Cellular Neuro Science ppt 5-6 Flashcards
What does the structure of the neuron consist of?
Soma
Dendrites
Axon
What is the soma?
Consists of nucleus & cytoplasm (ER, GA, Mito, cytoskeleton and microtubules) NISSL bodies (modified RER)
What are the dendrites?
It is a tapering process from the soma that forms the receiving zone of the neuron, conduct electricity toward the body. Contain Nissl bodies and GA.
What is the axon?
Longest Process arrises from the axon hillock (continues as the unmyelinated proximal part called initial segment.
Initial segment (spike initiation some) where the action potential arises.
NO NISSL, ER or GA.
Does contain- vesicles, mitochondria and neurofibrils.
How are neurons classified based on number of processes?
Multipolar- many from soma (spinal motor)
bipolar- two processes (retinal)
Unipolar- single process (ANS)
How are neurons classified based on length of the axon?
Golgi type 1- LONG (cortical motor neurons)
Golgi type 2- short (cortical inhibitory)
What are glial cells?
Types and functions?
Supporting cells.
smaller but more numerous than neurons.
- Astrocytes- BBB
- Ependymal cells- lining of ventricles CSF
- Oligodendrocytes- CNS myelin sheath
- Microglia- immune cells.
Schwann cells – PNS-myelin sheath
Satellite- PNS support
What is the myelin sheath?
A multilayer lipid and protein covering that electrically insulates the axon of a neuron and increases the speed of impulse conduction.
Reduces energy expanses and protects the axon.
Schwann vs oligodendrocytes
Schwann- wrap around a single axon
Oligodendrocyte- nucleus in the middle wraps a number of axons
What is demyelination?
Damage to the myelin sheath caused by INFLAMMATION, viral infections, physical compression or demyelinating disorders
What are the demyelinating disorders?
MS Guillain Barre Charcot Marie Progressive multifocal leukoencephalopathy Central Potine myelionylsis
What is MS?
Multiple Sclerosis.
inflammatory autominute disorder. Autoantibodies vainest the myelin basic protein of OLIGODENDROCYTES.
CNS demyelination.
Clinical features of MS?
Scanning Speech
Intentional tremor
Nystagmus
Positive Babinski
Diagnos of MS
Increased polyclonal IgG
Myelin Basic protein
MRI: multifocal pages of periventricular demyelination in white matter.
What is Guillain Barre Syndrome?
Inflammatory autoimmune demylination of the peripheral motor ventral roots.
Associated with infection. (campylobacter jejuni)
Clinical features of Guillain Barre?
no fever.
Areflexic (hyporeflexive). Symmetric ascending muscle weakness. (begins lower extremities)
Paresthesia in the distal lower extremities
Diagnosis of Guillain Barre.
Treatment and Prognosis
Elevated CSF protein with normal cell count.
papilledema and clinical presentations.
Treatment- respiratory support. plasmapheresis and IV immunoglobulins.
Prognosis- Death ue to secondary pulmonary complications. Full recovery with supportive care
What is Charcot Marie Tooth Disease?
demyelination, which is caused by a mutation in one of the connexin genes expressed in the Schwann cells. (no functional gap junctions)
affect both motor and sensory nerves.
Clinical Features of Charcot Marie?
- Weakness of the foot and lower leg muscles
- foot drop and a high-stepped gait
- Foot deformities, such as high arches and hammertoes
- The lower legs may appear like an “inverted champagne bottle”
- Weakness and muscle atrophy can occur in the hands
- Mild or severe neuropathic pain
- Hypo-reflexia
Treatment and Prognosis of Charcot Marie
No cure. PT. leg braces
Normal Life Expectancy
What are the two types of axonal transport?
- Anteriograde- Kinesin ( fast transport microtubule dependent)
- Retrograde- Dynein (microtubule dependent)