De/Regeneration and Diseases of the NS Flashcards
Charcot-Marie-Tooth disease is:
A group of disorders that affect the peripheral nerves. Mutations prevent the sheaths from forming gap junctions essential for metabolite transfer. Myelin twists around the axon like a jelly-roll cake and prevents dissipation of the electrical signals.
Where and what is Multiple Sclerosis?
CNS demyelinating disease. Presence of multifocal plaques (scar tissue deposited at the sites of demyelination). Presence of antibodies indicates autoimmune disease.
Affects upper motor neuron.
What are symptoms of Multiple Sclerosis?
Paresthesias, visual disturbances, internuclear ophthalmoplegia, extremity incoordination and clumsiness, paresis with spasticity (hypereflexia and hypertonia) (upper motor neuron symptoms). Temperature exacerbates.
Characterized by spontaneous unpredictable remissions and relapses at irregular intervals.
Where and what is Guillain Barre Syndrome?
Acute demyelinating peripheral neuropathy (PNS). Autoimmune; it usually follows a respiratory infection.
Affects the lower motor neuron.
What are the symptoms of Guillain Barre Syndrome?
Glove and stocking pattern of sensory loss or paresthesia, paresis with hyporeflexia and atrophy (lower motor neuron symptoms).
It can be life threatening even though remission is possible.
Where and what is Amyotrophic Lateral Sclerosis?
A disease of middle and late life (rarely seen in patients under 30) involving upper and lower motor neurons.
Nerve cell degeneration.
What are symptoms of Amyotrophic Lateral Sclerosis?
No sensory or autonomic symptoms.
Often the first manifestation is hand weakness and atrophy accompanied by generalized hyperreflexia, which progress rapidly throughout the body.
90% of the patients expire within 6 years due to respiratory insufficiency.
Where and what is Myasthenia Gravis?
Autoimmune disease of the neuromuscular junction (PNS) characterized by fluctuating weakness and fatigueability of skeletal muscle due to nicotinic acetylcholine destruction in the neuromuscular junction.
What are symptoms of Myasthenia Gravis?
Ptosis, affects ocular, facial, and muscles that function in phonation (dysphonia) and swallowing (dysphagia); trunk and extremity weakness might come later in the course of the disease; 15% of the patients have a thymoma
Unpredictable course with spontaneous remissions; severe cases result in pulmonary failure due to respiratory paralysis
After injury of an axon divides the neuron, the proximal part of the axon and the cell body are likely to __________; if not, the cell body __________.
Die by apoptosis; undergoes chromatolytic reaction (axon reaction)
What occurs during a chromalytic reaction?
The proximal part will have an eccentric nucleus, Nissl substance fragmentation, increase of RNA and protein synthesis, changes in the expression of the neuron’s genes.
Where and what is Wallerian degeneration?
The distal segment of the injured axon undergoes Wallerian degeneration. This includes axonal degeneration, myelin sheath fragmentation, then axonal and myelin debris is enveloped and destroyed by microglia.
What is transneuronal anterograde degeneration?
The postsynaptic neuron is affected because of lack of input, and eventually atrophies and dies depending on the extend of the neuronal damage.
What is transneuronal retrograde degeneration?
The neuron that provides the injured cell with input undergoes changes: synaptic space increases and is interrupted by glial processes: Schwann cells in the peripheral nervous system, and Astrocytes or microglia cells in the central nervous system.
Which neurons have a higher capacity to regenerate?
PNS neurons
