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10 Cards in this Set
- Front
- Back
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Organs and Division of the nervous sytem |
A. CNS- brain and spinal cord
B. PNS- all nerves
C. Autonomic nervous system (ANS) |
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Cells of the nervous system |
Neurons and gila |
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Neurons |
1. Consist of three main parts- dendrites, cell body of neuron, and axon
a. Dendrites- branching projections that conduct impulses to cell body of neuron
b. axon- elongated projection that conducts impusles away from cell body of neuron
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Classifications of neurons according to function |
1. Sensory (afferent neurons)- conduct impulses to the brain and spinal cord
2. Motor (efferent) neurons- conduct impulses away from the brain and spinal cord
3. Interneurons- cnoduct impulses from sensory neurons to motor neurons or among a network of interneurons; also known as central or connecting neurons |
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Glia (neuroglia) |
1. Support cells, bringing the cells of nervous tissue together structurally and functionally
2. Three main parts of glial cells of the CNS a. astrocytes- star shaped cells that anchor small blood vessels to neurons
b. microglia- small cells that move in inflamed brain tissue carrying on phagocytosis
c. ligodendrocytes- form myelin sheaths on axons n the CNS
3. Schwann cells from myelin sheaths on axons of the PNS |
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Nerve |
1. Bundle of peripheral axons
a. tract- bundle of central axons
b. white matter- tissue composed primarily of myelinated axons (nerves or tracts)
c. Gray matter- tissue composed primarily of cell bodies and unmyelinated fibers |
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Nerve coverings |
1. endoneurium- surrounds individual fibers within a nerve
2. Perineurism- surrounds a group of nerve fibers
3. epineurium- surrounds the entire nerve |
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Reflex arc |
1. Nerve impulses are conducted from receptors to efectors over neuron pathways or reflex arcs
2. The simplest reflex arcs are two-neuron arcs- consisting of sensory neurons synapsing in the spinal cord with motor neurons
3. three-neuron arcs consist of sensory neurons synapsing int he spinal cord with interneurons that synapse with motor neurons |
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Nerve impulses |
A. Definition- self-propagating wave of electrical disturbance that travels along the surface of a neuron membrane
B. Mechanism 1. at rest, the neuron's membrane is slightly positive on the outside- polarized- from a slight excess of NA sodium ions 2. a stimulus trigers the opening of sodium channels in the plasma membrane of the neuron 3. Inward movement of sodium depolarizes the membrane by making the inside more positive than the outside at the stimulated point 4. the stimulated section of membrane immediatley repolarizes, but by that time the depolarization has already triggered the next section of membrane to depolarize, thus propagating a wave of electrical disturbances all the way down the membrane |
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The synapse |
1. Definition- the place where impulses are transmitted from one neuron to another
2. Synapse made of three structures--synaptic knob, snaptic cleft, and plasma membrane
3. Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron, opening ion channels and thereby stimulating impulse conduction by the membrane
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