Flashcards in Nervous Tissue CH 11 Deck (41):
1
Functions of the nervous system
1.Sensory input (PNS)
2. Integration (CNS)
3.Motor output (PNS)
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Peripheral Nervous System (PNS)
Not including the CNS (brain and spinal cord)
Consists or spinal and cranial nreves
3
PNS functional subunits
Afferent
Efferent
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Afferent Division
Sensory "carrying towards"
1. Somatic sensory fibers: convey impulses from skin, muscles and joints
2. Visceral sensory fibers: transmit from visceral organs (in ventral body cavity)
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Efferent Division
Motor "carrying away"
1.Somatic NS: voluntary, controls skeletal muscles
2. Autonomic NS: involuntary, controls heart pumping digestion ect.
6
Neuroglia (or glial cells)
6 cells that make us neurons:
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Neuroglia of the CNS
Astrocytes
Microglial
Ependymal
Oligodendrocytes
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Neuroglia of the PNS
Satellite cells
Schwann Cells
9
Astrocytes
Most abundant & versatile
Making exchanges between capillaries and neurons
Mopping up leaked K+
Recycling released neurotransmitters
10
Microglial Cells
Type of macrophage
Phagocytize microorganisms and neural debres
Janitor
11
Ependymal Cells
Line CNS cavities
Cilia helps circulate CSF
12
Oligodendrocytes
Form myelin sheaths around CNS fibers
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Satellite cells
unknown function may be similar to astrocytes
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Schwann Cells
Vital for regeneration of peripheral nerve fibers.
Form myelin sheath
Similar to oligodendrocytes
15
Dentrites
Receptive, input region
Each neuron has many dentrites
Motor neurons, off the cell body
Short, tapering, diffusley branching extentions
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Axons
Each neuron has one axon
spender process
long axon = nerve fiber
Conducting region
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Axon Hillock
cone shaped initial region of the axon
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Axon Collaterals
Extend from axon at right angles
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Axon terminals
Secretory region
knoblike distal ends of axon terminal branches
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Myelin Sheath
White, fatty fibers (protein-lipiod)
Protects, electronically insulates and increases speed on nerve impulse
Only on axons not dendrites.
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White matter
Myelinated regions of the CNS, primary fiber tracts.
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Grey matter
Unmyrlinated fibers and contains mostly nerve cell bodies.
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Nodes of Ranvier
Gaps in myelin sheath
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Neuron structural classifications
Multipolar
Bipolar
Unipolar
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Multipolar neurons
3 or more processes (1 axon the rest dendrites)
Most common
Major type in CNS
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Bipolar neurons
2 processes
(1 axon 1 dendrite)
retina and olfactory mucosa
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Unipolar neurons
Single short process
emerges from cell body
divides T-like into proximal and distal branches
Found in PNS ganglia
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Interneurons
Multipolar
lie between sensory and motor
In CNS
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Action Potential
Nerve impulse, conduction impulse that travels down the axon.
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Voltage
Potential energy generated by separated charge.
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Current
Flow of electrical charge from one point to another
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Resistance
The hindrance to charge flow provided by substance it passes through
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Ohm's Law
Current= voltage/resistance
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2 membrane ion channels
1. Chemically gated
2. Voltage gated
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Chemically gate ion channels
Open when neurotransmitter binds
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Voltage gated ion channels
Open and close in response to changes in membrane potential.
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Resting membrane potemtial
The potential difference in a resting neuron
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Generating resting membrane potential depends on:
1. Differences in K+ and Na+ concentrations in and out of the cell.
2. Differences in permeability of plasma membrane to those ions.
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Change in membrane potential can produce:
1. Graded potentials:Incoming signals over short distances
2. Action potentials: long dostance signals of axons
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Depolarization
Decrease in membrane potential
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