Neuons
Terms
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- What is the diameter of a neuron cell body?
- 10 – 50 microns
- The longest axon projections from...
- cortex and project down to the bottom of the spinal cord
- Diameter of axon?
- 0.2-20 μm diameter
- Longest axon
- one meter in length
- Most vertebrate neurons are?
- Multipolar neurons
- Neurons found in the retina and olfactory epithelia are usually?
- bipolar neurons
- Neurons of the dorsal root ganglion are?
- Psuedo-unipolar nuerons
- Unipolar neurons are found where?
- Authnomic nervous system, and invertebrates
- These nerve cells have no dendrites?
- pseudo-unipolar
- Cajal realized that...
- each neuron is an individual entity and that neurons interact with each other through synaptic communication
- Cajal's doctrine is called...
- The neuron doctrine
- 4 forms of cell-cell communication:
-
1. Endocrine communication
2. Paracrine communication
3. Synaptic communication
4. Contact-dependent communication - Synapses can occur on all parts of the neuron. Synapses that occur on the axon are called?
- Axo-axonic syanpses
- Synapses that occur on the dendrite are called?
- Axo-dentridic synapses
- Syanpses that occur on the soma are called?
- Axo-somatic synapses
- True or false: a synapses occuring on the cell body or axon terminal would have a much greater effect on the output of the cell, as compared to one of the tens of thousands of synapses that occur on the dendrite
- True
- Size of synaptic cleft?
- 200-300Ã…
- Synaptic terminal contains...
- large number of mitochondria and vessels of neurotransmitter
- Size of neurotransmitter vesicles...
- 400-6000 Ã… diameter, containing neurotransmitter and neuropeptide substances for released
- Besides neurons, what other cells are intimately involved in the functions of the nervous system?
- Glia cells
- Glia cells are separated into what 2 groups?
-
1. Microglia
2. Macroglia - What 2 categories of macroglia are there?
-
1. Myelin-forming cells
2. "Supporting" Cells - Myelin-forming cells in the CNS are called...
- Oligodendrocytes
- Myelin-forming cells in the PNS are called...
- Schwann Cells
- What are the 2 types of Supporting Cells?
-
1. Astrocytes
2. Satellite cells - Astrocytes are in which part of the nervous system?
- CNS
- Satellite cells are in which part of the nervous system?
- PNS
- Whatever we say about astrocytes also applies to...
- Satellite cells
- Again, what is the function of microglia?
-
⬢ Invade brain during fetal development and maintain residence in
parenchyma. Responsible for response to injury to trauma in brain by
proliferation and phagocytosis of debris. Spider-like cells. - Function of astrocytes (and also satellite cells)
-
• Convert to different shapes, depending on function. Intimate associations
with blood vessels, ventricles, neurons, synaptic terminal zones.
• Processes extend around terminals. May serve to control diffusion of
released neurotransmitters.
• Store, buffer and release ions, transmitters. Have receptors, and some even
form synapses.
• Communicate with each other, and with neurons, via gap-junctions.
• High producers of cytokines that “nurse†cells. - Function and location of schwann cells.
-
⬢ Derived from neural crest, serve as support cells and myelinating cells of
the PNS. Can also act as phagocytes, and produce cytokines. - How many neurons does an oligodendrocyte wrap around?
- 1 cells wraps around several axons
- How many neurons does a schwann cell wrap around?
- 1 cell per axon, but it can cover unmyelinated axons
- Name a demyelination disease:
- Multiple Sclerosis
- Schwann cells and satellite cells might be seen in what nerve?
- Peripheral nerves
- This surrounds individual axons, Schwann cells and blood vessels
- Endonerium
- This surrounds groups of fibers to form fasciles:
- Perinerium
- This binds several fasicles into a nerve trunk:
- Epinerium