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100 Cards in this Set
- Front
- Back
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Sensory Input
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Information gathered by sensory receptorsof the nervous system about internal and external changes inside/outside thebody
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Integration
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Processing and interpretation of sensoryinput to determine response by the body
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Motor Output
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Activation of effectororgans (muscles and glands) producesa response
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Central Nervous System (CNS)
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Brain and spinal cord. Control center of nervous system
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Peripheral Nervous System (PNS)
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Cranial Nerves (12 pairs) and spinal nerves (31 pairs). Connects CNS to rest of the body.
Has 2 subdivisions-- Sensory/Afferent & Motor/Efferent |
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Sensory / Afferent Division
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A subdivision of the PNS: "Carrying Towards"
Axons convey impulses to CNS fromsensory receptors located throughout entire body |
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Motor / Efferent Division
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A subdivision of the PNS: "Carrying Away"
Transmitsimpulses from CNS to effector organs, which are the muscles and glands Has 2 subdivisions: Somatic Nervous System (SNS) & Autonomic Nervous System (ANS) |
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Somatic Nervous System (SNS)
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A subdivision of the Motor / Efferent Division
Somatic Motor = Voluntary Conducts impulses from CNS to skeletal muscles |
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Autonomic Nervous System (ANS)
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A subdivision of the Motor / Efferent Division
Visceral Motor = Involuntary Conducts impulses from CNS to cardiac & smooth muscles, and glands Has 2 subdivisions: Sympathetic & Parasympathetic |
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Sympathetic Division
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A subdivision of the Autonomic Nervous System
Mobilizes body systems during activity "Fight or Flight" |
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Parasympathetic Division
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A subdivision of the Autonomic Nervous System
Conserves energy and promotes housekeeping functions during rest "Rest and Digest" |
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Neuroglial Cells
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"Supporting” cellsthat are not electrically excitable; small cells that surround and wrapdelicate neurons
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Neuron (Nerve) Cells
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The“functional”units of the nervous system; excitable cells that carry electrical impulses(action potentials)
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Neuroglial Cells in the CNS
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- Astrocytes
- Microglial - Ependymal - Oligodendrocytes |
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Astrocytes
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A neuroglial cell in the CNS
- Most abundant, star-shaped. - Formsblood-brain barrier by covering blood capillaries - Metabolizes neurotransmitters - Providestructural support - Secretenerve growth factors |
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Microglial Cells
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A neuroglial cell in the CNS
- Smallcells found near blood vessels and neurons —monitor condition of nearby neurons - Phagocyticrole --clear away dead cells / pathogens |
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Ependymal Cells
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A neuroglial cell in the CNS
- Lines ventricles ofthe brain(cerebralcavities) & central canal ofspinal cord - Helpproduce cerebrospinalfluid(CSF) - Manyare ciliated,which helps circulate the CSF |
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Oligodendrocytes
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A neuroglial cell in the CNS
- Line up along thicker nerve fibers in CNS and wraps their processes (up to 15) tightly around these fibers - Eachforms myelin sheatharound more than one CNS axon |
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Neuroglia Cells in the PNS
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- Schwann
- Satellite |
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Satellite Cells
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A neuroglial cell in the PNS
- Flat cells surrounding neuronal cellbodies - Support neurons in the PNS ganglia - Believed to have many of same functionsas astrocytes |
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Schwann Cells
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A neuroglial cell in the PNS
- Cellsencircle all axons - Eachcell produces part ofthe myelin sheath surrounding an axon (functionally similar to oligodendrocytes) *requiresmany cells to cover entire axon |
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Myelin
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The plasma membrane of glial cells = Schwann & Oligodendrocytes
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Myelin Sheath
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Whitish, fatty (protein-lipoid) sheath that covers many nerve fibers. Protects and electrically insulates axons and increases the transmission speed of nerve impulses (action potential).
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Myelination in PNS
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Formed by Schwann cells; takes multiple cells to cover axon
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Myelin Sheath Gap (Nodes of Ranvier)
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Gapsbetween adjacent Schwann cells; Siteswhere axon collaterals can emerge
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Myelination in CNS
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Oligodendrocytesform myelin sheaths–multipleflat processes that can coil around up to 60 axons at same time. Cell bodies donot surround the axons
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White Matter
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Myelinatedprocesses. Regionsof brain and spinal cord with dense collections of myelinated fibers – usuallyfiber tracts
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Gray Matter
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Nervecell bodies, dendrites, bundles of non-myelinatedaxons and neuroglia.
- Inspinal cord, gray matter forms H-shaped inner core surrounded by whitematter - Inbrain, a thin outer shell of graymatter covers the surface & is found in clusters called nuclei inside theCNS |
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Neuron Cell Body
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AKA Soma: spherical nucleus with nucleolus; the biosynthetic center of neuron
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Ganglion
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Cluster of nerve cell bodies outside the CNS
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Dendrites
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A neuron process: Receptive (input) region of neuron, receives signals from other neurons
- Conducts impulses towards the cell body |
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Axon
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A neuron process: Conducting region of neuron (generates nerve impulses)
- Transmitsthem away from cell body |
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Axon Hillock
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The initial region of the axon arises from this cone-shaped area of the cell body
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Terminal Branches
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Branches at the end of an axon
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Axon Terminal
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The knoblike distal endings of the terminal branches; the secretory region
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Axolemma
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The neuron cell membrane
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Conducting Region of Axon
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The entire length of axon generates nerve impulses
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Secretory Region of Axon
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The axon terminals
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Sensory (Afferent) Neurons
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Transports sensory information from skin,muscles, joints, sense organs & viscera to CNS
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Motor (Efferent) Neurons
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Sends motor nerve impulses to muscles& glands
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Interneurons / Association Neurons
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Connect sensory to motor neurons; all are located within CNS = 90%of neurons in the body
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Multipolar Neuron
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Neuron with 3 ormore processes = 1axon, rest are dendrites
- Mostcommon neuron type - Majorneuron in CNS (99%) |
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Bipolar Neuron
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Neuron with 2processes = 1axon and 1 dendrite
- Extendfrom opposite sides of cell body - Rareneurons, e.g., Retina and olfactory mucosa |
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Unipolar Neuron
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Neuron with 1short process
- DividesT-like, both branches now considered axons - Distal(peripheral) process associated with sensory receptor & Proximal(central) process enters CNS |
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Chemically Gated (Ligand-gated) Channel
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Channels open when the appropriate nuerotransmitter binds
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Voltage Gated Channel
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Channels open inresponse to a change in membrane potential
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Mechanically Gated Channel
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Channels open when a membranereceptor is physically deformed
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Leakage Channels
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The cell also has Sodium and Potassium leak channels that are always open
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Concentration Gradient
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Ions move along this gradient whenthey diffuse passively from an area of their highest concentration to an areaof lower concentration
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Electrochemical Gradient
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Ions move along this gradient whenthey move towards an area having opposite electrical change
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Resting Membrane Potential
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The voltage that exists across the plasma membrane during the resting state of an excitable cell; ranges from -90 to -20 millivolts depending on cell type
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Sodium Potassium Pump
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Stabilizes the resting membrane potential by maintaining the concentration gradients (3 Na+ out and 2 K+ in)
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Graded Potentials
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A local change in membrane potential that varies directly with strength of stimulus, signal declines with distance
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Action Potentials
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Principal way neurons send signals over long distances (all or nothing)
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Depolarization
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- A decrease in membrane potential (towardzero and above)
- Inside of membrane becomes lessnegative thanresting membrane potential - Increases probability of producing anerve impulse |
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Hyperpolarization
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- An increase in membrane potential (awayfrom zero)
- Inside of cell more negative thanresting membrane potential) - Reduces probability of producing anerve impulse |
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Activation Gate
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Closed at RMP and responds todepolarization by opening
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Inactivation Gate
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Blocks the channel once it is open
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Sequence of the Action Potential
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1. Resting (-70 mV)
* Threshold (-55 mV) 2. Depolarization (+30 mV) 3. Repolarization (back to -70 mV) 4. Hyperpolarization (briefly at -90 mV) |
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Action Potential Threshold
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The weakest stimulus capable of producing a response in an excitable tissue; depolarization must reach this limit if an axon is to "fire"; often between -55 and -50 mV
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Absolute Refractory Period
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Period during which a neuron can NOTgenerate another AP
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Relative Refractory Period
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Intervalfollowing the absolute refractory period - MostNa+ channels have returned to theirresting state, someK channels still open and repolarizationoccurring
- Only a very strongstimulus can reopen Na+ channels and generate another AP |
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Propagation
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An action potential migrates down the axon towards the axon terminal
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Continuous Conduction
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Seen in unmyelinated axons; slow
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Saltatory Conduction
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Seen in myelinated axons; fast
Leaps from each Node of Ranvier which has high density of V-gated ion channels |
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Propagation Fibers
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- Type AFibers: Largest in diameter, thick myelin sheath, very brief refractory period, speeds up to 300 mph
- Type BFibers: medium diameter, lightly myelinated, speeds up to 30 mph - Type CFibers: smallest in diameter, unmyelinated, longest refractory period, speeds less than 2 mph |
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Synapse
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Functionaljunctions or points of close contact that mediates information transfer betweentwo neurons or between a neuron and an effector cell
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Axodendritic
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Synapsesbetween an axon and a dendrite
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Axosomatic
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Synapsesbetween an axon and a cell body (soma)
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Axoaxonic
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Synapsesbetween axons
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Dendrodendritic
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Synapses between dendrites
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Presynaptic Neuron
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Neuron conducting impulses toward synapse
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Postsynaptic Neuron
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Neurontransmitting electrical signal away from synapse
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Electrical Synapse
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Rare: Involvesgap junctions that contain proteins channels called connexons
- Allows ions and small molecules to rapidly flow directly from one neuron to next |
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Chemical Synapse
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Specializedto allow release and reception of chemical neurotransmitters (NT’s)
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Chemical Synapse's Information Transfer
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1. AP arrives
2. Voltage Gated Calcium Channels open 3. Calcium causes NT exocytosis 4. Reuptake 5. Enzymatic Degradation |
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Excitatory Postsynaptic Potentials(EPSPs)
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Short distance signaling; depolarization that spreads to axon hillock; moves membrane potential towards AP threshold
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Inhibitory Postsynaptic Potentials (IPSPs)
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Short distance signaling; hyperpolarization that spreads to axon hillock; moves membrane potential away from AP threshold
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Channel-Linked Receptors: Ionotropic
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Direct action- mediates fast synaptic transmission
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G Protein-Linked Receptor: Metabotropic
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Indirect action: oversees slow synaptic responses
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2nd Messengers
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Actas go-betweens to open or close ion channels, modifies (activate orinactivate) other proteins, and activates genes and induce proteinsynthesisd
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Excitatory Synapse
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Depolarizes (Na+) the postsynaptic membrane of dendrites and neuronal cell bodies
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Inhibitory Synapse
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Reducesa postsynaptic neuron’s ability to generate an AP by hyperpolarizing (K+, Cl-)
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Acetylcholine (ACh)
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Released at neuromuscular junctions
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Acetylcholinesterase (AChE)
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Degrades ACh
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Biogenic Amines
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Plays roles in emotional behavior and biological clock - Catecholamines- Indolamines |
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Catecholamines
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A Biogenic Amines:
Dopamine & Norepinephrine |
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Indolamines
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A Biogenic Amines:
Seratonin & Histamine |
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Dopamine
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"Feel Good" nuerotransmitter
Overactive = Schizophrenia Degenerative = Parkinson's Disease |
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Norepinephrine
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"Feel Good" neurotransmitter
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Seratonin
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Plays a role in sleep, appetite, and regulates mood
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Histamine
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Involved in wakefulness, appetitecontrol, learning & memory
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Amino Acid NT: Glutamate
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Important in learning & memory
Perhaps ½ of all brain synapsescommunicate via this NT |
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Amino Acid NT: Aspartate
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Important excitatory NT in spinalcord
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Amino Acid NT: GABA (gamma-aminobutyric acid)
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Primary inhibitory NT in humanbrain
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Amino Acid NT: Glycine
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Primary inhibitory NT in spinalcord
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Peptide NT: Substance P
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Mediates pain transmission
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Peptide NT: Endorphins
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Act as natural opiates, reducingperception of pain under stressful conditions
Ex: Beta Endorphin, Dynorphon, Enkephalin |
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Purine NT: ATP & ADP
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Provokes pain sensation
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Purine NT: Adenosine
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Increased NT makes us sleepy; caffeine blocks receptors
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