Development of the Nervous System Flashcards
Genes reside in
the chromosomes
Chromosomes reside in
nucleus of the cell
Karotype
a person’s unique collection of chromosomes
How many pairs of chromosomes?
23
How many individual chromosomes?
46
Diseases associated with chromosomes
Down syndrome
Turner syndrome
Prader-Willi syndrome
Fragile X syndrome
Types of cell division
Meiosis and Mitosis`
Mitosis
cell duplicates all contents and splits
- 2 identical daughter cells
- critical controlled genes
(carbon copy of itself)
If an identical copy of cell is not created during Mitosis..
this can cause cancer
Meiosis
two step process with the goal being a correct number of chromosomes
- makes genetic differences
Events during dorsal induction
neural tube formation
casual eminence development
Events during ventral induction
prosencephalic development
cleavage
midline formation
neural proliferation
neuronal migration
cortical organization
myelination
cerebellar & brainstem development
Dorsal Induction
Period when neural tube is formed, brain and spinal cord develop out of neural tube
Neural tube defects
Failure of neural tube ends to close
- Encephalocele
- Anencephaly
- Spina Bifida
Encephalocele
part of the brain protrudes from the skull
Anencephaly
- brain development ceases @ the brainstem
- no cerebral hemispheres
Spina bifida
cyst on back that may involve the spinal cord
Ventral Induction
Period when face and brain develop out of superior end of neural tube
Developmental Divisions
Telencephalon
Diencephalon
Mesencephalon
Mentecephalon
Myelencephalon
Telencephalon
- end of the brain, outer layer of cerebrum
- cerebral cortex, basal ganglia, olfactory bulbs
Diencephalon
thru the brain
- relay station
- thalamus, hypothalamus, epithalamus, subthalamus
Mesencephalon
middle of the brain
- midbrain (front of brainstem)
- sensory, motor, vision, arousal, etc
Mentecephalon
Hind brain
- pons, cerebellum
Myelencephalon
Medulla
- connects brain to spinal column and vice versa
Neural proliferation
- Neurogenesis (birth of new neurons)
- new neurons become gray/white matter
- born out of spinal cord & brainstem
Interruptions in neural proliferation ..
may result in microcephaly where children have abnormally small heads/brains
Neuronal Migration
neurons move in wavelike fashion to the correct position in cerebral hemispheres
- chemical reeling signals them where to stop
When does neuronal migration end
about 20 weeks GA and once it stops the 6 layers of cerebral cortex are established
Cortical organization & Synapse formation
Once neurons are at their intended spot, they sprout dendrites and axons
- synaptogenesis
- synaptic pruning
synaptogenesis
synapses begin to form between neurons
synaptic pruning
eliminates unneeded connections
Myelination
- neuron axons are coated with myelin
- takes about a year after birth to reach its peak
- infants gain greater control of their body & communicate verbally
Failure during myelination
hypomyelination: reduced ability to form myelin and can lead to intellectual disability
Adolescent brain
- profound brain development that is not complete until age 25
- includes synaptic pruning and thinning of gray matter
- very plastic
- explains behavior
During adolescence teens rely on..
feelings/impulses more than logic/planning
- age 10-11 for girls
- age 11-12 for boys
Aging and the brain
- lose neural circuits
- lose plasticity
- cortex thins due to dendrite thinning
- neurotransmitter levels & receptor sites decrease
^ can lead to loss of memory, attn, learning, language
