Exam 18: Development Throughout Life

________ is the primary germ layer that forms the nervous system and the outer layer of skin and its derivatives such as hair,nails,oil glands,sweat glands,and mammary glands.

Why do harmful agents cause the most severe birth defects during the embryonic period?

________ are blocks of mesoderm that eventually form skeletal muscles of the neck and trunk,connective tissue,and vertebrae.

Sometimes splitting of the pre-embryo is incomplete during the development of twins and ________ twins result.

The ________ is an extraembryonic membrane that surrounds the embryo and serves to protect and cushion the embryo.

Suppose someone told you that the activities of a pregnant female have no effect on the embryo during early embryonic development because the placenta is not fully formed until later.How would you respond to this statement?

The blastocyst attaches to the ________ about 6 days after fertilization and begins to digest its way inward.

Match each definition in the first column to the correct term in the second column. -Increases its size after it frees itself from the zona pellucida.

Which is the temporary vessel that shunts most blood past the fetal liver?

Which of the following maintains the corpus luteum and stimulates it to continue to produce the hormone progesterone?

Certain medications that have major medical benefits can have tragic consequences when taken by a pregnant woman; for example,the drug thalidomide and the acne drug Acutane,which are both available only by prescription in this country.When a drug such as Acutane is prescribed to a female,she is also educated on the risks of becoming pregnant while on the drug and is prescribed a method of hormonal birth control to ensure that pregnancy does not occur.Suppose a woman taking this drug did manage to become pregnant.How much responsibility should be with the drug makers and physician who prescribed the medication? Should these drugs be available at all?

In fetal circulation,most blood is shunted away from the lungs.Why is this the case?

Match each definition in the first column to the correct term in the second column. -Process during which a single sperm penetrates the secondary oocyte,which will eventually result in the fusion of the egg and sperm nuclei and the development of a zygote.

Developmental problems present at birth are known as ________.

The development of organ systems in the embryo is prioritized based on when the system is needed.One of the first organ systems to develop in the embryo is the ________ system,while one of the last systems to develop is the ________ system.

Once the fertilized ovum has divided into two cells it is called the ________.

Match each definition in the first column to the correct term in the second column. -Orchestrates all interactions between the mother and the embryo and later fetus.

Labor is directly triggered by the hormone ________ which also triggers ________ after birth.

Match each definition in the first column to the correct term in the second column. -The fertilized ovum that contains genetic material from both parents for a total of 46 chromosomes.

It is possible for an individual to be genotypically one gender but phenotypically the opposite gender.Suppose an individual is genotypically male (XY)but has developed as a female.Explain what has happened and when it might have happened.