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Functions of nervous system (5)
- Initiate/reguate movement of body parts
- regulate secretions of glands
- gather information about external/internal environment
- maintain an appropriate state of consciousness
- stimulate thirst, hunger, fear, rage and sexual behaviors appropriate for survival
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3 basic functions of nervous system
- sensation (monitors change/events inside and out--stimuli and receptors)
- integration (processing and interpretation of sensory info to determine response)
- Reaction (motor output, activation of muscles or glands)
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stimuli
changes inside or outside the body monitored by nervous receptors
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receptors
usually dendrites, the cells of the nervous system that monitor stimuli
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nervous vs. endocrine system
- similarities: both monitor stimuli and reast so as to maintain homeostasis
- differences: NS is rapid and fast-acting, and the effects do not always perservere
- ES acts slower via blood-borne chemical signals (hormones) and the effects are longer-lasting
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Order of nervous function
- Sensory (afferent) division -- inputs sensation
- Peripheral nervous system
- (central nervous system) -- brain and spinal cord
- Motor (efferent) division
- .....Somatic nervous system (voluntary, skeletal)
- .....Autonomic nervous system (involuntary--cardiac, smooth, gland)
- ..........Sympathetic (fight or flight)
- ..........Parasympathetic (slow and steady, homeostastis)
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Impulse classification in nervous system
- Sensory (afferent) system (toward CNS)
- Integrating function (all inside CNS)
- Motor (efferent) system (away from CNS)
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afferent
sensory--toward CNS. Body outside CNS.
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efferent
- motor, away from CNS. Carry info from CNS to peripheral muscle, glands and/or other neurons. Body inside CNS
- Comes in 2 parts (somatic, automatic)
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somatic motor neuron
1 efferent neuron, away from CNS
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autonomic motor neuron
2 neurons (pre-ganglionic, post-ganglionic)
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neuroglia
- helper-cells to nerves, structurally and functionally maintain.
- maintain myelin sheath, repair damage, metabolic support.
- 50x more neuroglia than nerves. Can divide
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Neuron
functional unit of the nervous system. Initates and conducts. Needs lots of oxygen, can't reproduce. Can regerate if the body is okay.
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3 parts of a neuron
- Cell body (soma or perikaryon)
- dendrites
- axons
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Neuron cell body or soma
control center of neuron. Synthesizes enzymes and other molecules essential to normal function. Contain Nissl bodies (rough ER), golgi bodies, mitochondria, but no mitosis stuff.
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Nissl bodies
Rough ER in neuron cell body
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Nuclei
groups of nerve bodies in the CNS (same as ganglia in PNS)
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Ganglia
groups of nerve cell bodies outside brain in PNS (same as nuclei in CNS)
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Nerve process
an arm-like extension emanating from every neuron. 2 kinds in a neuron: Axon and dendrite.
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Dendrites
recieve stimuli, or impulses, from other neurons and conduct this stimulation to cell body. Ends of dendrites are receptors (modified). Lots of branches into cell body.
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Axon
- conducts nerve impulses away from the cell body toward another neuron of an effector (single, long process, has neurofibrils but no nissl bodies).
- Long process goes to neuron or effector organs (DO something)
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Axon hillock
"neck" leading into axon
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Telodendrion synaptic knobs
terminal bulb of axon tendrils
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axolemma
axon plasma membrane
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Tracts or Fasciculi
Bundles of nerve processes in CNS (like nerves, in PNS)
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Nerves
Bundle of nerve processes in PNS (like tracts or fasciculi in CNS)
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Myelination
Function is to increase speed of impulse conduction along the axon and to insulate the nerve process. Neuroglia cell wrapped around axon or dendrite many times--myelinate fiber.
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Oligodendrocytes
myelin sheath in CNS (like Schwann cells in PNS)
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Schwann cells
myelin sheath in PNS (like oligodendrocytes in CNS)
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