Question 1

Which of the following organ systems is functional by the end of the 4th embryonic week?&#10;A) Cardiovascular&#10;B) Respiratory&#10;C) Musculoskeletal&#10;D) Urogenital

Accepted Answer

The cardiovascular system is the first functional system to develop and begins to form in the third week of embryonic development, with a functional heart beginning to beat by the end of week 4. The respiratory, musculoskeletal, and urogenital systems all develop later in embryonic development.

Question 2

Which of the following sensory systems is LEAST developed in the fetus?&#10;A) Touch&#10;B) Vision&#10;C) Vestibular&#10;D) Hearing

Accepted Answer

Vision is the sensory system that is least developed in the fetus. The fetus has eyelids fused shut and lacks the ability to focus on objects outside of the womb. In contrast, by the third trimester, the fetus has well-developed touch, vestibular, and hearing capabilities.

Question 3

An embryo is MOST susceptible to teratogens affecting the developing limbs during the ________________ weeks:&#10;A) 1st to 2nd&#10;B) 9th to 12th&#10;C) 4th to 7th&#10;D) None of these

Accepted Answer

During the 4th to 7th weeks of gestation, the embryonic period occurs, and organogenesis takes place. This is the time when the formation of the limbs occurs, and they are particularly susceptible to teratogenic effects, which can result in limb abnormalities.

Question 4

The embryonic period is characterized by all of the following statements EXCEPT:&#10;A) It lasts from the end of germinal stage through 8 weeks.&#10;B) It is a period of major susceptibility to teratogens.&#10;C) It represents the period before placental circulation is established.&#10;D) It is the period when most body structures form and early functions begin.

Accepted Answer

Placental circulation is established during the embryonic period, so statement C is incorrect. A, B, and D are all true statements about the embryonic period.

Question 5

The minimal age of fetal viability is:&#10;A) 8 to 10 weeks&#10;B) 22 to 24 weeks&#10;C) 32 to 34 weeks&#10;D) 38 to 42 weeks

Accepted Answer

The minimal age of fetal viability, meaning the earliest gestational age at which a fetus can survive outside the womb with medical intervention, is currently considered to be between 22 and 24 weeks. This is based on advancements in medical technology, particularly in neonatal intensive care units, which have improved survival rates for premature babies born at this gestational age. It's important to note that viability is still dependent on individual factors such as the health of the mother and fetus, and that not all babies born at this stage will survive or avoid long-term health complications.

Question 6

The neural tube forms from:&#10;A) Neurectoderm&#10;B) Mesoderm&#10;C) Neuroendoderm&#10;D) Notochord

Accepted Answer

The neural tube is formed from the neurectoderm, which is a layer of cells that differentiates from the ectoderm during embryonic development. The neurectoderm eventually forms the brain and spinal cord. The mesoderm gives rise to muscle, bone, and connective tissue, while the neuroendoderm refers to the endoderm-derived cells that are involved in neural development. The notochord, while important in embryonic development, does not directly contribute to the formation of the neural tube.

Question 7

The neural tube completes closure in which week after conception?&#10;A) 2nd&#10;B) 4th&#10;C) 8th&#10;D) 12th

Accepted Answer

The neural tube completes closure in the 4th week after conception, which is a critical stage in early embryonic development. This closure forms the beginning of the brain and spinal cord. If this process is disrupted or incomplete, it can lead to neural tube defects affecting the spine and brain, such as spina bifida or anencephaly.

Question 8

Which of the following is true about gestational age dating of the pregnancy?&#10;A) It is an exact date by Carnegie classification.&#10;B) It is 2 weeks older than the embryo actually is from conception.&#10;C) It is 2 weeks younger than the embryo actually is from conception.&#10;D) It is equivalent to the embryonic age from time of conception.

Accepted Answer

Gestational age dating of a pregnancy is typically 2 weeks older than the actual embryonic age from the time of conception. This is because gestational age is calculated from the first day of the last menstrual period (LMP), not from the date of conception, which usually occurs about 2 weeks later.

Question 9

Which of the following structures is the immediate precursor to the fetal membranes and placenta?&#10;A) Inner cell mass&#10;B) Epiblast&#10;C) Trophoblast&#10;D) Morula

Accepted Answer

The trophoblast is the outermost layer of cells that develops around the blastocyst and will eventually give rise to the fetal membranes and placenta. The inner cell mass (A) will develop into the embryo itself, while the epiblast (B) contributes to the formation of the amniotic cavity. The morula (D) is an early stage of embryonic development before the blastocyst forms.

Question 10

Which of the following tissues does NOT develop from mesoderm?&#10;A) Spinal cord&#10;B) Muscle&#10;C) Heart&#10;D) Bone

Accepted Answer

The spinal cord develops from the ectoderm, specifically the neural plate. Muscle, heart, and bone all develop from mesoderm.

Deck 8: Prenatal Development