Ch15 Development and Aging Pt1 Flashcards
When does nervous system development begin?
18 days after fertilization (gestation)
What are the 4 stages of nervous system development?
Neural plate, neural groove, neural tube, and neural crest
What forms the basic structure of the nervous system?
Embryonic neural tube and neural crest
The neural tube forms what?
The brain and spinal cord
The neural crest forms what?
The autonomic and sensory ganglia as well as the adrenal medulla
Where does the neural tube first develop?
In the lower cervical region
Where does the neural tube first “zip up”?
In a cranial direction
Where does the neural tube end up closing?
Caudally, towards the sacrum
By when does the neural tube close?
By 24 days gestation
The neural tube defect, anencephaly, is caused by what?
Incomplete closure of the cranial end of the neural tube. The forebrain typically fails to develop
The neural tube defect, spina bifida, is caused by what?
Incomplete closure of the caudal (sacral) end of the neural tube
What happens in spina bifida?
Meninges protrude out of the back
Meningocele, a type of spina bifida, results in what?
An incomplete vertebral arch but the spinal cord remains in place
Myelomeningocele, a type of spina bifida, results in what?
Portions of the spinal cord bulge into the sac of meninges
What are some effects of having spina bifida?
Paralysis, sensory loss of extremities, loss of bowel and bladder control
Where does the brain develop from?
The cranial end of the neural tube
What are the structures of the forebrain?
Cerebral cortex, subcortical nuclei, thalamus, and hypothalamus
What are the structures of the hindbrain?
Pons, cerebellum, and medulla oblongata
The forebrain undergoes tremendous growth, whereas the midbrain and hindbrain remain relatively small. True or false
True
What do neural crest cells form?
The autonomic nervous system, somatosensory neurons and receptors, and part of the adrenal gland (adrenal medulla)
Where are neural crest cells found?
They migrate throughout the body
Basic organizational structure of the nervous system is in place by how many weeks of gestation?
12
Neurons continue to divide to compose how many neurons?
100 billion
What are the 3 processes involved in nervous system development?
Migration, differentiation, and myelination
What is migration?
Neurons moving to their proper location
What is differentiation?
Neurons acquiring specific structure and specialized function
What does myelination do?
Speeds up transmission of action potentials, beginning at 20 weeks gestation
Synapses are formed from what?
Experiences and movement
Synapses that are used frequently are strengthened. True or false
True
What is the term given for synapses that are not used frequently?
Synaptic pruning
Periods during development in which large numbers of synapses are formed are called what?
Critical periods
What can happen as a result of disruption of synapse building during the critical periods?
Functional deficits
How much does a baby’s brain grow in size over the first year?
Double the size
What percentage of a child’s energy goes towards growing the brain?
50%
What is Arnold-Chiari malformation?
When the brainstem and cerebellum protrude down into the spinal canal
What is Type 1 Arnold-Chiari malformation?
Herniation of cerebellar tonsils & inferior medulla
What is Type 2 Arnold-Chiari malformation?
Type 1 PLUS hydrocephalus due to blockage of cerebrospinal fluid.
Arnold-Chiari type 2 malformation is frequently associated with?
Spina bifida
What is cerebral palsy?
Non-progressive motor disorder resulting from neural damage
