The Role of Genes in Prenatal Development Prenatal development is highly influenced by the inheritance, expression, and regulation of genes.
Germinal stage definition
Prenatal Development Developmental psychologists consider the process of human development as it relates to physical, cognitive, and psychosocial development. A study further investigated neurocognitive and neurodevelopmental effects of prenatal methamphetamine exposure. Eyes, nose, digestive system and even the first stage of toe formation can be seen. Now blood vessels grow, forming the placenta. Once these neurons have formed, they begin to migrate to their correct locations. Perhaps most noticeably, the fetus increases quite dramatically in size, increasing about six times in size. DES-exposed fetuses have been shown to have higher rates of cancer and infertility as adults. The embryo begins to divide into three layers each of which will become an important body system. Explain how the developing embryo and fetus may be harmed by the presence of teratogens and describe what a mother can do to reduce her risk. The embryonic stage focuses on the embryo, which is a developing human organism between about the third and the eighth week after conception. The screenings detect potential birth defects, including neural tube defects, chromosomal abnormalities such as Down syndrome , genetic diseases, and other potentially dangerous conditions. As neurons form, they migrate to different areas of the brain.
This period consists of the fetus gaining approximately 7 pounds more than 3, grams and the organs continuing to develop, slowly gaining the ability to function independently. Learning Objectives Explain the importance of genetics in prenatal development Key Takeaways Key Points Prenatal development is the process that occurs during the 40 weeks prior to the birth of a child, and is heavily influenced by genetics.
Methamphetamine[ edit ] Prenatal methamphetamine exposure has shown to negatively impact brain development and behavioral functioning. The head develops in the fourth week and the precursor to the heart begins to pulse. References Berk, L. Examples of diseases include chlamydia, syphilis, tuberculosis, malaria, and toxoplasmosis. The fetus moves with more coordination, indicating more neural connections within the brain. Therefore, the best approach for expectant mothers is to avoid alcohol completely. During the embryonic phase, which will last for the next six weeks, the major internal and external organs are formed, each beginning at the microscopic level, with only a few cells. Prenatal depression is often caused by the stress and worry that pregnancy can bring, only at a more severe level. Figure 7. The cerebral cortex grows larger, and the fetus spends more hours awake. By the time some 30 blastomeres have been produced, pools of clear fluid accumulate between some of the internal cells, and these spaces soon coalesce into a common subcentral cavity. Sonographic markers of fetal a-thalassemia major.
This is the longest stage, starting in the ninth week after conception and continuing until birth. Determining the extent to which adverse outcomes are caused by antidepressant use or by depression—or a combination of both—is difficult to measure; it is also important to factor in the negative consequences of a mother going off prescription antidepressants during pregnancy, which may adversely effect her health in other ways.
Once they have reached the correct location, they begin to form connections with other neural cells, establishing rudimentary neural networks. Key Terms zygote: A fertilized egg cell.
Three-dimensional ultrasound of the fetus: How does it help? By the time some 30 blastomeres have been produced, pools of clear fluid accumulate between some of the internal cells, and these spaces soon coalesce into a common subcentral cavity.
The germinal stage occurs from conception until 2 weeks implantationduring which the zygote begins to rapidly divide. At the end of the embryonic period, the embryo is only about an inch long.
Given the negative effects of poverty on human development, what steps do you think societies should take to try to reduce poverty? For this reason, genetics play a particularly important role in prenatal development.
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