In human prenatal developmentfetal development begins from the ninth week after fertilisation or eleventh The Fetals* - Fetalmania gestational age and continues until birth.
However, a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final anatomical location. The British, Irish, and Commonwealth spelling is foetusThe Fetals* - Fetalmania has been in use since at least This spelling is the most common in most Commonwealth nationsexcept in the medical literature, where fetus is used.
The more classical spelling fetus is used in Canada and the United States. In addition, fetus is now the standard English spelling throughout the world in medical journals. In humans, the fetal stage commences at the beginning of the ninth week,  fertilisation age or eleventh week gestational age. At the start of the fetal stage, the fetus is typically about 30 millimetres 1. At this point in development, uncontrolled movements and twitches occur as muscles, the brain, and pathways begin to develop.
A woman The Fetals* - Fetalmania for the first time nulliparous typically feels fetal movements at about 21 weeks, whereas a woman who has given birth before will typically feel movements by 20 weeks. The amount of body fat rapidly increases. Lungs are not fully mature. Thalamic brain connections, which mediate sensory input, form. Bones are The Fetals* - Fetalmania developed, but are The Fetals* - Fetalmania soft and pliable.
Ironcalciumand phosphorus The Fetals* - Fetalmania more abundant. Fingernails reach the end of the fingertips. The lanugoor fine hair, begins to disappear, until it is gone except on the upper arms and shoulders.
Small breast buds are present on both sexes. Head hair becomes coarse and thicker. Birth is imminent and occurs around the 38th week after fertilization. The fetus is considered full-term between weeks 36 and 40, when it is sufficiently developed for life outside the uterus. Control of movement is limited at birth, and purposeful voluntary movements develop all the way until puberty.
There is much variation in the growth of the human fetus. When fetal size is less than expected, the condition is known as intrauterine growth restriction IUGR also called fetal growth restriction FGR ; factors affecting fetal growth can be maternalplacentalor fetal. Maternal factors include maternal weightbody mass indexnutritional state, emotional stresstoxin exposure including tobaccoalcoholheroinand other drugs which can also harm the fetus in other waysand uterine blood flow.
Placental factors include size, microstructure densities and architectureumbilical blood flow, transporters and binding proteins, nutrient utilization and nutrient production. Fetal factors include the fetus genome, nutrient production, and hormone output. Also, female fetuses tend to weigh less than males, at full term. Low birth weight increases risk for perinatal mortality death shortly after birthasphyxiahypothermiapolycythemiahypocalcemiaimmune dysfunctionNostalgic Violins - Various - The String Family abnormalities, and other long-term health problems.
SGA may be associated with growth delay, or it may instead be associated with absolute stunting of growth. Fetal viability refers to a point in fetal development at which the fetus may survive outside the womb. There is no sharp limit of development, age, or weight at which a fetus automatically becomes viable. When such premature babies are born, The Fetals* - Fetalmania main causes of mortality are that the respiratory system and the central nervous system are not completely differentiated.
If given expert postnatal care, some preterm babies weighing less The Fetals* - Fetalmania 1. Preterm birth is the most common cause of infant mortality, causing almost 30 percent of neonatal deaths. The heart and The Fetals* - Fetalmania vessels of the circulatory systemform relatively early during embryonic developmentbut continue to grow and develop in complexity in the growing fetus.
A functional circulatory system is a biological necessity, since mammalian tissues can not grow more than a few cell layers thick without an active blood supply. The prenatal circulation of blood is different from postnatal circulation, mainly because the lungs are not in use. The fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord. Blood from the placenta is carried to the fetus by the umbilical vein.
About half of this enters the fetal ductus venosus and is carried The Velvet Underground - The Velvet Underground & Nico the inferior vena cavawhile the other half enters the liver proper from the inferior Snagda - Vervamon - The Path Through The Ever Green Forest (A Collection Of Music From 1999 To 2005) of the liver.
The branch of the umbilical vein that supplies the right lobe of the liver first joins with the portal vein. The blood then moves to the right atrium of the heart. In the fetus, there is an opening between the right and Miles Davis - Jean Pierre atrium the foramen ovaleand most of the blood flows from the right into the left atrium, thus bypassing pulmonary circulation.
The majority of blood flow is into the left ventricle from where it is pumped through the aorta into the body. Some of the blood moves from the aorta through the internal iliac arteries to the umbilical arteries, and re-enters the placenta, where carbon dioxide and other waste products from the fetus are taken up and enter the woman's circulation.
Some of the blood from the right atrium does not enter the left atrium, but enters the right ventricle and is pumped into the pulmonary artery. In the fetus, there is a special connection between the pulmonary artery and the aorta, called the ductus arteriosuswhich directs most of this blood away from The Fetals* - Fetalmania lungs which aren't being used for respiration at this point as the fetus is suspended in amniotic fluid. With the first breath after birth, the system changes suddenly.
Pulmonary resistance is reduced dramatically, prompting more blood to move into the pulmonary arteries from the right atrium and ventricle of the heart and less to flow through the foramen ovale into the left atrium. The blood from the lungs travels through the pulmonary veins to the left atrium, producing an increase in pressure that pushes the septum primum against the septum secundumclosing the foramen ovale and completing the separation of the newborn's circulatory system into the standard left and right sides.
Thereafter, the foramen ovale is known as the fossa ovalis. The ductus arteriosus normally closes within one or two days of birth, leaving the ligamentum arteriosumwhile the umbilical vein and ductus venosus usually closes within two to five days after birth, leaving, respectively, the liver's ligamentum teres and ligamentum venosus. The placenta functions as a maternal-fetal barrier against the transmission of microbes.
When this is insufficient, mother-to-child transmission of infectious diseases can occur. Maternal IgG antibodies cross the placenta, giving the fetus passive immunity against those diseases for which the mother has antibodies.
This transfer of antibodies in humans begins as The Fetals* - Fetalmania as the fifth month gestational age and certainly by the sixth month. A developing fetus is highly susceptible to anomalies in its growth and metabolism, increasing the risk of birth defects.
One area of concern is the lifestyle choices made during pregnancy. Studies show that supplementation of the person's diet with folic acid reduces the risk of spina bifida and other neural tube defects. Another dietary concern is whether breakfast is eaten. Skipping breakfast could lead to extended periods of lower than normal nutrients in the maternal blood, leading to a higher risk of prematurityor birth defects.
Alcohol consumption may increase the risk of the development of fetal alcohol syndromea condition leading to intellectual disability in some infants.
Low birth weight is a concern for medical providers due to the tendency of these infants, described as " premature by weight", to have a higher risk of secondary medical problems. X-rays are known to have possible adverse effects on the development of the fetus, and the risks need to be weighed against the benefits. A particular concern is the possible link between The Fetals* - Fetalmania widespread use of fetal ultrasounds over the years, and the huge increase in the numbers of autism cases.
Congenital disorders are acquired before birth. Infants with certain congenital heart defects can survive only as long The Fetals* - Fetalmania the ductus remains open: in such cases the closure of the ductus can be delayed by the administration of prostaglandins to permit sufficient time for the surgical correction of the anomalies.
Conversely, in cases of patent ductus arteriosuswhere the ductus does not Weaponized - Wolf Parade - Cry Cry Cry (Vinyl, LP, LP, Album) close, drugs that inhibit prostaglandin synthesis can be used to encourage its closure, so that surgery can be avoided.
Other heart birth defects include ventricular septal defectpulmonary atresiaand tetralogy of Fallot. An abdominal pregnancy can result in the death of the fetus and where this is rarely not resolved it can lead to its formation into a lithopedion.
Fetal pain its existence and its implications are debated politically and academically. According to the conclusions of a review published in"Evidence regarding the capacity for fetal pain is limited but indicates that fetal perception of pain is unlikely before the third trimester. Whether a fetus has the ability to feel pain and suffering is part of the abortion debate. A fetus is a stage in the prenatal development of viviparous organisms.
This stage lies between embryogenesis and birth . Many vertebrates have fetal stages, ranging from most mammals to many fish. In addition, some invertebrates bear live young, including some species of onychophora  and many arthropods. The prevalence of convergent evolution to the fetal stage shows that it is relatively easy to Hartfords Coffin - Boud Deun - A General Observation. It presumably originates from a delay of egg release, with the The Fetals* - Fetalmania being hatched inside the parent before being laid.
Over time, the robustness of the egg wall can be decreased until it becomes little more than a sac. The fetuses of most mammals are situated similarly to the human fetus within their mothers. Development at birth varies considerably among animals, and even among mammals.
Altricial species are relatively helpless at birth and require considerable parental care and protection. In contrast, precocial animals are born with open eyes, have hair or down, have large brains, and are immediately mobile and somewhat able to flee from, or defend themselves against, predators. Primates are precocial at birth, with the exception of The Fetals* - Fetalmania . The duration of gestation in placental mammals varies from 18 days in jumping mice to 23 months in elephants.
The benefits of a fetal stage The Fetals* - Fetalmania that young are more developed when they are born. Therefore, they may need less parental care and may be better able to fend for themselves. However, carrying fetuses exerts costs on the mother, who must take on extra food to fuel the growth of her offspring, and whose mobility and comfort may be affected especially toward the end of the fetal stage.
In some instances, the presence of a fetal stage may allow organisms to time the birth of their offspring to a favorable season. From Wikipedia, the free encyclopedia. This article is about the stage of prenatal development. For other uses, see Fetus disambiguation. For the band, see Foetus band. For the film, see Foetus film. Developmental stage theories. Further information: Prenatal development. Further information: Birth weight and Environmental toxicants and fetal development.
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