When serious defects occur during the embryonic period they often

In general, major defects of the body and internal organs are more likely to occur between 3 to 12 embryo / fetal weeks. This is the same as 5 to 14 gestational weeks (weeks since the first day of your last period). This is also referred to as the first trimester.

What happens when serious defects occur during the embryonic period?

Genetic and Environmental Risks to Embryonic Development Genetic defects or harmful environmental exposures during this stage are likely to have devastating effects on the developing organism. They may cause the embryo to die and be spontaneously aborted (also called a miscarriage).

When serious defects occur during the embryonic period often result in ?

Serious defects during the embryonic stage can lead to a miscarriage, or to complicated birth defects. Depending on which group of cells is affected…

When serious defects occur during the embryonic period they often quizlet?

Serious defects that emerge during the embryonic period often cause a miscarriage, or spontaneous abortion. The fetal period is marked by the appearance of bone. 17 to 20 weeks, the mother can feel the fetus move. The skin is covered vernix caseosa, which protects the fetal skin.

What occurs during the embryonic period?

The embryonic stage of gestation is the period after implantation, during which all of the major organs and structures within the growing mammal are formed. Once the embryo is fully formed, it expands, grows, and continues to develop in what is known as the fetal development stage.

What can cause developmental abnormalities in the developing embryo and fetus?

Most early embryonic and fetal demise is probably due to chromosomal abnormalities that interfere with normal developmental processes. Abnormalities caused by exogenous agents (certain chemicals or viruses, radiation, or hyperthermia) are called disruptions.

What are the causes of developmental disabilities in embryonic stage?

Common causes of developmental disabilities include genetic or chromosomal abnormalities, substance exposure, preterm birth, low birth weight and specific infectious diseases.

Why is the embryo particularly susceptible to damage from teratogens?

The embryo is most susceptible to teratogenic agents during periods of rapid differentiation. The stage of development of the embryo determines suscep- tibility to teratogens. The most critical period in the development of an embryo or in the growth of a particular organ is during the time of most rapid cell division.

During which prenatal period is the developing organism most at risk for developing a birth defect?

The first trimester of pregnancy is defined as up to the 14th week of pregnancy (13 weeks and 6 days) counting since the first day of your last menstrual period. Harmful exposures during the first trimester have the greatest chance of causing major birth defects.

During which prenatal stage of development is the organism most susceptible to major structural abnormalities quizlet?

As in the case of the germinal period, often the mother does not yet know that she is pregnant. It is during this stage that the major structures of the body are taking form making the embryonic period the time when the organism is most vulnerable to the greatest amount of damage if exposed to harmful substances.

Article first time published on

During which stage of fetal development is exposure to teratogens most damaging quizlet?

Why does the timing of teratogenic exposure matter? – The effects of a teratogenic agent are worst during the critical period when an organ system grows most rapidly. – Organogenesis takes place during the embryonic period (weeks 3-8 of prenatal development).

Why the embryonic period was regarded as the most dramatic prenatal period?

The embryonic period is the most critical period of development because of the formation of internal and external structures. The critical periods of development for the organs are also discussed in the section on specific organ development.

What are the 4 stages of embryonic development?

• 1.1 Fertilization.
• 1.2 Cleavage.
• 1.3 Blastulation.
• 1.4 Implantation.
• 1.5 Embryonic disc.

Which actions supports healthy fetal development?

Eat nutrient-dense meals. Gain as little weight as possible. Attend regular prenatal checkups. Avoid moderate physical activities.

What are pregnancy complications?

• High blood pressure. High blood pressure occurs when the arteries that carry blood from the heart to the organs and the placenta are narrowed. …
• Gestational diabetes. …
• Preeclampsia. …
• Preterm labor. …
• Miscarriage. …
• Anemia. …
• Infections. …
• Breech position.

Which of the following occurs during the embryonic period of prenatal development?

The Embryonic Period This period begins once the organism is implanted in the uterine wall. It lasts from the third through the eighth week after conception. During this period, cells continue to differentiate and at 22 days after conception the neural tube forms which will become the brain and spinal column.

What causes abnormalities in baby during pregnancy?

What causes birth defects? Some birth defects are caused by genes that can be passed from parents to children. Others result from a problem with chromosomes. A small number of birth defects are caused by exposure during pregnancy to certain medications, infections, and chemicals.

What are some abnormalities that can be developed during the prenatal period?

Maternal Disease: A number of maternal diseases can negatively impact the fetus, including herpes, rubella, and AIDS. Herpes virus is one of the most common maternal diseases and can be transmitted to the fetus, leading to deafness, brain swelling, or intellectual disability.

What influences cause developmental disabilities?

These factors include genetics; parental health and behaviors (such as smoking and drinking) during pregnancy; complications during birth; infections the mother might have during pregnancy or the baby might have very early in life; and exposure of the mother or child to high levels of environmental toxins, such as lead …

What are developmental abnormalities?

A developmental anomaly is a broad term used to define conditions which are present at conception or occur before the end of pregnancy. In the case of cerebral palsy, a small number also occur after birth. An anomaly is considered as a departure from normal development.

What are the 4 main causes of birth defects?

• Genetics. One or more genes might have a change or mutation that prevents them from working properly. …
• Chromosomal problems. …
• Exposures to medicines, chemicals, or other toxic substances. …
• Infections during pregnancy. …
• Lack of certain nutrients.

What is the most common birth defect?

There are thousands of different birth defects. The most common are heart defects, cleft lip and palate, Down syndrome and spina bifida.

When is the most serious damage from teratogens likely to occur?

The timing of the exposure: Structures in the body are vulnerable to the most severe damage when they are forming. If a substance is introduced during a particular structure’s critical period (time of development), the damage to that structure may be greater.

What is the critical period during pregnancy?

The first trimester is the most crucial to your baby’s development. During this period, your baby’s body structure and organ systems develop. Most miscarriages and birth defects occur during this period.

Why is the embryonic stage considered the most critical stage of prenatal development?

This is the most important time of prenatal development because the embryo is developing the foundations for a healthy baby. The blastocyst that implanted in the uterus continues to divide rapidly after implantation. Through a process called differentiation, cells begin to take on different functions.

What birth defects are caused by teratogens?

During this time, teratogens can cause neural tube defects such as spina bifida. Some organs are sensitive to teratogens during the whole pregnancy. This includes the baby’s brain and spinal cord. Alcohol affects the brain and spinal cord, so it can cause harm at any time during pregnancy.

Which teratogen is the leading cause of developmental disabilities?

Alcohol use (beer, wine, or hard liquor) during pregnancy is the leading cause of preventable birth defects and intellectual disabilities in the United States. Fetal alcohol syndrome and other FASDs can be prevented by not drinking any alcohol during pregnancy.

Which disorder caused by teratogens is the leading cause of birth defects?

How can fetal alcohol syndrome (FAS) be prevented? Using alcohol during pregnancy is the leading cause of preventable birth defects, developmental disabilities, and learning disabilities.

What is the period of prenatal development where the most harm from teratogens usually occurs quizlet?

If a teratogen has the potential to interfere with the closure of the neural tube, for example, the exposure to the teratogen must occur in the first 3.5 to 4.5 weeks of the pregnancy, since this is when the neural tube is closing.

Which of the following occurs during the embryonic stage of development quizlet?

Which of the following occurs during the embryonic stage of development? Nose, eyes, and ear become noticeable.

Why do teratogens often do the most damage during the embryonic period quizlet?

Teratogens do more damage when they occur at some points in development than at others. Damage during the germinal period may even prevent implantation. In general, the embryonic period is more vulnerable than the fetal period.