Download Prenatal Development

Germination
Stages of Prenatal Development
Genetics
Inherited Diseases
Neonates
Germination
Humans start off as a single cell organism:
 Gametes: The male/female reproductive cells
 Zygote: Formed an hour after the sperm enters
the ovum when the two gametes fuse
 Genes: Blueprints for creating a person
 25,000 of them
 Composed of DNA molecules
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Deoxyribonucleic Acid: (DNA)
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Located along 46 chromosomes which are organized in 23 pairs.
Each parent provides 23 chromosomes.
Possible combinations are limitless.
Nearly all of the cells of the body will contain
the same 46 chromosomes as the zygote.
Prenatal Development
Typically divided into Trimesters:
 First: Conception to 3 months
 Second: 3 to 6 months
 Third: 6 to 9 months
The division of pregnancy into trimesters is arbitrary and has
no significance with regard to prenatal development.
Prenatal Development
Conception
 Occurs the moment a sperm cell fertilizes the ovum (egg
cell), forming a single-celled zygote.
Prenatal Development
Three Stages of Prenatal Development:
 Germinal (2 weeks)
Begins with conception.
Takes place in one of the fallopian tubes.
Zygote travels to the uterus and attaches
itself to the uterine wall.
 Rapid cell division occurs
 Once the zygote is successfully attached
the germinal stage is over.
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 Embryonic (6 weeks)
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Developing embryo forms all the major body systems,
organs, and structures.
Lasts from the beginning of week 3 through week 8.
Begins when the zygote attaches itself to the uterine wall.
Ends when the first bone cells form.
1 inch long and weighs 1/7 of an ounce.
Embryo already resembles a human being.
 Fetal (38 weeks)
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Lasts from week 9 (when first bone cells form) until birth.
Experiences rapid growth and further development of body structures,
organs, and systems.
Prenatal Development
 Teratogen (any agent that causes birth defects):
 Drugs (prescription, nonprescription)
 Alcohol, tobacco
 Environmental pollutants
 Infectious diseases
 Nutritional deficiencies
 Maternal stress
 Advanced age of a parent
 Severity of damage to the unborn depends on:
 Dose
 Time of exposure
 Genetic susceptibility
Teratogens and Timing of Their
Effects on Prenatal Development
Zygote
1
2
3
Embryonic period (wks)
4
5
6
7
Fetal Period (wks)
8
9
16
32
Central nervous system
Heart
Most serious
damage from
teratogens in first
2-8 wks
Arms
Eyes
Legs
Ears
Teeth
Period of susceptibility
to structural defects
Period of susceptibility
to functional defects
Palate
External genitalia
38
Prenatal Development
 Fetal alcohol syndrome:
 Abnormalities in newborn due to mother’s heavy use of
alcohol in pregnancy
 Abnormalities include:
 Facial deformities
 Defective limbs, face, heart
 Most are below-average intelligence
 Some are mentally retarded
 Moderate drinkers during pregnancy have babies who were less
attentive and alert even at 4 years of age.
Prenatal Development
 Maternal smoking can cause:
 Respiratory problems
 SIDS
 ADHD
 Low birth weight
Prenatal Development
 Illegal drugs that harm during pregnancy:
 Cocaine (norcocaine)
 Marijuana
 Heroin
 Incompatible blood types (Rh factor)
 Environmental hazards
 exposure to radiation or chemicals
 STDs, HIV infection, AIDS
 Mother to child transmission of HIV is a serious issue in Africa today.
Multiple Births
Less than 3% of all cases result in twins
 Any more is far less
Two types of twins:
 Monozygotic (Maternal twins): Identical
 Dizygotic (Fraternal): Completely different individuals
Mothers carrying multiple children run
a higher risk of premature delivery and
birth complications.
Is it a boy or a girl?
23 matched pairs of chromosomes:
 22 of them copy their pair.
 23rd chromosome:
 Determines sex
 XX: females (Two matching, relatively large chromosomes)
 XY: males
 Female contributes an X chromosome.
 Male can contribute either an X or a Y.
 If the father contributes a Y chromosome then the infant will be
male.
 Father who determines the sex of the child.
Genetics
Genetics and Traits:
 Dominant:
 Expressed trait when two competing traits are present.
 Recessive:
 Trait within an organism that is present, but is not expressed.
 Examples: Eye color, skin tone, and cleft pallet
 Genotype:
 Underlying combination of genetic material present.
 Not physically visible
 Phenotype:
 Observable trait
 The trait that is actually seen.
Genetics
 Homozygous:
 Inheriting from parents similar genes for a given trait.
 Heterozygous:
 Inheriting from parents different forms of a gene for a
given trait.
 Polygenic inheritance:
 Inheritance in which combination of multiple gene pairs
is responsible for the production of a particular trait.
 X-linked genes:
 Genes that are considered recessive and located only on
the x chromosome.
Human Genome Project
Reached in 2001:
 When molecular biologists succeeded
in mapping the specific sequence of
genes on each chromosome.
 Most important moment in the history
of genetics.
 Discovered that 99.9% of the gene
sequence is shared by all humans.
 Behavioral Genetics: Studies the effects
of heredity on behavior and psychological
characteristics
Inherited Diseases
 Down Syndrome:
 Disorder produced by the presence.
of an extra chromosome on the 21st pair.
 Most frequent cause of mental retardation.
 Fragile X Syndrome:
 Produced by injury to a gene on the
X chromosome.
 Producing mild to moderate
mental retardation.
Inherited Diseases
Sickle-cell Anemia:
 Blood disorder
 Gets its name from the shape of the red blood
cells.
 Symptoms: Poor appetite, stunted growth, swollen
stomach, and yellowish eyes.
 Most sever form of the disease
rarely live beyond childhood.
 Affects one African-American in 400.
Inherited Diseases
Tay - Sachs Disease:
 Produces blindness and muscle
degeneration prior to death
 No treatment.
 Usually causes death before its victims reach school age.
Klinefelter’s Syndrome:
 Presence of an extra x chromosome.
 Produces underdeveloped genitals,
extreme height, and enlarged breasts.
Inherited Diseases
Genetic Counseling:
 Discipline that focuses on helping people deal with
issues relating to inherited disorders.
Prenatal Testing
Ultrasound Sonography:
 High-frequency sound waves scan the
mother’s womb to produce an image of
the unborn baby.
 Size and shape can be addressed.
Chorionic villus sampling: (CVS)
 Finds genetic defects.
 Involves taking samples of hair like
material that surrounds the embryo.
Prenatal Testing
Amniocentesis:
 Identifies genetic defects
 Examines a small sample of fetal cells
drawn by a needle.
 Inserted into the amniotic fluid surrounding
the unborn fetus.
 15-20 weeks into pregnancy.
 Nearly 100 percent accurate.
Fetal Blood sampling: (FBS)
 After 18 weeks of pregnancy.
 Collects a small amount of blood from
the umbilical cord.
 Detects Down syndrome and most other
chromosome abnormalities.
Neonates
Labor: The Process of Birth Begins
 Oxytocin:
 Released by the mother’s pituitary gland.
 When the concentration of oxytocin is high enough, mother’s uterus begins
periodic contractions.
 Braxton-Hicks Contractions: (After 4th month)
 False labor
 Contractions will eventually get strong enough to force the fetus down
the birth canal until the baby enters the world.
 Cone-head (Don’t Panic!)
Neonates:
The Stages of Labor
Most labors take 16-24 hours for firstborn children.
 Duration of labor can vary depending on mother’s:
 Age
 Race
 Ethnicity
 Number of prior pregnancies
Neonates:
The Stages of Labor
Stage 1: (Longest stage)
 Uterine contractions every 8-10 minutes
 Last 30 seconds
 Toward the end contractions occur every 2 minutes
 Last 2 minutes
 As the contractions increase the cervix (separates uterus from the vagina)
becomes wider
 Eventually expanding to allow the baby’s head to pass through
 Transition: Final part of the first stage
 Fully opened cervix is usually around 10cm
Stage 2: (Approx. 90 min)
 Episiotomy: Incision made to increase the size of the vagina to help in
stretching
 Is it ethical?
 Baby’s head emerges from the mother
 Stage ends when the baby has completely left the mother
 The placenta is still inside the mother at the end of this stage
Neonates:
The Stages of Labor
Stage 3: (Quickest stage)
 Expelling of the umbilical cord and placenta
 Lasts just a few minutes
 In most cases once a baby makes it outside they spontaneously cry, which helps
them to clear their lungs of fluid
 If they don’t the child may need to be stimulated or startled to make it cry
 If it still does not:
 Immediate life saving attention may be necessary
Neonates:
Apgar Scale
Rhythm:
 Repetitive, cyclical pattern of behavior.
 Important way that behavior can become integrated in the neuronal
system and aide in the learning
 Circadian Rhythm
State:
 Degree of awareness that an infant displays to both internal and
external stimulation.
 Alertness, fussing, crying, and different levels of sleep.
 How much stimulation is necessary for a reaction
Neonates:
Apgar Scale
Apgar Scale Defined: A standard measurement system that looks for a variety of
indications of good health in newborns.
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Evaluates 5 basic qualities:
Appearance (color)
Pulse (heart rate)
Grimace (reflex irritability)
Activity (muscle tone)
Respiration (respiratory effort)
Scoring:
 From 0-2 on each of the five qualities
 Score total ranges from 0-10
 Prognosis:
 Score from 10 down to 8 means that the child is fine
 Score from 7 down to 4 will most probably need help to start breathing
 Score less than 4 means that the child needs immediate life-saving attention
The Apgar Scale
Score
Body Color
Heartbeat
Reflex
Irritability
Muscle Tone
Respiratory
Effort
0
1
2
Blue, pale
Body pink,
extremities blue
Absent
Slow – less than
Fast – 100 to 140
100 beats per min. beats per min.
No response
Grimace
Limp and
flaccid
Inactive, weak,
Strong, active
some flexion of
motion
extremities
Irregular and slow Breathing good
with normal
crying
Breathing
for no more
than 1 min.
Entire body pink
Coughing,
sneezing, crying
Neonates:
If the Child does not Pass the Apgar Scale
Average infant weights: 7 ½ pounds
 Infant Mortality: Death within the first year of
life
 Anoxia: Lack of oxygen
 If lasts longer than a few minutes can cause
mental retardation
 Stillbirth: Delivery of a child who is not alive
 Less than 1 in 100
Neonates:
If the Child does not Pass the Apgar Scale
BIRTH COMPLICATIONS:
 Preterm infants: (Premature infants) Born prior to 38 weeks after
conception
 High risk for illness and death.
 Average preterm weighs less than 5 ½ pounds
 Called Low-Birthweight Infants
 High risk for infection and RDS (Respiratory Distress Syndrome)
because of their lungs have not developed completely
 Presents great difficulty in taking in sufficient levels of oxygen
 Small-For-Gestational-Age Infants:
 Due to delayed fetal growth:
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Weigh 90% of the average weight of infants of the same
gestational age
Neonates:
If the Child does not Pass the Apgar Scale
 Very-Low-Birthweight Infants:
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Weigh less than 2 ¼ pounds
Been in womb less than 30 weeks
Their eyes are fused shut, and earlobes are hardly formed
Their skin is darkened red color
These infants rarely reach the Age of Viability:
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Point at which an infant can survive prematurely
An infant born earlier than 25 weeks has less than a 50-50 chance of survival.
 Postmature Infants: Still not born after two weeks after the mother’s
due date
 Blood supply from placenta may become insufficient
 Blood supply to the brain may be decreased (brain damage)
 Baby may be too large to make it through the birth canal
Neonates:
If the Child does not Pass the Apgar Scale
 Possible consequences of low birthweight:
 Brain injuries
 Lung and liver diseases
 Learning disabilities
 ADHD
 Lower levels in reading and math achievement
 Deficits are evident in adulthood
Neonates:
If the Child does not Pass the Apgar Scale
 About 50% of low-birthweight children are enrolled in
special education programs.
 Low birthweight is linked to asthma.
 Some defects can be improved with:
 Early speech therapy
 Intensive enrichment programs
 Kangaroo care and massage therapy
Postpartum Period
 Lasts about 6 weeks after childbirth when woman adjusts
physically and psychologically back to the prepregnant state.
 Influenced by preceding conditions and experiences
 Mother learns to care for the baby, feel good about herself and
those close to her
 Physical: hormone changes, weight loss, return to
menstruation, loss of energy or fatigue
 Psychological: feelings of depression, anxiety, coping in new
role, excessive worrying
Percentage of U.S. Women Who
Experience Postpartum Blues and
Postpartum Depression
Postpartum blues:
symptoms appear 2 to 3
days after delivery and
subside within 2 to 3
weeks
70%
20%
No symptoms
10%
Postpartum depression:
symptoms linger for weeks or
months and interfere with daily
functioning