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50 Cards in this Set
- Front
- Back
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What organelles are contained in the cell body of a neuron?
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Nuclei, Golgi, RER, Mitochondria, SER, Lysosomes, Axon Hillock, Neurofilaments and Neurotubules
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What is lipofuscin?
In what population does this seem to accumulate? |
Tertiary lysosomes filled with indigestible pigment.
In the elderly |
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What two organelles help maintain the plasmalemma in a cell body?
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Golgi and RER
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What are Nissl bodies? What do they do?
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Nissl bodies = RER+Free Polysomes
They maintain the large volume of protein components of the cell. |
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Where are nissl bodies NOT located in a cell body?
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in the axon hillock
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Why is the nucleus so big in a cell body of a neuron?
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Large nucleus bc cell body is responsible for metabolism, growth and repair of neurons.
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Besides it's major function of maintaining the plasmalemma, what is another function of the golgi in a neural cell body?
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creating synaptic vesicles
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Why are mitochondria numerous in the cell body?
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Neurons have low energy stores and have a large requirement for O2 and glucose.
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If the axon hillock doesn't contain Nissl bodies...what does it contain?
What originates here? |
Axon hillock contains neurotubules and neurofilaments
Action potential originates in the axon hillock. |
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What is the function of dendrites?
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Dendrites receive information from the axons.
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What two organelles that are present in cell bodies are NOT present in the dendrites?
Why are there so many branches? |
Dendrites do NOT contain Golgi or Nuclei.
To increase surface area possible to receive input. |
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Which way do dendrites direct impulses?
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Dendrites direct impulses TOWARD the cell bodies.
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CNS tissues contains only CELLS. What extra materials does PNS contain?
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PNS contains connective tissue. CNS never contains connective tissue.
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What kind of potential do dendrites receive?
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graded potential
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Axon conducts impulses in which direction?
What is the one exception? |
AXONS conduct AWAY from the cell body.
The one exception is in the sensory PNS. |
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What organelles that the soma has - does the AXON NOT have?
How is this different from the dendrite? |
The axon has NO Golgi, RER OR Nucleus
Dendrites have NO GOLGI or NUCLEUS (but do have RER). |
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What is good to remember visually about "axon collaterals?
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They branch at 90 degrees.
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Which kind of organelle will you find a lot of in an axon?
What is their function? |
An increase in the amount of neurotubules.
Neurotubules carry proteins from the soma to/through the axon. |
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What kind of potential does an axon get?
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Action potential primarily. (Can experience some graded potentials.)
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Where do the axons get proteins?
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Axons don't have a nucleus, golgi or rer - but they DO have lots of neurotubules....
so the proteins from the soma come down these. |
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Why does an axon have retrograde transport?
is this fast or slow? |
The cellular waste returns to the soma to be degraded by the lysosomes or recycled.
fast rate |
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What is one consequence of retrograde transport?
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viral and bacterial have a method of getting to cell body via retrograde transport
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what kinds of things go fast down anterograde axonal transport?
which things go more slowly? |
FAST: synaptic vesicles, mitochondria, glucose, AA's and Ca+
SLOW: proteins |
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What are 3 types of neurons?
What is the most common type? Describe them. |
Multipolar, bipolar and unipolar.
Multipolar neurons. They have one axon and 2 or more dendrites. |
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Describe a bipolar neuron.
are they all myelinated? Function? |
Bipolar neurons have ONE DENDRITE.
SOME are unmyelinated. SPECIAL SENSES. seeing. smelling. |
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What is interesting about the structure of a unipolar neuron?
Where are they found? |
There is an axon on BOTH sides of the soma in a unipolar neuron. (Signal bypasses the soma)
Dorsal Root Ganglia and Sensory part of Cranial nerves. |
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Are their dendrites on a unipolar neuron?
How can you tell? |
yes.
DENDRITES ARE NEVER MYELINATED. |
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Which kind of synapses can be excitatory only?
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Electrical synapses are excitatory only.
Chemical synapses can contain inhibitory neurotransmitters. |
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What are the functional connections between axons and a gland, soma, dendrite or muscle?
What are two kinds of these? Which are faster? Why? |
Synapses.
Chemical or Electrical synapses. Electrical synapses are faster bc there is no synaptic delay w NT's. |
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Why is there very dense cytoplasmic material @ synapse site on either membrane found there?
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There is dense cytoplasmic material at synaptic membrane because there are many mitochondria and vesicles that are furnished by anterograde transport.
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What kind of neural tissue contains cell bodies, axons, dendrites, astrocytes, oligodendrocytes, microglia and capillaries?
What is all that minus the soma called? |
GREY MATTER = cell bodies plus neuropil.
Neuropil = axons, dendrites, astrocytes, oligodendrocytes, microglia and capillaries |
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What is not found in White Matter?
Where is white matter found in the brain? |
NO CELL BODIES.
Just the axons, supporting cells and capillaries. White matter is found deep in the brain. |
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Where is endoneurium found and what is it?
What accessories does endoneurium have? |
Endoneurium is loose connective tissue outside the myelin in the PNS only.
fibroblasts, macrophages and capillaries |
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What is the function of perineurium?
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Perineurium prevents passage of virus/bacteria into the endoneurium.
PERINEURIUM IS MADE OF CELLS. |
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What is the function of epineurium?
Describe its structural characteristics. |
The epineurium protects the nerve cells from direct physical trauma.
This is thick collagen with few fibroblasts. |
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Which kind of "neurium" is make of connective tissues? Which is made of cells?
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EPI and ENDO are made of connective tissue.
PERINEURIUM is made of cells. |
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What are supporting cells in the CNS?
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Astrocytes, oligodendrocytes, microglia and ependymal cells.
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What is a collection of nerve bodies called in the PNS?
What are two types of this? |
A Ganglion.
Sensory and Autonomic |
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What is the function of astrocytes?
Where are they found? |
Astrocytes maintain homeostasis in the CNS. Specifically they remove excess K+ in the extracellular space.
CNS ONLY |
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What is the function of oligodendrocytes?
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Oligodendrocytes produce myelin in the CNS
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What is the function of the microglia cells?
Why are these necessary? |
"macrophages of the CNS".
Microglia are necessary because monocytes (precursors to macrophages) cannot cross the BBB. |
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What are ependymal cells?
What type of cells are these? |
These cells line the ventricles of the brain and the central canal in the spinal cord - they make CSF.
These cells are epithelial. |
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What are they types of supporting cells in the PNS?
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Schwann Cells and satellite cells.
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What is the function of satellite cells?
What is the function of the Schwann cells? |
These surround the soma and dendrites in the PNS. They regulate the environment around ganglion. (Function somewhat unknown)
Schwann - makes myelin around large axons in PNS |
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In the CNS is it possible to have an axon that has no myelin and no sheath?
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Yes. In the PNS you cannot have a non-sheathed cell.
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Sensory ganglia are what kind of neurons?
Do they synapse? What are two types of sensory nerves? |
unipolar. no synapses.
Dorsal Root and Cranial nerves. |
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What kind of nerves are autonomic nerves?
What are two categories of autonomic nerves? |
Motor nerves = MULTIPOLAR
Sympathetic and parasympathetic. |
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What are two kinds of sensory receptors?
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Free nerve endings and encapsulated
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What is one example of free nerve ending type of sensation?
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Skin dermatomes
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Describe what axons are like when then are < 1 um in the PNS
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They are in bundles of about 20 - sheathed but not myelinated.
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