Lecture 6B: CNS Development Flashcards
T/F: As a consequence of developmental events, structures belonging to functionally unrelated systems often come to lie next to one another.
True.
What is Down’s Syndrome?
A chromosomal disorder caused by the presence or all or part of an extra 21st chromosome.
An agent or environmental factor that causes malformation of an embryo is known as a ______.
Teratogen
In fetal alcohol syndrome, there is an association between the severity of facial structural defects and _______.
Midline brain anomalies.
T/F: Fetal Alcohol syndrome is the most common genetic cause of mental retardation.
False.
Down’s Syndrome is the most common genetic cause of mental retardation.
What structure of the brain is often associated with structural anomalies in a child born with fetal alcohol syndrome?
Corpus callosum
List 4 characteristics of children with fetal alcohol syndrome.
1) Small birth weight
2) Problems eating and sleeping
3) Difficulty seeing and hearing
4) Physical disabilities (ie. abnormal muscle tone)
5) Trouble following directions
6) Difficulty paying attention and learning in school
7) Behavioural deficits: trouble getting along with others and controlling behaviour
T/F: The embryonic stage is from conception to 2 weeks.
False.
This is the pre-embryonic stage.
The fetal stage is from _____ until ____.
End of 8th week; birth
What major milestone occurs during the embryonic stage?
Development of systems and organs (ball of cells has begun to differentiate).
What major milestone occurs during the fetal stage?
Nervous system continues to develop and mylelination of neurons begins.
____ to _____ marks the embryonic stage.
End of week 2; end of week 8
At what developmental stage in utero does the basic nervous system (besides myelination) begin to form?
Embryonic stage
When do three germ cell layers become established for form the embryo?
Beginning of 2nd week
What germ layer develops into all major tissues of the nervous system and the skin?
Ectoderm
T/F: The endoderm is the outermost layer of the the three germ cell layers.
False.
The endoderm is the innermost layer.
T/F: The mesoderm develops into bones of skeleton, muscles and the digestive tract.
False.
The mesoderm develops into bones of the skeleton, muscles and circulatory system.
The endoderm develops into the digestive tract, liver and ______.
Respiratory system.
What is the thickening of the ectoderm, form which the nervous system begins, known as?
Neural plate
The neural plate begins to fold at its lateral edges to form the ______. The neural folds then progressively fuse to form the _____.
Neural groove; neural tube
What is the name of the process by which the neural plate becomes the neural tube?
Neurulation
Closure of the neural tube is initiated at the precursor area to the _____.
Upper cervical spine
On what day does neurulation occur in embryonic development?
Day 22
What are 2 cephalic and 1 caudal conditions that can result from failure of the neural tube to completely close?
1) Anencephaly
2) Encephalocele
3) Spina bifida - caudal