105 Questions
Which structure carries oxygen and nutrients acquired from the mother’s intervillous spaces into the fetus?
Umbilical vein
What is the process called when the embryo is converted from a flat, two-dimensional trilaminar embryonic disc to a three-dimensional cylinder?
Embryonic folding
Which part of the embryo undergoes rapid longitudinal growth and is mainly responsible for embryonic folding?
Nervous system (neural tube)
Which body system begins to develop by the end of the eighth week of embryonic development?
Digestive system
During the fifth week of development, which part of the body shows considerable growth due to rapid brain development?
Head
At what point does the upper limb development begin in the embryo?
Around the middle of the fourth week
What is formed on each side of the future head and neck regions during the fourth week?
Pharyngeal arches
Which structure appears around 22 days after fertilization and is a sign of developing ear in the embryo?
Otic placode
When do the beginnings of digits appear in the limbs?
Seventh week
What percentage of total body mass is body fat in a fetus with visible toenails?
8%
During which period does the fetus experience a remarkable rate of body growth, especially in the second half?
Fetal period
At what stage can the heartbeat of the fetus be detected?
Sixth week
During which stage do external ears develop and become low set on the fetus?
Fetal period
At what percentage of total body mass does body fat reach its peak before birth?
16%
Which of the following statements about fetal development is true?
Fetal movements are commonly felt by the mother after the 20th week.
In which part of the fetal body does skin appear pink and wrinkled as birth approaches?
Abdomen
What happens to the growth rate as birth approaches?
Growth rate decelerates
Which of the following statements about the placenta is incorrect?
It begins to form during the 4th week of development.
By the beginning of the twelfth week, the placenta has two distinct parts. Which of the following correctly identifies these parts?
The fetal portion develops from the chorion, and the maternal portion forms from the endometrium of the uterus.
What is the primary function of the placenta?
To allow oxygen and nutrients to diffuse from maternal blood into fetal blood, and carbon dioxide and wastes to diffuse in the opposite direction.
Which of the following statements about the placenta is correct?
Certain viruses, such as those that cause AIDS, German measles, chickenpox, measles, encephalitis, and poliomyelitis, can cross the placenta.
What happens during the exchange of nutrients and wastes between the mother and embryo/fetus?
Oxygen and nutrients in the blood of the mother's intervillous spaces diffuse across the cell membranes into the capillaries of the villi, while waste products such as carbon dioxide diffuse in the opposite direction.
Which of the following substances can pass freely through the placenta?
Both alcohol and drugs, and substances that can cause birth defects
At what stage of development does the placenta begin to form?
During the 2nd week of development
Which of the following statements about the maternal and embryonic blood vessels in the placenta is correct?
The maternal and embryonic blood vessels are completely separate, and the blood they carry does not mix.
What gives the umbilical cord its shiny appearance?
Amnion
During embryonic folding, what is the main force responsible for the process?
Rapid longitudinal growth of the nervous system
What differentiates into an anterior foregut, an intermediate midgut, and a posterior hindgut during embryonic development?
Primitive gut
What structures begin their development on the 22nd day after fertilization and form swellings on the surface of the embryo?
Pharyngeal arches
What appears at 22 days after fertilization as a sign of developing ear in the embryo?
Otic placode
During which week of development does a very rapid development of the brain occur?
Fifth week
What begins their development as outgrowths of mesoderm covered by ectoderm called upper limb buds?
Upper limbs
Which part brings the developing heart and mouth into their eventual adult positions as a result of embryonic folding?
Head fold
At what stage does the fetal head size transition from being half the length of the body to only one-quarter the length of the body?
During the fetal period
According to the information provided, during which period do the limbs increase in size from one-eighth to one-half the fetal length?
Fetal period
Which of the following statements accurately describes the development of the fetus during the fetal period?
Very few new structures appear, but the rate of body growth is remarkable
At what stage does the fetus begin to move, although the movements cannot be felt by the mother?
At the beginning of the fetal period
Which of the following statements accurately describes the development of the fetus during the fetal period?
The lower limbs lengthen, and the eyes move medially to their final positions
According to the information provided, which of the following statements is true about the development of the fetus during the fetal period?
The head becomes more proportionate to the rest of the body
During which stage of fetal development does the fetus assume an upside-down position?
During the late fetal period, around 38 weeks
According to the information provided, what percentage of total body mass is body fat in a full-term fetus?
16%
Which of the following statements is true about the development of the fetus during the fetal period?
The testes descend toward the scrotum during the late fetal period, between 28 and 32 weeks
Which of the following best describes the function of the placenta?
It facilitates the exchange of oxygen, nutrients, and waste products between the mother and fetus while acting as a protective barrier against most microorganisms.
What is unique about the development of the placenta?
It develops from two separate individuals, the mother and the embryo, with distinct maternal and fetal portions.
Which of the following substances can cross the placental barrier and potentially harm the developing fetus?
Certain viruses, drugs, alcohol, and teratogenic substances
At what stage of development does the placenta begin to form?
During the second week of development
Which statement accurately describes the relationship between maternal and embryonic blood vessels in the placenta?
The maternal and embryonic blood vessels remain separate, with oxygen and nutrients diffusing across cell membranes.
By the beginning of the twelfth week, which of the following correctly identifies the two distinct parts of the placenta?
The maternal portion develops from the endometrium, and the fetal portion develops from the chorion.
Which of the following statements about the exchange of nutrients and wastes between the mother and embryo/fetus is correct?
Oxygen and nutrients diffuse from maternal blood into fetal blood, while carbon dioxide and wastes diffuse from fetal blood into maternal blood.
Which of the following statements best describes the protective function of the placenta?
The placenta acts as a selective barrier, preventing most microorganisms from passing through but allowing certain viruses to cross.
The placenta is the site where carbon dioxide and wastes diffuse from maternal blood into fetal blood.
False
The placenta develops solely from the mother's reproductive organs.
False
The maternal and embryonic blood vessels in the placenta join and their blood mixes freely.
False
The placenta is permeable to all microorganisms, allowing them to pass through freely.
False
Certain viruses such as AIDS can cross the placenta and affect the developing fetus.
True
Alcohol, drugs, and substances that can cause birth defects cannot pass through the placenta.
False
The fetal portion of the placenta develops from the endometrium of the uterus.
False
Nutrients and oxygen diffuse from fetal blood into maternal blood through the placenta.
False
The placenta begins to form during the 1st week of development.
False
The placenta does not play a role in sustaining the pregnancy by producing essential hormones.
False
During the fetal period, new structures appear frequently.
False
At the end of the fetal period, the head size is one-third the length of the body.
False
During the fetal period, the limbs increase in size from one-tenth to one-half the fetal length.
False
Fetuses are more vulnerable to drugs, radiation, and microbes during the fetal period than they were as embryos.
False
The gender of the fetus becomes distinguishable from external genitals during the embryonic period.
False
During the fetal period, brain development slows down significantly.
False
A fetus typically assumes an upright position during the fetal period.
False
At 32 weeks, testes are usually in scrotum in full-term male infants.
False
Fetal body fat reaches its peak percentage at 12% before birth.
False
Even after birth, an infant is completely developed and does not require any additional time for development.
False
The main force responsible for embryonic folding is the different rates of growth of various parts of the embryo.
True
The term 'organogenesis' specifically refers to the development of body organs and systems during the fourth through eighth weeks of embryonic development.
False
The primitive gut differentiates into an anterior foregut, a posterior hindgut, and an intermediate midgut.
False
During the fifth week of development, there is considerable growth in the limbs due to rapid brain development.
False
By the end of the sixth week of development, the head grows even larger relative to the trunk.
True
The heart prominence is a distinct projection on the dorsal surface of the embryo.
False
The otic placode appears around 22 days after fertilization and is a sign of developing eyes in the embryo.
False
The lateral folds in embryonic development form as the lateral margins bend dorsally.
False
The upper limb buds begin their development by the middle of the fourth week.
False
During organogenesis, all major body systems have already begun to develop by the end of the eighth week.
True
Match the following fetal development stages with the corresponding descriptions:
End of the fetal period = Head size is one-quarter the length of the body Beginning of the fetal period = Head constitutes half the length of the body Mid-fetal period = Head is half the length of the body Late fetal period = Head becomes more proportionate to rest of body
Match the following fetal developments with their corresponding characteristics:
Around 24 weeks = Fetus is commonly felt moving by mother Between 28-32 weeks = Red bone marrow is major site of blood cell production Around 38 weeks = Circumference of fetal abdomen is greater than head At full term = Skin usually bluish-pink, with 16% body fat
Match the following about fetal body changes with their corresponding features:
Peak body fat percentage before birth = 12% with visible toenails Development of eyes and ears = Eyes fully developed, ears low set Appearance near birth = Skin pink and wrinkled, substantial weight gain Appearance at 28-32 weeks = Body fat 8%, smooth skin
Match the following fetal growth characteristics with their corresponding stages:
Limbs increase in size from one-eighth to one-half fetal length = Beginning of fetal period Rapid brain development = Around 22 days after fertilization Fetus assumes upside-down position = Later stage of fetal development Very rapid brain development = During fifth week of development
Match the following features of fetal development with their corresponding periods:
Fetal growth rate remarkable in second half of intrauterine life = Fetal period Fetus less vulnerable to damaging effects of drugs, radiation, and microbes = Fetal period Development slows down but lower limbs continue to lengthen = Later stage of fetal period Fetus appears even more humanlike = Mid-fetal period
What are the two distinct parts of the placenta by the beginning of the twelfth week?
Fetal portion (from the chorion) and maternal portion (from the endometrium of the uterus)
How do oxygen and nutrients move between maternal and fetal blood in the placenta?
Oxygen and nutrients diffuse from maternal blood into fetal blood
Which viruses are able to cross the placenta barrier according to the text?
AIDS, German measles, chickenpox, measles, encephalitis, and poliomyelitis
What substances can freely pass through the placenta and potentially cause birth defects?
Certain drugs, alcohol, and substances
What is the protective function of the placenta against microorganisms?
Most microorganisms cannot pass through the placenta
Why is the development of the placenta considered unique?
It develops from two separate individuals, the mother and the embryo
During which week of fetal development does the head size transition from being half the length of the body to only one-quarter?
End of the fetal period
What is the percentage of total body mass that body fat reaches in a full-term fetus?
16%
At what stage of development does the fetus assume an upside-down position?
Around 28 to 32 weeks
What is the proportion of body fat in a fetus with visible toenails?
3.5%
At what point does the upper limb development begin in the embryo?
Middle of the fourth week
When does the fetal abdomen circumference become greater than that of the head?
Around 38 weeks
What percentage of total body mass does body fat reach its peak before birth?
16%
During which fetal stage does the fetus experience substantial weight gain and have pink, wrinkled skin?
Late fetal stage
What are the components of the umbilical cord and their respective functions?
Two umbilical arteries carry deoxygenated fetal blood to the placenta, while one umbilical vein carries oxygen and nutrients from the mother to the fetus.
Explain the process of embryonic folding and its significance in development.
Embryonic folding is the transformation of a flat embryonic disc into a three-dimensional cylinder, mainly driven by the rapid longitudinal growth of the nervous system. This process is crucial as it allows the embryo to form distinct body structures and positions, such as the heart and mouth.
Describe the development of pharyngeal arches during embryonic development.
Pharyngeal arches are paired structures that begin to develop on the surface of the embryo around the 22nd day after fertilization. Each arch consists of ectoderm, endoderm, and mesoderm, and contains an artery, a cranial nerve, cartilaginous skeletal rods, and muscle tissue.
What are the key developments in the fifth week of embryonic development?
The fifth week is marked by rapid brain development, considerable growth in the head, substantial limb development, and the formation of a four-chambered heart.
Discuss the differentiation of the primitive gut during organogenesis.
The primitive gut differentiates into an anterior foregut, an intermediate midgut, and a posterior hindgut to form the digestive canal.
Explain the appearance and significance of the otic placode during embryonic development.
The otic placode is a thickened area of ectoderm that appears around 22 days after fertilization, signaling the development of the internal ear. This structure is crucial for the formation of the auditory system.
Learn about the formation and functions of the placenta during pregnancy. Discover how the placenta acts as an interface for nutrient and waste exchange between the mother and the developing embryo. Explore the unique characteristics of the placenta as it develops from both maternal and fetal tissues.
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