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80 Cards in this Set
- Front
- Back
Peripheral Nervous System
is made up of: Function: |
spinal nerves, cranial nerves, autonomic nervous system
function: carries info into and out of CNS |
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spinal nerves (also called somatic nerves)
dorsal and ventral roots |
(PNS) 31 pairs bring in sensory info and motor signals to and from the CNS
each spinal nerve has a dorsal (back) root: brings in sensory info ventral (front) root: sends motor controls out |
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cranial nerves
List 12 pairs. Sensory, motor, or both? |
(PNS) directly connected to brain's medulla
12 pairs: I. olfactory: (Sensory) smell II. optic (S) vision III. oculomotor (Motor) moves eyes IV. trochlear (M) moves eyes V. trigeminal (S,M) face/sinuses/teeth, moves jaw muscles VI. abducens (M) moves eyes VII. facial (S,M) tongue, moves facial muscles/salivary glands/tear glands VIII. vestibulochlear: (S) inner ear with auditory and balance functions IX. glosspharyngeal: (S,M) taste, moves throat muscles X. vagus: (S, M) info from internal organs (involuntary movement) XI. spinal accessory: (M) neck and shoulders XII. hypoglossal: (M) tongue |
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autonomic nervous system
sympathetic, parasympathetic |
(PNS) controls the internal organs (involuntary)
sympathetic: "fight or flight" weekday system, hearing "pop quiz" parasympathetic: "rest and digest" weekend system |
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central nervous system
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brain and spinal cord
mediates all sensory inputs and motor outputs, generates behavior |
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anatomical directions: anterior, posterior, dorsal, ventral, medial, lateral
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anterior (rostral): towards front
posterior (caudal): towards back dorsal: top ventral: bottom medial: in the middle lateral: on the outsides |
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lobes of the cerebral hemisphere
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frontal lobe: executive functions, retain long term memory
parietal lobe: spatial functions temporal lobe: primary auditory cortex, high level vision and memory occipital lobe: primary visual cortex, fine motor skills |
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outer surface of brain (CORTEX): gyri and sulci
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gyri: bumps/top parts of folds
sulci: infolds |
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corpus callosum
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2 cerebral hemisphere connected by fiber bridges. They allow communication between the right and left hemispheres
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medulla, pons, hypothalamus, thalamus, hippocampus, fornix, pituitary gland, cerebellum, superior/inferior colliculus
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be able to identify on images!
hippocampus and fornix: learning (limbic system) thalamus: all sensory info enters thalamus, where neurons send that info to the cortex hypothalamus: hunger, thirst, temperature regulation, reproduction drive...controls pituitary gland: controls almost all hormone secretion |
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meninges
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protective sheets of tissue that surround the brain and spinal cord
1. dura mater (outermost, hard) 2. arachnoid mater (spiderweb like, between dura and pia) 3. pia mater (innermost, soft) |
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cerebral spinal fluid (CSF) and ventricular system
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CSF: waterbed protections comes from middle of tube that evolved into little holes called ventricles
medium for exchange between blood vessels and brain tissue |
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choroid plexus
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lateral ventricles line with choroid plexus makes CSF in ventricles
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Ramon Y Cajal
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father of neuroscience
using Golgi stains, Cajal pieced together neural tissues to see how neurons are arranged (his drawings) |
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Camillo Golgi
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developed Golgi staining technique: visualization approach that stains axons and dendrites
stains only a few cells used to characterize the variety of cells in a region |
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Neuron doctrine
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Cajal
neurons are independent functional and physiological units in the brain (extension of the cell theory: every structure is made up of cells) |
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Reticular Theory
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(Golgi)
neurons are linked by anastomosis (continuity) |
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Light microscopy vs. electron microscopy
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resolution of the light miscoscope could not resolve this debate, because resolution was too low- could not figure it out definatively.
electron microscopy able to see a physical space between the axon terminal on one hand and the head of the spine on the other --> Cajal was right!!! |
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law of dynamic polarization
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Cajal
info flows from dendrites, through cell body, down axon |
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principle of connectional specificity
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Cajal
no cytoplasmic continuity between nerve cells they don't form random networks each cell forms specific connections making contact with some nerve cells and not others |
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axon hillock
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integrates inputs
"decides" output where action potential generates |
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axons
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usually 1 per cell
carries output from cell transports chemicals from cell body to terminals transmits electrical impulses to terminals (speed determined by size, myelin coating) |
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dendrites
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many per cell
receives input signals no myelin |
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axon terminals
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many per cell
output transmitted to other cells |
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3 common types of neurons
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1. monopolar neurons: transmits touch info from body to spinal cord; one axon branches 2 directions
2. bipolar neuron: common in sensory systems; one dendrite one axon 3. multipolar neuron: most common in cortex; many dendrites one axon |
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Nissl stains
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see density of cell bodies in particular regions (ex. we see big cell bodies in motor cortex bc they need to go the distance down long axons)
can also stain for neurotransmitters |
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cytoarchitectonics
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study of cell body cytoarchitecture in the cortex (using Nissl stains)
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chemoarchitectonics
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stains of neurotransmitters, hormones to differentiate the brain
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myloarchitectonics
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stains the density of the fiber bundles in the cortex
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glia
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in cortex, glia outnumber neurons 10:1 (opposite in cerebellum)
Communicate with each other and with neurons Provide raw materials and chemical signals Protection and damage control Debris removal |
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4 major glia
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Astrocytes: nourish & support with nutrients (ex. increasing bloog flow in a certain cappilary), scavenge extra neurotransmitters at synapse
Microglia: multiply at injury site, seal area, remove debris Oligodendrocytes: make myelin (insulation around axons) in the CNS Schwann cells: make myelin in PNS |
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multiple scelorosis
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"many scars"
denegration of myelin trouble moving muscles |
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myelin sheath
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fatty insulation around axons that speeds conduction, protects axons
wraps around axons in layers--white matter |
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Nodes of Ranvier
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gaps between segments of myelin
axon membrane is exposed |
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What defines a brain area?
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1. Anatomical organization (cytoarchitectonics, myeloarchitectonics and chemoarchitectonics).
2. It’s Connections with other brain areas (Anatomical connections) 3. It’s Function (Physiology studies and lesion studies) |
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anterograde tracers
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label axon terminals of cell bodies that take up the tracer (staining where cell bodies went)
inject in cortex (Where do these inputs project? Inject anterograde in different cortices.) |
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retrograde tracers
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label cell bodies of the axon terminals that take up the tracer
inject in area X (What are all the inputs to area X? Inject retrograde in X) |
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anatomical tool box
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Golgi stain
Nissl Stain Chemical stain Myelin stain Anterograde tracers Retrograde tracers |
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Two types of communication happen in neurons
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electrical: within the neurons (from dendrite to axon)
chemical: between the neurons (transmission at the synapse) |
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Ions:
anions, cations |
anions: negative charged ions
cations: positively charged ions are dissolved in intracellular fluid (cytoplasm), separated from the extracellular fluid by the cell membrane |
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resting membrane potential
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-50 to -90 mV
shows negative polarity of cell's interior resting potential is a balancing act between diffusion and electrostatic pressure that drive K+ in and out of cell |
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lipid bilayer
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cell membrane is a lipid bilayer: two layers of lipid molecules within which many special proteins float
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(gated) ion channels
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ion channels: proteins that span the membrane and allow ions to pass
gated ion channels: respond to voltage changes, chemicals, mechanical actions |
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selective permeability
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allows some substances to pass but not others
potassium ions can enter/exit freely |
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diffusion
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ions flow from high to low concentration, along concentration gradient (crystal light)
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electrostatic pressure
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ions flow towards oppositely charged areas (fridge magnets)
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sodium potassium pump
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lots of negative proteins inside cell that cannot get past membrane, making inside of cell negative (and attracting outside K+)
Pump maintains resting potential It pumps three sodium ions (Na+) out for every two K+ ions pumped in. |
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equilibrium
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when inside is -60 mV
pump causes a buildup of K+ inside. but bc of permeable membrane and diffusion, K+ will leave the inside and cause buildup of negative charge inside. now, electrostatic pressure will pull K+ back inside. equilibrium when any movement of K+ into the cell (by electrostatic pressure) matched by flow of K+ out of cell (by diffusion) |
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Nernst equation
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predicts voltage needed to counterbalance diffusion force pushing an ion across membrane
This prediction is the resting membrane potential for that ion. equilibrium potential = +40 mV |
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Hodgkin and Huxley
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measured resting membrane potential of a living neuron (from giant squid axon)
They showed that the action potential was created by the movement of sodium ions into the cell through channels in the membrane |
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hyperpolarization
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interior becomes more negative/increase in membrane potential
A hyperpolarizing stimulus produces a response that passively follows the stimulus. The greater the stimulus the greater the response–the change in potential is called a graded response. |
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depolarization
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interior becomes less negative/decrease in membrane potential
A depolarizing stimulus is the same as a hyperpolarizing one, to a point..... If the membrane reaches the threshold–about –40 mV–it triggers an action potential. The membrane potential reverses and the inside of the cell becomes positive. |
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local potential
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as potential spreads, diminishes as it moves away from stimulus
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action potential
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(spike)
brief but large reversal of the membrane potential that momentarily makes inside of the membrane positive originates at the axon hillock |
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action potential threshold
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stimulus intensity just enough to trigger action potential at the axon hillock
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all or none property of action potentials
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fire at full amplitude or not at all (flushing)
opposite of graded responses |
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afterpotentials
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positive or negative change following action potential
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voltage gated Na+ channel
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open when depolarization reaches threshold (at -40 mV)
and close when membrane potential reaches +40 mV |
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voltage gated K+ channel
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open as inside of cell becomes more positive
K+ moves out and the resting potential is restored |
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refractory period
absolute refractory phase relative refractory phase |
Refractory period–only some stimuli can produce an action potential
Absolute refractory phase–no action potentials are produced Relative refractory phase–only strong stimulation can produce an action potential |
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conduction velocity
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speed of propagation of action potentials (determined by diameter of axon, thicker=faster)
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saltatory conduction
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action potentials jump from one node of Ranvier to the next because of myelinated axons
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excitatory post synaptic potential
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produces small local depolarization
pushes cell closer to threshold caused by opening Na+ channels |
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inhibitory post synaptic potential
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produces small hyperpolarization
pushes cell farther from threshold caused by opening Cl- channels |
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Charles Sherrington
spatial summation temporal summation |
spatial summation: summing of potentials that come from different axon terminals
If the overall sum–of EPSPs and IPSPs–can depolarize the cell at the axon hillock, an action potential will occur. temporal summation: summing of potentials that arrive at the axon hillock at different times The closer together in time that they arrive, the greater the summation and possibility of an action potential. |
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Loewi and Vagustoff
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chemicals are required for synaptic transmission
Stimulation of vagus nerve slowed the heart of a frog. Placing fresh heart into same solution slowed second heart without stimulation. Deduced that stimulation of vagus released chemical into solution containing original frog |
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calcium ions Ca+2 and voltage gated calcium channels
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The sequence of transmission:
1. Action potential travels down the axon to the axon terminal. 2. Voltage-gated calcium channels open and calcium ions (Ca2+) enter. 3. Ca2+ entry causes synaptic vesicles fuse with membrane and release transmitter into the synaptic cleft |
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ligands
endogenous ligands exogenous ligands |
anything that binds to a receptor-could activate or block
endogenous: neurotransmitters/hormones exogenous: drugs and toxins from outside the body |
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Acetylcholine (ACh) and its two types of receptors
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can be excitatory (open Na+, K+ channels) or inhibitory (open Cl- channels)
motor functions (heart and muscles), learning, and memory--Alzheimers Nicotinic: most are ionotropic and excitatory (Ex. muscles use nicotinic ACh receptors–paralysis can be induced with an antagonist) Muscarinic–metabotropic and can be excitatory or inhibitory |
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agonist vs. antagonist
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agonist: molecules that act like the transmitter at a receptor
antagonist: molecules that interfere/prevent action of a transmitter at its receptor |
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iontropic vs. metabotropic receptors
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iontropic receptors: open when bound by a transmitter (ligand gated ion channel) (faster than metabotropic)
metabotropic: (no direct ion channel activity) first recognizes transmitter but instead activated G proteins G proteins, or first messengers, sometimes open channels or may activate another chemical to affect ion channels. The chemical is known as the second messenger–it amplifies the effects of the G protein and may lead to changes in membrane potential. |
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degradation and reuptake
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synapses inactivated briefly:
degradation: chemical breakdown of a neurotransmitter reuptake: released transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity |
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what defines a neurotransmitter
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Exists in pre-synaptic axon terminals
Substance is released when AP reach terminals Specific receptors recognize the substance Application of the substance produces changes in postsynaptic potential Blocking release of the substance prevents nerve impulses |
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glutamate
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major excitatory neutransmitter
uses AMPA and NMDA receptors (all ionotropic) There are also metabotropic glutamate receptors as well |
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GABA and glycine
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major inhibitory neurotransmitters
GABA A–ionotropic, producing fast, inhibitory effects via a Cl- channel (ALCOHOL) |
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dopamine
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found in
mesostriatal pathway: originates in the midbrain, specifically the substantia nigra, and innervates the striatum important in motor control and neuronal loss (separate from reward system) (parkinson's) mesolimbocortical pathway (ventral tegmental area VTA): originates in midbrain, projects to limbic system and cortex (involved with reward, reinforcement learning) (schizophrenia, addiction) |
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serotonin
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found in raphe nucleus
sleep, mood, sexual behavior, and anxiety Prozac increases serotonin |
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drugs
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act via neurotransmitter systems
many drugs are exogenous ligands can be agonists or antagonists can mess with your receptors |
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binding affinity and efficacy
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binding affinity: chemical attraction between a ligand and a receptor
efficacy (or intrinsic activity): ability of a bound ligand to activate the receptor |
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limbic system
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involved in emotion and learning
amygdala (almond shaped head of seahorse), hippocampus, fornix (tail of the seahorse) |