Development of the peripheral nervous system

Question 1

Neural tube becomes what?

Answer 1

Brain and spinal cord

Question 2

What is segmentation?

Answer 2

Division into brain and spinal bcord

Question 3

Development of the nervous system begins when?

Answer 3

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

Question 4

What comes from the neural tube after closing?

Answer 4

Bulges and bends appear→4th week=3 bulges present (primary vesicles)

Question 5

What are the 3 bulges (primary vesicles)?

Answer 5

Prosencephalon (→cerebrum(most anterior)) Mesencephalon (→midbrain) Rhombencephalon (→ stem and cerebellum)

(End of the neural tube becomes spinal cord)

Question 6

Answer 6

Neural tube’s bulges

Question 7

Neural tube develops and looks more like the brain

Answer 7

True

Question 8

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

Answer 8

True

Question 9

Tethered Cord Syndrome

Answer 9

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

Question 10

Gray matter

Answer 10

Cell bodies of neurons

Question 11

White matter

Answer 11

Axons

Question 12

What are Neuroglia cells?

Answer 12

Supporting cells of CNS

Insulate, nourish, support/protect neurons

Question 13

What layer contains axons?

Answer 13

Marginal layer

Question 14

What regulates neuronal differentiation via transcription factors?

Answer 14

TGF-β and SHH

Question 15

What controls sensory neuron differentiation?

Answer 15

↑TGF-β activate PAX3/7→ control sensory neuron differentiation

Question 16

What controls motor neuron formation?

Answer 16

↑SHH and ↓ TGF-β → activate PAX6 and motor neuron formation

Question 17

Which side of the spinal cord is for Afferent/Efferent nerves?

Answer 17

Afferent (input) = DORSAL

Efferent (output) = VENTRAL

Question 18

Somatic vs Autonomic Nervous System

Answer 18

• Somatic: voluntary
  
  • Receptors for touch, pressure, temp, pain- GSA
  • Motor (efferent) GSE
• Autonomic: involuntary, maintains homeostasis

Question 19

Selective Dorsal Rhizotomy

Answer 19

• 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

Question 20

Congenital insensitivity to pain (CIP)

Answer 20

Rare condition when person can’t feel pain

(mutation in SCN9A)

Self-mutilation, absence of pain, damage to oral tissues, tongue=characteristics

Question 21

Characteristics of ANS

Answer 21

• 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

Question 22

Subdivisions of ANS

Answer 22

Sympathetic: Fight or flight

Parasympathetic: rest and digest