Nerve Flashcards
What does the soma of a neuron contain?
Rough endoplasmic reticulum (called Nissl substance or Nissl bodies)
What do dendrites do?
Transmit information towards the soma
What do axons do?
Arise from the axon hillock and transmit information away from the soma
What are the characteristics of dendrites?
Many per cell Irregular profiles (dendritic spines) Tapered Highly branched Not myelinated Contains ribosomes and RER More neurotubules than neurofilaments
What are the characteristics of axons?
One per cell Smooth profiles Uniform diameter Relatively straight Few branches Often myelinated No RER, ribosomes More neurotubules
What are neuroglia?
Support cells of the CNS/PNS
What do oligodendrocytes do?
Form the myelin sheath
What are the two type of astrocytes?
Fibrous astrocytes
protoplasmic astrocytes
Where are fibrous astrocytes?
Between myelinated nerve fibers (white matter)
Where are protoplasmic astrocytes?
Surround sonata and dendrites (grey matter) and participate in metabolic exchange
Where are ependymal cells?
Ependymal cells line brain vesicles
What do microglial cells do?
Act as brain macrophages
What do schwann cells do in the PNS?
Form the myelin sheath
What do satellite cells do in the PNS?
Surround somata in ganglia
Equivalent of astrocytes in the CNS
What’s the main function of astrocytes?
Structural support, repair processes, blood brain barrier, metabolic exchange
What is the blood brain diffusion barrier (BBB)?
A specialized endothelium lining blood vessel lumens in the CNS
How is the BBB protected from large molecules?
Tight junctions occur between endothelial cells to form a diffusion barrier to large molecules
What proceses does the BBB to move specific cells across the barrier?
Active endo- and exocytosis vesicle pathways for specific transport
What regions of the brain do not have BBB?
Choroid plexus (CSF production), pituitary gland, pineal gland and other ‘circumventricular’ organs
Axons in the PNS are bundled into?
Fascicles
Individual axons with their swan cells are surrounded by?
Endoneurium
What is endoneurium?
Connective tissue containing collagen fibers, fibroblasts and mast cells
What are fascicles surround by in the PNS?
Perineurium
What doe the perineurium help to establish?
A peripheral blood-nerve diffusion barrier
What does the perineurium actively transport?
Nutrients in
Waste out
What kind of cells are in the perineurium?
Stratified squamous layer of ct each decent cell fused by tight junctions
The perineurium can become thicker containing collagen and actin fibers giving it the ability to?
Contract
Epineurium can often be associated with what kind of tissue?
Adipose tissue
What is anterograde (Wallerian) degeneration in PNS?
Atonal degeneration distal to the injury site
