Chapter 2: From Conception to Birth Flashcards
Zygote
The single cell formed from the union of two gametes, a sperm and an ovum.
Gamete
A reproductive cell. In humans it is a sperm or an ovum.
Genome
The full set of genes that are the instructions to make an individual member of a certain species.
Allele
A variation that makes a gene different in some way from other genes for the same characteristics. Many genes never vary; others have several possible alleles.
Epigenetics
The study of how environmental factors affect genes and genetic expression — enhancing, halting, shaping, or altering the expression of genes.
Genotype
An organism’s entire genetic inheritance, or genetic potential.
Phenotype
The observable characteristics of a person, including appearance, personality, intelligence, and all other traits.
Methylation
- From birth to death
- egulating gametogenesis, embryonic and placental growth, as well as imprinting and epigenesis
Methyl
surrounding each gene enhances, transcribes, connects, empowers, silences, and alters genetic instructions
Microbiome
All the microbes (bacteria, viruses, and so on) with all their genes in a community; here the millions of microbes of the human body.
-most microbes are helpful, enhancing life, not harming it.
Monozygotic (MZ) twins
Twins who originate from one zygote that splits apart very early in development. (Also called identical twins.) Other monozygotic multiple births (such as triplets and quadruplets) can occur as well.
Dizygotic (DZ) twins
Twins who are formed when two separate ova are fertilized by two separate sperm at roughly the same time. (Also called fraternal twins.)
Vulnerability During Prenatal Development
The Germinal Period
An estimated 65 percent of all zygotes do not grow or implant properly and thus do not survive the germinal period.
Vulnerability During Prenatal Development
The Embryonic Period
About 20 percent of all embryos are aborted spontaneously. This is usually called an early miscarriage, a term that implies something wrong with the woman when in fact the most common reason for a spontaneous abortion is a chromosomal abnormality.
Vulnerability During Prenatal Development
The Fetal Period
About 5 percent of all fetuses are aborted spontaneously before viability at 22 weeks or are stillborn, defined as born dead after 22 weeks. This is much more common in poor nations
Vulnerability During Prenatal Development
Birth
Because of all these factors, only about 27 percent of all zygotes grow and survive to become living newborn babies.
Germinal: First 14 Days
- Conseption
- occurs when a sperm and an ovum join to form a zygote, the only time when two cells become one. This usually occurs in one of the woman’s fallopian tubes, which connects the ovary to the uterus, but it can also occur in a laboratory dish, through in vitro fertilization (IVF)
Embryo: Third week through Eighth week
After second week
- thin line called the primitive streak appears down the middle of the cell mass; it forms the neural tube 22 days after conception
- develops into the central nervous system, that is, the brain and spinal column
- head appears, as eyes, ears, nose, and mouth start to form and a minuscule blood vessel that will become the heart begins to pulsate
After fifth week
- buds that will become arms and legs emerge. Upper arms and then forearms, palms, and webbed fingers grow. Legs, knees, feet, and webbed toes, in that order, appear a few days later, each with the beginning of a skeleton
End of eighth week
-mbryo weighs just one-thirtieth of an ounce (1 gram) and is about 1 inch (½
centimeters) long. It moves frequently, about 150 times per hour, imperceptible to the woman
Cephalocaudal
Head-to-Tail
Up until adolsence, then reverse
Proximodistal
Near-to-far
Up until adolsence, then reverse
Fetus: From ninth week till birth
- encompasses dramatic change, the transformation of a tiny, sexless creature smaller than the final joint of your thumb to a newborn boy or girl about 20 inches (51 centimeters) long
- At end of embryonic period, 23rd pair of chromosomes usually produce hormones that cause the reproductive organs to develop inside (ovaries) or outside (testicles and penis) the body, also develop brain and body
3 - 6 months
- active
- heartbeat becomes stronger and faster when the fetus is awake and moving
- Digestion and elimination develop
- Fingernails, toenails, and buds for teeth form, and hair grows, including eyelashes
Age of Viability
The age (about 22 weeks after conception) at which a fetus might survive outside the mother’s uterus if specialized medical care is available.
-Birth before 22 weeks = certain death
Final Three Months
- benefits the fetal brain and body
- the neurological, respiratory, and cardiovascular systems all develop
- various lobes and areas of the brain are also established, and pathways between one area and another are forged
Down Syndrome (characteristics)
a thick tongue, round face, and slanted eyes, as well as distinctive hands, feet, and fingerprints. The hippocampus (important for memory) is usually smaller.
- may have hearing problems, heart abnormalities, muscle weakness, and short stature. They are slow to develop intellectually, especially in language, with a notable deficit in the ability to rhyme
Down Syndrome
A condition in which a person has 47 chromosomes instead of the usual 46, with 3 rather than 2 chromosomes at the 21st site. People with Down syndrome typically have distinctive characteristics, including unusual facial features, heart abnormalities, and language difficulties. (Also called trisomy-21.)
Fragile X Syndrome
A genetic disorder in which part of the X chromosome seems to be attached to the rest of it by a very thin string of molecules. The cause is a single gene that has more than 200 repetitions of one triplet.
Teratogen
drugs, viruses, pollutants, malnutrition, stress, and more — that increases the risk of prenatal abnormalities and birth complications
Times during pregnancy most critical for body formation
germinal and embryonic periods, teratogens can affect the fetal brain at any time
Fetal Alchol Syndrome (FAS)
A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and reduced intellectual ability, that may occur in the fetus of a woman who drinks alcohol while pregnant.
LBW
A body weight at birth of less than 2,500 grams (5.5 pounds)
VLBW
A body weight at birth of less than 1,500 grams (3 pounds, 5 ounces).
ELBW
A body weight at birth of less than 1,000 grams (2 pounds, 3 ounces).
Preterm
A birth that occurs two or more weeks before the full 38 weeks of the typical pregnancy — that is, at 36 or fewer weeks after conception.
SGA
A term for a baby whose birthweight is significantly lower than expected, given the time since conception. For example, a 5-pound (2,265-gram) newborn is considered SGA if born on time but not SGA if born two months early. (Also called small-for-dates.)
Reasons for LBW
-Malnutrition
Drug use
-Multiple births
Consequences of LBW
- Every developmental milestone — smiling, holding a bottle, walking, talking
- ates of cognitive, visual, and hearing impairments increase
- may cry often, pay attention less, and disobey more
Immigrant paradox
The surprising, paradoxical fact that low-SES immigrant women tend to have fewer birth complications than native-born peers with higher incomes.
Oxytocin
After 38 weeks, starts labor
Birth Positions
standing, squatting, or sitting, and give birth upright
Doula
A woman who helps with the birth process. In Latin America, traditionally a doula was the only professional who attended childbirth. Now doulas are likely to arrive at the woman’s home during early labor and later work alongside a hospital’s staff.
Ceserean Section
A surgical birth in which incisions through the mother’s abdomen and uterus allow the fetus to be removed quickly instead of being delivered through the vagina.
APGAR scale
A quick assessment of a newborn’s health, from 0 to 10. Below 5 is an emergency — a neonatal pediatrician is summoned immediately. Most babies are at 7, 8, or 9 — almost never a perfect 10.
color, heart rate, cry, muscle tone, and breathing
Kangaroo care
A form of newborn care in which mothers (and sometimes fathers) rest their babies on their naked chests, like kangaroo mothers that carry their immature newborns in a pouch on their abdomen.
Postpartum depression
A new mother’s feelings of inadequacy and sadness in the days and weeks after giving birth.
Couvade
Symptoms of pregnancy and birth experienced by fathers.
