Chapter 2 The Start of Life

Human Cell

1 human cell = 23 Chromosome pairs= 46 Chromosomes = 25,000 Genes

Fetal Monitors

A device that measures the baby's heartbeat during labor.

Down Syndrome

A disorder by the presence of an extra chromosome on the 21st pair; once referred to as mongolism, it is the most frequent cause of intellectual deficit.

Fragile X Syndrome

A disorder produced by injury to a gene on there X Chromosome, producing mild to moderate mental retardation.

Klinefelter's Syndrome

A disorder resulting from the presence of an extra X chromosome. The resulting XXY complement produces undeveloped genitals, extreme height, and enlarged breast. It is one of a number of genetic abnormalities that result from receiving the improper number of sex chromosomes.

Fetal Alcohol Syndrome (FAS)

A disorder that may include below-average intelligence and sometimes mental retardation, delayed growth, and facial deformities. FAS is now the primary preventable cause of mental retardation.

Tay-Sachs Disease

A disorder that produces blindness and muscle degeneration prior to death; there is not treatment. Usually causes death before the school age. Occurring mainly in Jews of eastern European ancestry and in French-Canadians.

Zygote

A new cell formed by the process of fertilization, in which in which two gametes-as the male(sperm) and female(ovum) reproductive cells are also called, containing huge amounts of genetic information-fuse.

X-linked genes

A number of recessive genes. They are located on the x chromosome.

In vitro fertilization (IVF)

A procedure in which a woman's ova are removed from her ovaries , and a man's sperm are used to fertilize the ova in a laboratory. The fertilized egg is then implanted in the uterus. GIFT and ZIFT are similar procedures.

Abortion

A process in which a mother voluntarily chooses to terminate pregnancy.

Ultrasound Sonography

A process in which high-frequency sound waves scene the mother's womb to produce an image of the unborn child, whose size and shape can then be assessed.

Artificial Insemination

A process of fertilization in which a man's sperm is placed directly into a woman's reproductive tract by a physician.

Anoxia

A restriction of oxygen to the baby, lasting a few minutes during the birth process, which can produce cognitive deficits such as language delays and even mental retardation due to brain cell death. Lack of oxygen for a few seconds is not harmful, but if it lasts longer it may cause serious harm.

Chorionic Villus Sampling (CVS)

A test used to find genetic defects that involving taking samples of hairlike material that surrounds the embryo by inserting a thin needle into the placenta. The test can be done between the 8th and 11th week of pregnancy.

Recessive Trait

A trait within an organism that is present, but is not expressed.

Labor: The Process of Birth Begins

About 266 days after conception, a protein called Corticotropin-releasing hormone (CRH) triggers the release of various hormones, and the process that leads to birth begins. One important hormone is Oxytocin, from the mother's pituitary gland. When the concentration of oxytocin becomes high enough, the uterus begins periodic contractions.

Can Genes Influence the Environment?

According to Sandra Scarr, there are three ways a child's genetic predisposition might influence his or her environment: -First, the children tend to focus on aspects of their environment that are more in tune with their genetic abilities. For example, an active, aggressive child may gravitate towards sports, while a reserved child may be more engaged into academics or computers. -Second, the gene-environmental influence may be more passive and less direct. For example, a particularly sports-oriented parent, who has genes that promote good physical coordination, may provide many opportunities for a child to play sports. -Finally, the genetically driven temperament of a child may evoke certain environmental influences. For instance, an infant's demanding behavior may cause parents to be more attentive to the infant's needs than they would be otherwise.

Postdelivery Hospital Stay

Accordingly, the American Academy of Pediatrics states that women should stay in the hospital no less than 48 hours after giving birth, and the US Congress passed legislation mandating a minimum insurance coverage of 48 hours for childbirth.

Bradley Method

Aka "Husband-coached-childbirth," is based on the principle that childbirth should be natural, without medication or medical interventions. To prepare for childbirth, mothers-to-be are taught muscle relaxation, breathing techniques, techniques for "trusting their bodies," and practices to promote good nutrition and exercise.

Braxton-Hicks Contractions

Aka "false labor", is when the fetus ready itself for the delivery after the fourth month.

Cesarean Delivery

Aka C-Section, the baby is surgically removed from the uterus, rather than traveling through the birth canal. If the fetus appears to be in danger, as indicated by a sudden raise in its heart rate or if blood is seen coming from the mother's vagina during labor, a cesarean may be performed. Cesarean deliveries may also be performed if the baby is in breech position, feels first in the birth canal. Breech position births, which occurs in about 1 of 25 births, place the baby at risk because the umbilical chord is more likely to be compressed, depriving the baby of oxygen.

Fertilization

Aka conception, is the joining of sperm and ovum to create a single-celled zygote from which all of us began our lives.

Preterm Infants

Aka premature infants, are born prior to 38 weeks after conception. Because they haven't had time to develop fully, preterm infants are at high risk for illness and death.

Miscarriage

Aka spontaneous abortion , occurs when a pregnancy ends before the developing child is able to survive outside the mother's womb. The embryo detaches from the wall of the uterus and is expelled. They are typically attributable to some sort of genetic abnormality.

Episiotomy

An incision sometimes made to increase the size of the opening of the vagina to allow the baby to pass.

Lamaze Birthing Technique

Based on the writings of Dr. Fernand Lamaze, this method uses breathing techniques and relaxation training. Typically, mothers-to-be attend weekly training sessions to learn to relax various parts of the body on command.

Baby's Liver

Because the liver, a critical component of the digestive system, does not always effectively work at first, almost half of newborns develop a yellowish tinge to their bodies and eyes. This "Neonatal Jaundice" is most prevalent in the preterm and low-weight neonates and is typically not dangerous. Treatment involves placing the baby under fluorescent lights or administering medicine.

Use of Anesthesia and Pain-Reducing Drugs

Certainly the ongoing discovery of pain-reducing drugs is one of the greatest advances of modern medicine, but the use of medication during childbirth has both, benefits and pitfalls. About a third of women who chose anesthesia receive epidural anesthesia, which produces numbness from the waist down. Traditional epidurals immobilize women and can prevent them from helping to push the baby. A newer form-a walking epidural or dual spinal-epidural- uses smaller needles and administers does continuously. This permits women to move more freely and has fewer side effects.

Bonding

Close physical and emotional contact between parent and child during the period immediately following birth.

Apgar Scale

Developed by Virginia Apgar, is a standard measurement system that looks for a variety of indications of good health in newborns. The scale directs attention to five basic qualities, recalled most easily by using Apgar's name as guide: Appearance (color) Pulse (heart rate) Grimace (Reflex irritability) Activity (Muscle tone) Respiration (Respiratory effort) The newborn receives a score ranging from 0-2 on each of the five qualities, for an overall score between 0-10. Most score 7 or above; the 10% that score under 7 require help to start breathing. Neonates who score under 4 need immediate, life-saving intervention.

States of Arousal

Different degrees of sleep and wakefulness, that range from deep sleep to great agitation. Caregivers become involved in easing the baby through transitions from one state to another.

Do Fathers Affect the Prenatal Environment?

Father's behavior may well have an influence. For instance, fathers-to-be should avoid smoking. Secondhand smoke may affect the health of the mother and her unborn child. The more the father smokes, the lower the birthweight of his children, same as alcohol and drug use by the father.

The Embryonic Stage

From 2 to 8 weeks. At this point the child is called embryo. One of the highlights of this stage is the development of the major organs and basic anatomy.

The Fetal Stage

From 8 weeks to birth. In this stage, the developing child becomes easily recognizable. It formally starts when the major organs have differentiated. The now called fetus, undergoes astoundingly rapid change, at the same time, the fetus is rapidly becoming more complex and makes itself known to the outside world. By 4 months a mother can feel movement of her child, and several months later others can feel the baby's kicks through the mother's skin.

The Germinal Stage

From Fertilization to 2 weeks. Is the first and the shortest stage of the prenatal period, the zygote begins to divide and grow in complexity. The fertilized egg (now called a Blastocyst) travels towards the uterus, where it becomes implanted in the uterus wall, which is rich in nutrients. The germinal stage is characterized by methodical cell division.

Prenatal Testing

If the woman is already pregnant, there are a variety of techniques to asses the health of the unborn child.

Establishing the Sex of the Child

In 22 of the 23 matched chromosome pairs, each chromosome is similar to the other member of its pair. The one exception is the 23rd pair, the one that determines the sex of the child. In females, the 23rd pair consists of two matching, relatively large X-shaped chromosomes, identified as XX. In males, the 23rd pair, one member of the pair is an X-shaped chromosome, but the other is a shorter, smaller Y-shaped chromosome, identified as XY.

Postmature Infants

Infants still unborn 2 weeks after the mom's due date. They face several risks as well as premature babies. For example the blood supply from the placenta may become insufficient to nourish the still-growing fetus. A decrease in blood to the brain may lead to brain damage. Similarly labor is riskier (for both mother and child).

Very-Low-Birthweight Infants

Infants who weigh less than 1,250 grams (around 2.25 lbs) or, regardless of weight, have been in the womb less than 30 weeks.

Low-birthweight Infants

Infants who weigh less than 2,500 grams (around 5 1/2 lbs) at birth. It accounts for most newborn deaths.

Small-for-gestional-age Infants

Infants who, because of delayed fetal growth, weigh 90 percent (or less) of the average weight of infants of the same gestational age. Newborns with weight below average are highly vulnerable to infections, and because their lungs are not fully developed, they have problems taking in oxygen, as consequence, they may experience Respiratory Distress Syndrome (RDS).

Polygenic Inheritance

Inheritance in which a combination of multiple gene pairs is responsible for the production of a particular trait.

Heterozygous

Inheriting from parents different forms of a gene for a given trait. In the case of heterozygous alleles, the dominant characteristic is expressed.

Homozygous

Inheriting from parents similar genes for a given trait.

Sickle-cell Anemia

Is a blood disorder named for the shape of the red blood cells. Symptoms include poor appetite, stunted growth, swollen stomach, and yellowish eyes. one-tenth of people of African descent carry genes that produce the disease.

Fetal Alcohol Effects (FAE)

Is a condition in which children display some, but not all, of the problems of FAS due to their mother's consumption of alcohol during pregnancy.

Operant Conditioning

Is a form of learning in which a voluntary response is strengthened or weakened, depending on its association with positive or negative response.

Hypnobirthing

Is a relatively new technique involving a form of self-hypnosis during delivery that produces a sense of peace and calm, thereby reducing pain. The basic concept is to produce a state of focused concentration in which a mother relaxes her body while focusing inward.

Teratogen

Is an environmental agent such as a drug, chemical, virus, or other factor that produces birth defect. Although the placenta is responsible from keeping teratogens from the fetus, it's not 100 percent successful.

Phenotype

Is an observable trait; the trait that is actually seen.

Habituation

Is the decrease in the response to a stimulus that occurs after repeated presentations of the same stimulus. In infants, it relies on the fact that when newborns are presented with a new stimulus, they produce an orienting response, in which they become quiet and attentive, and experiences a slowed heart rate as they take in the novel stimulus.

Stillbirth

Is the delivery of a child who is not alive, occurs in less than 1 delivery out of 100. If the death is detected before labor begins, labor is typically induced, or physicians may perform a c-section to remove the body as soon as possible.

Genotype

Is the underlying combination of genetic material present (but not outwardly visible) in an organism.

Mothers' Diet

It plays an important role in fetal development. A mother who eats a variety of diet high in nutrients is apt to have fewer complications during pregnancy, easier labor and a healthy baby.

Phenylketonuria (PKU)

It's an inherited disorder in which a child is unable to make use of "Phenylalanine", an essential amino acid present in proteins, found in milk and other foods. If untreated, PKU allows phenylalanine to build to toxic levels, causing brain damage and mental retardation. PKU is produced by a single allele, or pairs of genes. PKU illustrates the basic principles go genetic transmission.

Circumcision of Newborns Male Infant

It's the surgical removal of part or all of the foreskin from the penis, most commonly performed shortly after birth. Parents usually choose circumcision for a combination of health, religious, cultural, and traditional reasons. An estimated three-quarters of males in the US are circumcised, and worldwide the prevalence is around 30 percent.

Newborn Medical Screening

Just after birth, newborns typically are tested for a variety of diseases and genetic conditions. The American College of Medical Genetics recommends that all new borns be screened for 29 disorders, ranging from hearing difficulties and sickle-cell anemia to extremely rare conditions such as Isovaleric Acidemia (IVA), a disorder that interferes with the normal metabolism of leucine, an important amino acid. Iva and other disorders can be detected from a tiny quantity of blood drawn from an infant's heel.

Physical traits: Family Resemblances

Monozygotic twins are merely the most extreme example of the fact that the more genetically similar two people are, the more likely are to share physical characteristics. Obesity has a strong genetic component.

Mothers' Health

Mothers who have the disease or who are merely carriers of the virus may pass it on to their fetuses through the blood that reaches the placenta.

Intelligence

No other nature-nurture issue has generated more research than this one. The reason is that intelligence, generally measured as an IQ score, is a central human characteristic that differentiates humans from other species. In addition, intelligence is strongly related to scholastic success and, somewhat less strongly, to other type pf achievements. Genetics play a significant role in intelligence. In studies of both overall, and general intelligence and of specific subcomponents of intelligence, the closer the genetic link between two individuals, the greater the correspondence of their overall IQ scores.

Temperament

Patterns of arousal and emotionality that represent consistent and enduring characteristics in an individual.

The Sucking Reflex and the Swallowing Reflex

Permit the babies to ingest food right away.

Imitation

Researchers registered surprise of their own when they found that newborns could apparently imitate others' behavior. Although infants have all the facial muscles needed to express basic emotions, the appearance of such expression was assumed to be random. Research beginning in the late 1970's began to suggest a different conclusion.

Placenta

Serves as a conduit between the mother and the fetus, providing nourishment and oxygen via the umbilical chord, which also removes waste materials from the developing child. The placenta also plays a role in fetal brain development.

Mothers' Use of Alcohol and Tobacco

Smokers are two times as likely as non-smokers to have babies with abnormalities, low birthweight, mentally retarded, disruptive behavior during childhood, and smokers' babies are shorter.

Alleles

Some of the gene pairs. Genes governing traits that may take alternate forms, such as hair or eye colors.

Spontaneous Mutation

Sometimes genes, for no known reason, spontaneously change. Also, certain environmental factors, such as x-rays or even highly polluted air, may produce malformation in the genetic material. When damaged genes are passed on to a child, the result can be disastrous for physical and cognitive development.

Water Birthing

Still relatively uncommon in the US, it's a practice in which a woman enters a pool of warm water to give birth. The theory is that the warmth and buoyancy of the water is soothing, easing the length and pain of labor and childbirth, and the entry into the world is soothed for the infant, who moves from the watery environment of the womb to the birthing pool.

DNA (deoxyribonucleic acid) Molecules

Substance that determines the nature of every cell in the body and how it will work.

Genes

The basic unit of genetic information. All genes are composed of specific sequences of DNA molecules.

Third Stage of Labor

The child's umbilical chord (still attached to the neonate) and the placenta are expelled from the mother. This stage is the quickest and easiest.

Infant Mortality

The death of the child within the first year of life. The overall rate is 7.0 deaths per 1,000 live births. Infant mortality has been declining since the 1960's.

Multifactorial Transmission

The determination of traits by a combination of both genetic and environmental factors which a genotype provides a range within which a phenotype may be expressed. On the other hand, certain genotypes are relatively unaffected by environmental factors.

Genetic Counseling

The discipline that focuses on helping people deal with issues relating to inherited disorders. The counselors will use a variety of data in their work; they will take a thorough family history, looking for familiar incidence of birth defects.

Infertility

The inability to conceive after 12 to 18 months of trying to become pregnant. It is correlated with age. 15% of the couples suffer from it. In men, it results from producing too few sperm. Use of illicit drugs or cigarettes and previous bouts of STDs also increase the chances of infertility. In women, the most common cause is the failure of releasing the egg through ovulation, this may occur because of a hormone imbalance, a damaged fallopian tube or uterus, stress, abuse of alcohol or drugs.

Intracervical Insemination (ICI)

The most common type of artificial insemination, in which the sperm is placed directly into a woman's cervix.

Dominant Trait

The one trait that is expressed when two competing traits are present.

Age of Viability

The point at which an infant can survive prematurely, is about 22 weeks. Of course, the longer the baby develops after conception, the higher the chance of survival.

Amniocentesis

The process of identifying genetic defects by examining a small sample of fetal cell drain by a needle inserted into the amniotic fluid surrounding the unborn fetus. Carried out 15 to 20 weeks into pregnancy, with nearly 100 percent accuracy. The sex of the child can be determined.

Intrauterine Insemination (IUI)

The sperm is deposited into the uterus after being "washed," a process that concentrates sperm in a small amount of fluid.

Behavioral Genetics

The study of the effects of heredity on behavior and psychological characteristics. Rather than simply examining stable, unchanging characteristics such as hair or eye color, it takes a broader approach, considering how our personality and behavioral habits, are affected by genetic factors.

Neonates

The term used for newborns.

Mothers' Drug Use

The use of many kinds of drugs poses serious risks to the unborn child. Even over-the-counter remedies for common ailments can have surprisingly injurious consequences. For instance, aspirin taken for a headache can lead to fetal bleeding and growth impairments. Consider, for instance the use of marijuana, its use during pregnancy can restrict the oxygen that reaches the fetus. During early 90's, cocaine used by pregnant women led to the birth of thousands of so-called crack babies.

First Stage of Labor

The uterine contractions initially occur every 8 to 10 minutes and last around 30 seconds. As the first stage ends , the contractions reach their greatest intensity, a period known as transition. The mother's cervix fully opens, eventually expanding enough (usually around 10 cm) to allow the baby's head to go through.

Chromosomes.

There are 46 Chromosomes, that are rod-shaped portions of DNA that are organized in 23 pairs.

Childbirth Attendants: Who Delivers?

Traditionally, obstetricians, physicians who specialize in delivering babies, have been the childbirth attendants of choice. In the last few decades, more woman have chosen to use a midwife, a childbirth attendant who stays with the mother throughout labor and delivery. Midwives-most often nurses specializing in childbirth-are used primarily for pregnancies in which no complication is expected.

Monozygotic Twin

Twins who are genetically identical. Any differences in their future development can be attributed only to environmental factors.

Dizygotic Twins

Twins who are produced when two separate ova are fertilized by two separate sperm at roughly the same time. They are no more genetically similar than two siblings born at different times.

Second Stage of Labor

Typically lasts around 90 minutes, the baby's head proceeds further with each contraction.

Reflexes

Unlearned, organized involuntary responses that occur automatically in the presence of certain stimuli. Some reflexes have been rehearsed for several months before birth. Other reflexes that present themselves at birth (such as coughing, sneezing, and blinking) help the infant avoid stimuli that are potentially bothersome or hazardous.

Sensory Capabilities

When sensory experts talk of "seeing" they mean both a sensory reaction to a stimulation and a interpretation of the stimulation (the distinction between sensation and perception). Furthermore, it is tricky to pinpoint the specific sensory skills of newborns who can't explain what they are experiencing. Still, it's clear that neonates can see to some extent. Although their visual acuity is not fully developed, newborns actively pay attention to certain types of attention in their environment.

The Rooting Reflex

Which involves turning in the direction of a stimulus, (such as a light touch) near the mouth, is also related to eating. It guides the baby towards nearby sources of food, such as the mother's nipple.

Mothers' Age

Woman over 30 who give birth are at greater risk for a variety of pregnancy and birth complications than younger women. They are more apt to give birth prematurely and to have children with low birthweight. Woman who become pregnant during adolescence are more likely to have premature deliveries.