Development Flashcards
What are the three main regions of the nervous system?
Central nervous system (CNS), peripheral nervous system (PNS), autonomic nervous system (ANS)
The nervous system is divided into these three primary components.
What is neurulation?
The process of neural tube formation during the development of the nervous system
Neurulation involves the elevation of the lateral edges of the neural plate and the formation of the neural groove.
What happens by the end of the third week of development in neurulation?
The lateral edges of the neural plate become elevated to form neural folds
The midregion of the neural plate depresses to form the neural groove.
Where does fusion of the neural folds begin?
In the cervical region at the fifth somite
This is where the neural tube starts to form.
What is the neuroectoderm?
The tissue that develops into the nervous system
Closure of the caudal neuropore marks the completion of neural tube formation.
What are neural tube defects?
Conditions that result when neural tube closure fails to occur
Examples include anencephaly and spina bifida.
What is anencephaly?
A condition where the neural tube fails to close in the cranial region
This results in the absence of a major portion of the brain, skull, and scalp.
What is spina bifida?
A condition where closure of the neural tube fails anywhere from the cervical region caudally
This can lead to defects in the spinal cord and vertebrae.
What does the neural crest develop into?
Dorsal root ganglia and ganglia of the autonomic nervous system
The neural crest cells migrate to form various structures in the nervous system.
Fill in the blank: By the end of the third week, the lateral edges of the neural plate become elevated to form _______.
neural folds
True or False: The neural tube is formed before the neural folds approach each other.
False
The neural tube forms as the neural folds approach and fuse.
What role do signaling molecules play in neurulation?
They are involved in the formation and growth of the neural tube
Members include Sonic hedgehog (SHH) and bone morphogenic proteins (BMPs).
What is the significance of the caudal neuropore closure?
It marks the completion of the neural tube formation
This event is crucial for proper development of the nervous system.
What is spina bifida?
A congenital condition resulting from incomplete closure of the neural tube, leading to spinal cord and nerve damage.
Spina bifida can lead to physical and neurological impairments depending on its severity and location.
What are the three layers of the neural tube?
- Ependymal layer (ventricular layer)
- Mantle layer (intermediate layer)
- Marginal layer
Each layer has distinct functions and cell types involved in neural development.
What is the role of the sulcus limitans?
Divides the lateral plate into a dorsal alar plate and a ventral basal plate within the central canal.
The sulcus limitans is crucial for the organization of sensory and motor pathways.
What are the two types of neuroblasts based on their position relative to the sulcus limitans?
- Neuroblast (nucleus far from sulcus limitans) → somatic function
- Neurchlast (nucleus close to sulcus limitans) → visceral function
This distinction is important for understanding the functional organization of the spinal cord.
What characterizes neuroepithelial cells?
They exhibit a high degree of mitotic activity and form a thick pseudostratified epithelium (neuroepithelium).
Neuroepithelial cells are essential for the formation of the nervous system.
What are the stages in the formation of nerve cells?
- Stage of apolar neuroblast
- Stage of bipolar neuroblast
- Stage of unipolar neuroblast
These stages reflect the differentiation of neuroblasts into various neuron types.
What does the alar plate contribute to in spinal cord development?
Cell bodies in the alar plates form the dorsal gray columns, which are involved in sensory processing.
The dorsal columns are essential for transmitting sensory information to the brain.
What does the basal plate contribute to in spinal cord development?
Cell bodies in the basal plates form the ventral and lateral gray columns, associated with motor functions.
The basal plate is critical for the development of motor neurons.
Fill in the blank: The spinal cord in neonates terminates at the level of the _______.
second or third lumbar vertebra
This positioning changes as the child grows, with the spinal cord typically ending at the first lumbar vertebra in adults.
True or False: The vertebral column grows more rapidly than the spinal cord.
True
This growth discrepancy leads to the termination of the spinal cord at different vertebral levels in neonates compared to adults.
What is the cauda equina?
A bundle of spinal nerve roots that form below the end of the spinal cord (conus medullaris).
The cauda equina is essential for innervating the lower limbs and pelvic organs.
