A1 Neural Development Flashcards
Describe neurulation.
Neurulation is the formation of a neural tube in embryonic chordates.
Cells located in the outer germ layer (ectoderm) differentiate to form a neural plate. The neural plate then folds inwards to form a neural groove. This closes to form the neural tube. The neural tube will elongate as the embryo develops and form the CNS (brain and spinal cord).
What is spina bifida?
A birth defect resulting in the incomplete closure of the neural tube. It limits use of the legs and feet and can cause paralysis of the lower limbs.
Explain spina bifida.
Spina bifida is caused by the neural tube failing to close completely. This results in a malformation of the lower vertebrae which leaves the spinal cord exposed and vulnerable to injury. The severity of symptoms varies and depends on where in the spine the opening occurs. It is associated with a deficiency in folic acid in the diet of the mother.
How are neurons initially produced?
The neural tube contains multipotent neuronal stem cells which can differentiate to form the different types of nerve cells (neurons and glial cells).
Axons grow out of immature neurons in response to chemical stimuli.
Developing neurons form multiple synapses with other neurons.
What is neural pruning?
The loss of unused neurons (by removing excess axons and eliminating their synaptic connections). It is influenced by environmental factors and is mediated by the release of chemical signals from glial cells.
What is neuroplasticity?
Neuroplasticity is the capacity for the nervous system to change and rewire its synaptic connections. It is an adaptive response and enables memory retention and learning. It suggests that stem cells could be used to treat diseases of the brain and CNS.
Discuss gastrulation.
Gastrulation is the production of three germ layers in early embryonic development – ectoderm (outer), mesoderm (middle) and endoderm (inner).
The ectoderm will form the nervous system (via neurulation) and outer surfaces. The mesoderm will form the majority of body organs while the endoderm will form the respiratory and digestive tracts.
