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78 Cards in this Set
- Front
- Back
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Neurons
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- Functional units
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Neuroglia
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- Nourish and protect nuerons
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Central Nervous System (CNS)
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- Spinal cord + brain
- Integrates/coordinates sensory and motor information |
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Peripheral Nervous System (PNS)
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- All neural tissue outside CNS
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Afferent Division
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carries sensory info from receptors to CNS
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Efferent Division
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carries motor commands from CNS to effectors
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Somatic Nervous System (SNS)
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- Controls skeletal muscle contractions
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Autonomic Nervous System (ANS)
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- Controls smooth/cardiac muscle contractions
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Sympathetic Division
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activated during times of danger
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Parasympathetic Division
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activated during times of no danger
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Cell Body (Soma)
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Contains large nucleus, cytoplasm (perikaryon) and Nissl Boddies (RER + ribosomes)
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Dendrites
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- Branched processes from soma
- Carry impulses toward soma |
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Axon
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long cytoplasmic processes with smaller branches (telodendria) ending in synaptic terminals-may branch into collaterals
- Cytoplasm (axoplasm) and membrane (axolemma) - Base is axon hillock - Carry messages |
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Neuron-Neuron
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- Typical synapse
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Neuron-Gland
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Neuroglandular synapse
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Neuron-Muscle
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Neuromuscular synapse
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Structural Classification - Anaxonic
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- Small, nondefined axon/dendrites
- Unknown function |
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Structural Classification Bipolar
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- Small, cell body in middle, two distinct processes
- Found in eyes, ears |
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Structural Classification Unipolar
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- Cell body to side, axon/dendrites are continuous
- Very long (~1 m), found in PNS |
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Structural Classification Multipolar
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- Cell body with axon, two or more dendrites
Very long (~1 m), found in CNS. |
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Sensory (Afferent) Neuron
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- Unipolar
- Axons (afferent fibers) extend between receptor and CNS |
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Motor (Efferent) Neuron - multipolar
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- Axons (efferent fibers) extend between CNS and effectors
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nterneuron (Association Neuron
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- multipolar
- Distribute info between sn and mn |
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Ependymal Cells
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line central cavity and ventriclesSecretes and moves CSF
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Astrocytes
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-large and numerous
- Cell extensions surround capillaries - Maintain blood/brain barrier |
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Microglia
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- Remove cell debris and pathogens
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Oligodendrocytes
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lipid-rich pads wrap axons to form a myelin sheath - Sheth insulates and speeds ap
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Satellite Cells
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surround cell bodies of PNS neurons.
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Schwann Cells
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-lipid-rich pads wrap axons to form a myelin sheath
- "lightly" wrap unmyelinated axon. |
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Repair in PNS
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Wallerian Degeneration
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Repair in CNS
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- Limited due to numerous neurons and scarring
Some released chemicals block axon regrowth |
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Potential Difference (pd)
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-when positive and negative charges are held apart
- Tp is pd across membrane |
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Current
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- Movement of charges to eliminate pd
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Resistance
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- Membrane restricts ion movement
- Creates resistance to current. |
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. Resting Potential (rp)
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pd at rest is –70mV-inside has [K+] and [protein-]
-outside has [Na+] and [Cl-] - K+ move thru leak channels faster than Na+ leaks in and - proteins stay in cell, so the cell inside is negative and outside is positive |
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Chemical Gradient (cg)
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- Up [K+] inside and up [Na+] outside
- Drives Na+ in and K+ out |
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Electrical Gradient (eg)
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- High - inside and high + outside
Drives Na+ inside and K+ |
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Electrochemical Gradient (ec)
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factors electrical/chemical gradients
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EC Chemical Gradient for K+
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- Drive K+ out of cell
- less than cg alone due to opposing eg |
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EC Gradient for Na+
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- Drive Na+ into cell
- greater than cg alone due to the |
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Na+/K+ Pump
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-uses ATP to pump 3 Na+s out/ 2K+s in
- along with leak channels, the pump maintains resting potential of cell |
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Leak Channels
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- Always open
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Gated (Active) Channels
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- Open and close
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Chemically Regulated
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- Open/close in response to chemicals
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Voltage Regulated
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- Open/close in response to changes in tp
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Mechanically Regulated
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- Open and close in response to physical stimulation
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Graded Potentials
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-changes in the tp that do not spread far from the point of stimulus
- Occur at the axon hillock, can lead to ap - Depolarization is a shift in rp toward a more + potential - Repolarization is the process of restoring rp - Hyperpolarization is increase in - aspect of rp |
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Action Potential (ap)
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changes in the tp that affects the entire excitable membrane - Occur at the axon
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All or None Principal
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- Need stimulus large enough to reach threshold (+10 mV) which opens voltage regulated Na+ channels
- Ap properties independent of stimulus strength |
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Generation of an Action Potential
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-stimulus causes depolarization to threshold
-Na+ channels open and Na+ ions move in (depolarization) - Na+ channels inactivated - K+ channels open and K+ ions move out (repolarization) - More K+ move out (hyperpolarization) - Na+/K+ pump and leack channels restore resting potential |
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Refractory Period
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- Time form beginning of ap until rp is stabilized
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Absolute Refractory Period
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- From when Na+ channels open until Na+ channels inactivation ends
- Membrane will not respond to second stimulus |
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Relative Refractory Period
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- From when Na+ channels regain resting condition until tp stabilizes
- Membrane responds to greater than normal second stimulus |
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Propagation
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-repeated ap along entire membrane
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Continuous Propagation
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ap spreads along unmyelinated axon
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Saltatory Propagation
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-ap spreads along myelinated axon
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Axon Diameter
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- Increase diameter decrease resistance
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Type A Fibers
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- Largest, myelinated, ap = 140m/sec
- Very important info |
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Type B Fibers
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- Smaller, myelinated ap = 18m/sec
- Less urgent info |
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Type C Fibers
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- Smallest, unmyelinated ap = 1m/sec
- Least urgent info |
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Nerve Impulse
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- Movement of ap along an axon
- Moves from pre to postsynaptic cell |
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Electrical Synapse
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- Pre and postsynaptic cell have direct contact via gap junction
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Chemical Synapse
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- Pre and postsynaptic cell do not have direct contact (cleft)
- Neurotransmitter released at synapse |
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Excitatory Neurotransmitter
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Causes depolarization and prevents ap
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Inhibitory Neurotransmitter
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- Causes hyperpolarization and prevents ap
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Cholinergic Synapse
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acetylcholine (ACh) released-neuron-neuron synapses in PNS and neuromuscular junctions (NMJs)
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Cholinergic Synapse Overview
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ap arrives, synaptic knob depolarizes -Ca+ channels open, Ca+ enters
- Entry of Ca_ causes acetylcholine release into synapse which binds receptors of post synaptic membrane - Post synaptic membrane depolarizes - Ach-esterase digests ACh |
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Other Neurotransmitters
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- Result in changes in postsynaptic cell membrane permeability
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Norepinephrine (Noradrenaline)
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- Released at adrenergic synapses in CNS and ANS affecting attention, body temp
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Dopamine
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- Released in CNS with inhibitory role in control of precise movement
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Serotonin
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- Released in CNS with effects on emotions and attention states
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Gamma-aminobutyric Acid (GABA)
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- Released at CNS with effect of reducing anxiety
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Neuromodulators
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- Affect neurotransmitter release or postsynaptic cell response
- Peptide opioids for pain control |
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Postsynaptic Potentials
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- Integration process at axon hillock which determines ap generation
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Excitatory Postsynaptic Potential (EPSP
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- Graded potential at postsynaptic membrane in response to nt
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Inhibitory Postsynaptic Potential (IPSP)
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- Graded hyperpolarization at postsyn membrane
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Summation
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potentials at membrane - Temporal (add stimuli in quick succession) of Spacial (simultaneous stimuli have cumulative effect)
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Facilitation
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- Bringing neuron tp closer to threshold
- Due to summation of EPSP's or drugs |
