Injury and Repair of the Nervous System

Describe the changes that occur after sensory nerve injury: distally and proximally to the injury in the dorsal root ganglion Describe the process of nerve regeneration in the PNS and the determinants of its success 3. Explain why the possibilities for repair are limited in the CNS

Axons are grouped together is specially arranged motor or sensory bundles called _________ __enclosed by__ ___________.

fascicles

perineurium

The connective tissue around an individual nerve axon is the

endoneurium

The **__________** is a connective tissue layer that surrounds groups of fascicles within a peripheral nerve. 

epineurium

The proximal cut ends of the nerve fibres form **_______** __and start to grow back down inside the sheaths guided by chemical factors__ _________ on the surface of the Schwann cells

growth cones

CAMs

**Disconnected axons and cell bodies degenerate** via a programmed cell death pathway called

**Wallerian degeneration**.

Schwann cells phagocytose _____________ debris until empty endoneurial tubes remain.

axonal and myelin

The process of Wallerian degeneration is a major roadblock to rapid and complete

nerve regeneration

The ___ __receptors act on__ to sustain elevated intracellular cAMP levels and, in turn, promote expression of growth-associated genes for axon outgrowth.

trk

adenyl cyclase

What initiates gene transcription and translation of neurotrophins and their trk receptors via Protein Kinase A?

cAMP

**myelin sheaths in the CNS are produced by _________** and not by Schwann cells

**oligodendrocytes**

**Spinal cord trauma** produces a site of

primary cell death

Macrophages and microglia engulf debris resulting in the injury leaving a

glial scar

Brown Sequard syndrome

**is a neurological condition that results from an injury or damage to one side of the spinal cord**. This condition results in weakness or paralysis on one side of the body (hemiparaplegia) and a loss of sensation on the opposite side (hemianesthesia).