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26 Cards in this Set
- Front
- Back
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What is the primary function of the astrocyte?
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Connecting them to their nutrient supply, the blood capillaries.
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What is the primary function of the microglia?
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Phagocytize microorganisms or neuronal debris.
Very impt b/c immune system cells don't have access to the CNS. |
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What is the primary function of the ependymal cells?
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They line the central cavities of the brain and spinal cord.
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What is the primary function of the oligodendrocytes?
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They line the thicker neurons in a covering called a myelin sheath.
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What are the structural units of the nervous system?
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Neurons (nerve cells)
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What are the 3 special characteristics of nerve cells?
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1. Longevity - can last a lifetime
2. Amitotic - lose their ability to divide 3. High metabolic rate |
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Where does electrical signaling take place on the neural body?
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The plasma membrane
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What standard organelle do neurons lack?
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Centrioles. They play a key role in division by forming the mitotic spindle.
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What are neurons in the CNS called?
In the PNS? |
Nuclei
Ganglia |
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What are bundles of neuron processes called in the CNS?
In the PNS? |
Tracts
Nerves |
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What are the 2 types of neuron processes?
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Dendrites & axons.
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T/F?
Virtually all organelles present in the cell body also occur in the dendrites. |
True
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T/F?
Dendrites help convey nerve impulses. |
False. They convey incoming messages toward the cell body that are just short distance signals ("graded potentials")
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How many telodendria or terminal branches are found at the end of a typical axon?
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10,000 or more
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What two organelles do axons lack that cell bodies and dendrites have?
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Nissl bodies and a Golgi apparatus.
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T/F?
Dendrites are always unmyelinated? |
True.
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What is the myelin sheath actually composed of?
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It is the Schwann cell that is tightly coiled around it, like guaze around a finger.
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What is the neurilemma?
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The exposed part of the Schwann cell plasma membrane, as well as the nucleus & cytoplasm of the Schwann cell.
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What are the 3 possible structural classifications of neurons?
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Multipolar
Bipolar Unipolar |
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What are the 3 possible functional classifications of neurons?
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Sensory
Motor Interneurons |
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What is voltage?
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The measure of potential energy generated by separated charge.
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What does Ohm's law tell us?
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The greater the voltage, the greater the current.
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What are the 3 types of ion channels?
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Chemically-gated/ligand-gated
Voltage-gated Mechanically-gated |
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What is the resting membrane potential?
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When the voltage across the membrane of a neuron is -70 mV. The inside is negatively charged relative to the outside.
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Excitable cells are very permeable to _____ and only slightly permeable to ______.
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K+
Na+ |
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At what point does potassium stop diffusing out of the cell?
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Until the electrical potential is equal but opposite to the force from the concentration gradient.
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