetic Disorders
    • Autosomal Disorders
      • Caused by recessive genes
        • Phenylketonuria (PKU)
        • Sickle-cell disease
        • Tay-Sachs disease
      • Caused by dominant genes
        • Huntington’s disease
        • Schizophrenia
        • Migraine headaches
        • Extra fingers
    Problems in Prenatal Development
    • Genetic Disorders
    • Sex-linked Disorders
      • Red-green colorblindness
      • Hemophilia
      • Fragile-X syndrome
      • Caused by recessive gene on X chromosome
      • Boys suffer more often than girls
    Problems in Prenatal Development
  • Figure 2.7 – Sex Linked Transmission of a Recessive Disease
    • Chromosomal Errors
    • Trisomies
      • Trisomy 21 – Down Syndrome
        • Mental retardation
        • Distinctive facial features
        • Physical abnormalities
      • Maternal age is a major factor
    Problems in Prenatal Development
    • Chromosomal Errors
    • Sex Chromosome Anomalies
      • XXY – Klinefelter’s syndrome
      • XO – Turner’s syndrome
      • XXX – girls with an extra X
      • XYY – boys with an extra Y
    Problems in Prenatal Development
    • Teratogens: Maternal Diseases
    • Rubella
      • Vaccinations should be given to all children
    • HIV
    • Other sexually transmitted diseases
      • Syphilis
      • Genital herpes
      • Gonorrhea
      • Cytomegalovirus
    Problems in Prenatal Development
  • Figure 2.8
    • Other Maternal Influences
    • Chronic Illnesses
      • Heart disease, diabetes, lupus, hormone imbalances can all lead to developmental delays
    • Fetal-maternal medicine helps to manage the effects of long-term illnesses
    Problems in Prenatal Development
    • Environmental Hazards
    • Limiting exposure to mercury
    • Avoiding possible harmful chemicals
      • Lead
      • Arsenic
      • Anesthetic gasses
      • Solvents
      • Parasite-bearing substances
    Problems in Prenatal Development
    • Teratogens:
      • Substances that cause damage to an embryo
      • Each organ system is most vulnerable to harm when its development is most rapid
      • (Figure 2.8)
      • The first 8 weeks are the most dangerous
    Problems in Prenatal Development
    • Teratogens: Drugs
    • Smoking
    • Drinking
      • Fetal Alcohol Syndrome
    • Cocaine
    • Marijuana and Heroin
    Problems in Prenatal Development
    • Other Teratogens and Maternal Factors
    • Vitamin A – large doses may cause malformations of head, face, heart
    • Aspirin
    • Lead – may lead to lower IQ
      • 3–6% infants and young children have high levels of lead
      • Most are black or Hispanic children in inner cities
    Problems in Prenatal Development
    • Other Maternal Influences
    • Diet
      • Both general adequacy and the presence of certain key nutrients are essential in a pregnant woman’s diet
        • Subnutrition – a diet that is barely adequate and lacking in some essential nutrients
        • Folic acid deficiencies – risk in neural tube defects
      • Malnutrition (Especially before 3 months prenatally)
        • Low birth weight
        • Brain stunting
        • Fetal death
      • A woman’s caloric needs go up 10-20% during pregnancy
    Problems in Prenatal Development
    • Other Maternal Influences
    • Age
      • First pregnancies occurring later – 25.1 years
      • Women over 35 have higher risks for pregnancy complications
      • Teenage mothers
        • May suffer from poverty and poor prenatal care
        • Children may exhibit learning and behavior problems in school
        • Both preterm and low birth weight babies were twice as common in preteen mothers
    Problems in Prenatal Development
    • Maternal Emotions
    • Stress
      • Can change hormone levels
    • Stressful life events, emotional distress, and physical stress are linked to slight increases in problem pregnancies
    • Severely distressed mothers produce infants who grow slowly
    • Social support and counseling may help
    Problems in Prenatal Development
  • Problems in Prenatal Development
    • Poverty
      • Low birth weight or stillborn babies are more common in poor mothers
      • More likely to have earlier pregnancies
      • Good prenatal care may help overcome difficulties
  • End Show 2
    • “ This multimedia product and its contents are protected under copyright law. The following are prohibited by law:
      • any public performance or display, including transmission of any image over a network;
      • preparation of any derivative work, including the extraction, in whole or part, pf any images;
      • any rental, lease, or lending of the program.”