Question

Your textbook describes three different periods of prenatal development, pages 76 - 80. List the stages of each period.

What are the characteristics of Fetal Alcohol Syndrome? How much alcohol can a pregnant woman safely consume? Is alcohol considered a teratogen?

How does a physician attending a woman in labor know how much of a drug should be used?

Sarah has just arrived. On the Apgar her heart rate is 1, her respiratory effort is 1, muscle tone is 5, body color is 0 and reflex irritability is 1. What does her score indicate?

Life Span & Developmental Growth!

Answer 1

• Development happens quickly during the Prenatal Period, which is the time between conception and birth. This period is generally divided into three stages: the germinal stage, the embryonic stage, and the fetal stage.
• Germinal Period:- Conception typically occurs at what is considered the 2nd week of pregnancy.Conception is also the beginning of the germinal period of prenatal development. This stage occurs during the first 2 weeks of development (or the 2nd - 4th weeks of pregnancy).
• The union of the sperm and egg cell forms a single cell called a zygote. The zygote moves along the Fallopian tube toward the uterus. At the same time, the zygote is rapidly dividing in a process called cleavage.
• Once it reaches the uterus, the zygote becomes what is called a blastocyst, and it begins to implant into the wall of the uterus. The germinal period ends when the blastocyst is fully implanted into uterine tissue.
• Embryonic Period-This stage lasts from implantation until about 8 weeks from the time of conception (or the 10th week of pregnancy). 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. One of the first examples of this is a division between the cells that will make up the placenta and the cells that will make up the baby.
• After this, a process called gastrulation forms three layers called germ layers. The outer layer is called the ectoderm, the middle layer is called the mesoderm, and the inner layer is called the endoderm.
• Each germ layer will differentiate into different structures. The ectoderm will form many outer tissues such as skin and hair, as well as most of the nervous system tissues - including the brain.
• The mesoderm will form tissues inside the body such as the lungs, bones, and muscles - including the heart. The endoderm will form tissues such as the digestive tract and bladder, as well as other internal organs.
• All of the essential structures have been formed (both inside and outside) by the time the embryonic period comes to an end. The new title of fetus is now given to the embryo.
• Embryogenesis is a term that can be used to describe all of the processes of embryo development up until the time it becomes a fetus.
• Fetal Period:-This final stage of development is called the fetal period of development. This stage takes place from the end of the embryonic period until the time of birth (or the 10th to 40th weeks of pregnancy).
• About one month into this stage, the sex organs of the fetus begin to form. The fetus quickly grows as bones and muscles form, and it begins to move inside the uterus. Organ systems develop further and start to function.
• During the last three months, the brain increases rapidly in size, an insulating layer of fat forms under the skin, and the respiratory and digestive systems start to work independently.
• Alcohol is the most common teratogen affecting humans. It is rated as the most common non-genetic cause of mental and behavioural problems in children.
• Fetal alcohol syndrome is a condition in a child that results from alcohol exposure during the mother's pregnancy. Fetal alcohol syndrome causes brain damage and growth problems. The problems caused by fetal alcohol syndrome vary from child to child, but defects caused by fetal alcohol syndrome are not reversible.
• The sole risk factor for Fetal Alcohol Syndrome(FAS) is maternal consumption of alcohol during pregnancy. Alcohol is a teratogenic substance which crosses the placenta with ease. Development of the fetus can be affected by alcohol at any stage. Different effects may occur depending on the stage of exposure, however.
• Not all women who drink heavily during pregnancy have babies with FAS and it is clear that other factors affect the vulnerability of the fetus. These include the stage of pregnancy affected, the pattern of drinking, the health, age, stress levels and nutritional status of the mother and the use of other toxic substances, including tobacco.
• Genetic makeup and gene polymorphisms also strongly affect fetal vulnerability for FAS, and other genetic abnormalities can be confused with FAS.
• Signs and symptoms of fetal alcohol syndrome may include any mix of physical defects, intellectual or cognitive disabilities, and problems functioning and coping with daily life.
• There is no amount of alcohol that's known to be safe to consume during pregnancy. If a woman may drink during pregnancy, she does places her baby at risk of fetal alcohol syndrome.
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