Prenatal Development is divided into ___ main periods. The first two weeks of development are called the ____ period; the __ week through the ___ week is known as the ___ period; and from this point until birth is the _____ period.
3; germinal; 3-8; embryonic;fetal
Once clusters of cells begin to take on distinct characteristics, the cell mass is called a ______. About one week after conception, the multiplying cells seperate into outer cells that will become the _____ and inner cells form the nucleus that will become the _______.
blastocyst; placenta; embryo
The next significant event is the burrowing of the zygote into the lining of the uterus a process called _____. This process _______ automatics.
implantation; is not
At the begining of the period of the embryo a thin line down the middle of the developing individual forms a structure that will become the _____ ______, which becomes the ____ ____ and eventually will develop into the ___ ___ ___.
primitive streak; neural-tube; central nervous system
Eight weeks after conception, the embryo weighs about ______ and is about ________ in length.From the start of the ninth week after conception until birth, the organism is called the ______.
1/30 ounce(1 gram); 1 inch; fetus
The genital organs are fully formed by _____weeks. If the fetus has a ______ chromosome, the ______ genes on this chromosome sends a signal that development of the ______ sex organs. Without that gene, no signal is sent and the fetus develop _____ sex organs.
12;Y; SRY; male; female
By the end of the _______ month, the fetus is fully formed, weighs approximately _____, and is about ____ long. These figures ____ from fetus to fetus.
3rd; 3 ounces; 3 inches; vary
During the fourth fifth and sixth month the brain increases in size by a factor of _____. The brain develops neurons in a process called ______ and new connections between them in a process called ________. This neurological maturation is essential to the regualtion of such basic body functions as _____ and _______.
six; neurogenesis; synaptogenesis; breathing; sucking
The age at which the fetus has some chance of surviving outside the uterus is called ____ ___ ___, which occurs about ____ weeks after conception. This barrier _____ been reduced by advances in neonatal care, probably because maintaining life depends on some _____ response.
age of viability; 22; has not; brain
At about _____ weeks after conception, brain wave patterns begin to resemble the ___ -___ cycles of a new born.
At 28 weeks old fetus typically weighs about ____ and has about a ____ percent chance of survival .
3 pounds; 95
Three crucial aspects of development in the last month of prenatal life are maturation of the ____,____, and _____ systems.
neuroligical; respitory; cardiovascular
By full term, brain growth is so extensive that the brains advanced outer layer, called the ___ forms several folds in order to fit into the skull.
In the final ____ months, the fetus hears amny sounds, including, the mother's ____ and ___ as well as her ______.
three; heartbeat; voice; smells
I weigh about 3 lbs. and my brain is developing well as a result of the processes of ______ and _____. I am a _____.
neurogenesis; synoptses; fetus
Karen and brad report to their neighbors that , 6 weeks after conception a sonagram will reveal their babies sex organs, they are skeptical of this because...
the fetus does not begin to develop female sex organs until 8 weeks
Harmful agents and conditions that can result in birth defects called ______ include ________________________.
teratogans; viruses, drugs, chemicals; pollutants; extreme stree and maturation
Substance that impair the childs action and intellect by harming the brain are called ____ _____. Approx. ____ % of all children are born with behavioral difficulties that could be connected to damage done during the prenatal period.
behavioral teratogans; 20
The study of birth defects is called ____; it is science of _____ _____. As such it attempts to evalutate the factors that can make prenatal harm more or less likely to occure.
teratology; risk analysis
Three crucial factors that determine whether a specific teratogan will cause harm and of what nature are the _____ of exposure, the _____ of exposure and the developing organsisims ______ _____ to damage from the substance.
timing; amount; genetic vulnurability
The time when a particular part of the body is most suseptible to teratogenic damage is called its _________. For physical structure and form this is the netire period of the ______. However for ____ teratogans the entire prenatal period is critical.
critical period; embryo; behavioral
Some teratogans have a _____ effect- that is, the substances are harmless until exposure reaches a certain level. Others have an ______ effect, which occurs when some teratogans taken together make them more harmful then when taken seperately.
Fraternal twins, who share half their genes, ______ have the same abnormalities if exposed to the same teratogans. This suggests the existance of both ____ and ____ genes.
will not; protective; volnurable
Genes are also known to effect the likelihood of neural-tube defects such as _____ ______ or _____. These defects occur more commonly in certain groups. However if pregant women consume extra _____ ____, her embryo would get enough vitamin B to develop normally.
spina bifidia; microcephaly; ethnic; follic acid
Genetic vulnurability is also related to the sex of the developing organism. Generally ______ embryos and fetuses are more volnurable to teratogans. This sex also has more frequent ______ ____ and higher rate of birth defects ____ ____ and other behavior problems.
male' spontaneous abortion; learning disabilities
Women are advised to avoid all _________ before becoming pregant. Prenatal development can also be impaired by _____ _____.
drugs; chemicals in pestacides, constructionmaterials and cosmetics; prescription drugs
High dose of alchohal during pregancy may cause ______ _____ _____. A milder condition that involves emotional and cognitive problems in older children is ______ ______ ________.
fetal alchohal syndrome; fetal alchohal effects
One advantage of early prenatal care is protection against ______. An image of the fetus is called _____, allows doctors to see if the fetus is developing normally.
A number of tests are preformed routinely to determine wether a prenancy is problematic. Among them are ____-___ ____, which test for neural-tube defects and ______ which shows chromosomal abnormalities and other genetic and prenatal problems.
Although pediatrics AIDS has almost dissapeared from ______ ____ and ____, it is still on the rise in _______.
North america; europe; africa
Most fetuses _____ during the last month of prenancy. About 1 in 20 babies is born "_____", with buttocks or rarely feet first. Worse is a ______ ______ in which the fetus turns sideways.
change; breech; transverse lie
About ____ weeks after conception the fetal brain signals the release of certain _____ into the mothers bloodstream, which triggers her _____ ______ to contract and relax. The normal birth process begins when these contractions become regular. The average length of labor is _____ hours for first births and ____ hours for subsequent births.
38;hormones; uterine muscle; 12;7
In developed nations the newborn is usually rated on the _____ ______, which assigns a score of either 0,1,2 to each of the following five characteristics __________________. A score below _______ indicates that the newborn is in critical condition and requires immediate attention ; if the score is ____ or better all is well. This rating is made twice, at _____ minute after birth and again at _____ min.
apgar scale; heart rate, breathing, skin tone, muscle tone, and reflexes; 4; 7; one; five
The birth experience is influenced by several factors, including ____ ______.
parents preparation for birth, the physical and emotional support, posotion and size of fetus, the customs of culture.
In about 31 percent of U.S births a surgical procedure called a _____ _____ is performed.
A growing number of north american mothers today use a professional birth coach, or _______ to assist them.
The disorder ___ ____, which affects motor centers in the brain often results from ______ vulnurability, worsened by exposure to _____ and a pattern birth that involves ____, a temporary lack of ______ during birth.
cerebral pulsy; genetic; teratogans; anoxia; oxygen
Babies who are born 3 or more weeks before the standard 38 weeks have elapsed are called ______.
Infants who weigh substancely less then they should given how much time has passed since conception are called ___ ___ ____ ____.
small for gestational age.
Cause SGA include problems with the ____ or ______ ____, as well as maternal illness. However maternal _____ use is a more common reason. About 25 percent of all LBW births are linked to maternal use of ______. prescription drugs can also cause low birthweight.
placenta; umbilical cord; drug; tabacco