Development of the peripheral nervous system Flashcards
Neural tube becomes what?
Brain and spinal cord
What is segmentation?
Division into brain and spinal bcord
Development of the nervous system begins when?
3rd week Ectoderm (outer tissue layer of embryo) thickens → neural plate → folds inward → neural groove→sides of neural groove (neural folds) come together and make a “roof” at around 3rd week→ end of 4th week =completely fused → neural tube (under the fused roof) → brain and spinal cord
What comes from the neural tube after closing?
Bulges and bends appear→4th week=3 bulges present (primary vesicles)
What are the 3 bulges (primary vesicles)?
Prosencephalon (→cerebrum(most anterior)) Mesencephalon (→midbrain) Rhombencephalon (→ stem and cerebellum)
(End of the neural tube becomes spinal cord)
Neural tube’s bulges
Neural tube develops and looks more like the brain
True
Cerebrospinal fluid tapping is done during a lumbar puncture at L4-L5 because you want to avoid the spinal cord that terminates at L2-L3
True
Tethered Cord Syndrome
Neurological disorder. Spinal cord is stuck and pulled down too far (pinned down). Thick/short filum terminale
In children, symptoms include: tumors on lower back, foot/spinal deformities, weakness in legs, low back pain, scoliosis, inability to control urine
Can go undiagnosed until adulthood when pain and sensory/motor, loss of bowel/bladder problems emerge
Gray matter
Cell bodies of neurons
White matter
Axons
What are Neuroglia cells?
Supporting cells of CNS
Insulate, nourish, support/protect neurons
What layer contains axons?
Marginal layer
What regulates neuronal differentiation via transcription factors?
TGF-β and SHH
What controls sensory neuron differentiation?
↑TGF-β activate PAX3/7→ control sensory neuron differentiation
What controls motor neuron formation?
↑SHH and ↓ TGF-β → activate PAX6 and motor neuron formation
Which side of the spinal cord is for Afferent/Efferent nerves?
Afferent (input) = DORSAL
Efferent (output) = VENTRAL
Somatic vs Autonomic Nervous System
- Somatic: voluntary
- Receptors for touch, pressure, temp, pain- GSA
- Motor (efferent) GSE
- Autonomic: involuntary, maintains homeostasis
Selective Dorsal Rhizotomy
- Nerves are separated and identified with electrical stimulation
- Certain sensory nerve fibers are then cut
- Nerves that lead to too much muscle tone (cerebral palsy) are cut
- Provides relief from chronic pain
Congenital insensitivity to pain (CIP)
Rare condition when person can’t feel pain
(mutation in SCN9A)
Self-mutilation, absence of pain, damage to oral tissues, tongue=characteristics
Characteristics of ANS
- Actions are automatic/involuntary
- GVA (general visceral afferent) and GVE
- 2 neurons (preganglionic and postganglionic (both part of GVE)) in path from CNS → effector
- Somatic has 1 neuron
Subdivisions of ANS
Sympathetic: Fight or flight
Parasympathetic: rest and digest
