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The two categories of the nervous systems cells
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Neurons, or ______ cells, are ______. Neurons generate and transmit electrical signals called ______ _______
- nerve cells are excitable
- action potentials
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Glia
aka glial cells, provide support and maintain extracellular environment
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Nerve
a bundle of axons from different neuorns
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The three structural classifications of neurons
- multipolar
- bipolar
- unipolar
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multipolar
- possess more than two processes
- numerous dendrites and one axon
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Bipolar
- possess two processes
- rare
- found in some special sensory organs
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Unipolar
- aka pseudounipolar
- possess one short single process
- start as bipolar neurons during development
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Multipolar neurons have many processes that extend from the ______ _____; all are ______ except for a single ____.
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Bipolar neurons have two processes that extend from the ____ _____. One is a fused _______ while the other is an _____.
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Unipolar neurons have one process that forms _______ & ______ processes. Together both comprise an _____.
- peripheral & central
- axon
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The most abundant neuron in the body is ______. Where is it also the major neuron type?
- Multipolar
- Major neuron type of the CNS
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The bipolar neuron is _____, and found in special sensory organs. Name 4
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The unipolar neuron is mainly found in the ____. Common only in _____ ____ ____ of the spinal cord and _______ ______ of cranial nerves
- PNS
- dorsal root ganglia
- sensory ganglia
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Name two ways neurons alter membrane potentials
- Electrical synapse
- Gated ion channels
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Three types of gated ion channels
- voltage gated channels
- chemically gated channels
- mechanically gated channels
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What are the four major ions in neurons
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Membrane potential
the electrical potential/ charge difference across the membrane
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Resting membrane potential
the membrane potential of a resting neuron
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An action potential or ______ ______ is a rapid large change in the _____ ______.
- nerve impulse
- membrane potential
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Action potentials are generated by ______ & _______ of ___ ______
- opening & closing
- ion channels
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Graded membrane potentials are changes from the ______ _______
resting potentials
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Graded potentials are a means of ______ input. The membrane can respond proportionally to _______ or _______.
- integrating
- depolarization
- hyperpolarization
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EPSP
IPSP
- excitatory postsynaptic potential
- inhibitory postsynaptic potential
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Electrochemical gradient
The force/gradient created by concentration gradient and the voltage difference (electrical gradient) of the membrane
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What decides the direction and size of ion movement
electrochemical gradient
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If a membrane were permeable to only K+ then K+ would diffuse down its _______ ______ until the _____ ______ across the membrane countered diffusion. The _____ _____ that counters net diffusion of K+ is called the ___ _______ ______. **Switch K+ with Na+ for this card occasionally.
- concentration gradient
- electrical potential
- electrical potential
- K+ equilibrium potential (Ek)
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Also called the equilibrium potential
nernst potential
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Potassium channels are open during the ______ _____ phase and are highly ______ to K+ ions
- resting membrane
- permeable
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K+ ions diffuse out of the cell along the _______ ______ and leave ______ _____ behind in the cell
- concentration gradient
- negative charges
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K+ ions diffuse back into the cell because?
Because of the negative electrical potential
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Driving force equation
driving force = (Vm-Eion)
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The sign of the driving force indicates the direction of _____ ____
ionic flow
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If the driving force of Na+ is -70mV minus +55mV=-125mV, then we will have _____ _____ of _____ _____. So Na+ will _____ the cell
- inward movement
- positive current
- enter the cell
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If Driving force = +75 mV (MP) minus +55mV (ENa+) Driving force = +15mV for Na+, then there will be _____ _____ of ______ _____. Therefore, Na+ will ____ the cell.
- outward movement
- positive current
- leave
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If Driving force = -70mV (RMP) minus -90mV (EK+), the Driving force = +20mV, there will be ______ _____ of ______ ____. Therefore, positively charged K+ will ____ the cell.
- outward movement
- positive current
- leave
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If Driving force = +55 mV (MP) minus -90mV (EK+) then Driving force = +145mV there will be ______ ______ of ______ _____. Therefore, K+ will _____ the cell.
- outward movement
- positive current
- leave
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If Driving force = -95 mV (MP) minus -90mV (EK+) has a Driving force = -5mV, there will be _____ _____ of ______ _____. Therefore K+ will ____ the cell
- inward movement
- positive current
- enter
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If Driving force = -70mV (RMP) minus -60mV (ECl-) has a Driving force = -10mV, there will be _____ _____ of _____ ____. Therefore, _______ charged Cl-will _____ the cell
- inward movement
- positive current
- negatively
- leave
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Driving force = -55 mV (MP) minus -60mV (ECl-) has a Driving force = +5 mV, there will be ______ ______ of _______ ______. Therefore, C- will ____ the cell.
- outward movement
- positivie current
- enter
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Biological membranes are selectively permeable meaning:
they allow some substances to pass, while others are restricted
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Depolarization phase
- Na+ channels open
- K+ channels closed
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Repolarizing phase
- Na+ channels close
- K+ channels open
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Undershoot phase
- Na+ channels closed
- K+ channels still open
- gates haven't responded to repolarization
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_____-_____ ____ channels cannot open open during the refractory period
Voltage-gated Na+ channels
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The 2 gates of Na+ channels
- activation gate
- inactivation gate
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activation gate
closed at rest but opens quickly at threshold
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inactivation gate
- open at rest and closes at threshold
- responds more slowly
- opens 1-2 milliseconds later than the activation gate closes
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The neuromuscular junction is a chemical synapse between ______ _____ & ______ _____ cells.
- motor neurons
- skeletal muscle cells
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The motor neuron releases _______ from its axon terminals
acetylcholine
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The postsynaptic membrane of the muscle cell is the _____ ____ _____
motor end plate
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Endplate potentials (EPPs)
Voltages due to synaptic transmission and measured in the muscle
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Main neurotransmitters in the CNS
- ACh
- Glutamate
- Glycine &GABA
- Monoamines
- Peptides
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Acetlycholine is found in _____ _____ & the ____
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Glutamate is an ______ ____ ____ while glyicine and GABA are _____ ____ _____
- excitatory amino acid
- inhibitory amino acids
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Glutamate receptors are divided into classes because they can be ______ by other _____.
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Three ionotropic glutamate receptors
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Glutamate is _____ and will result in _______. But the ______ of different receptors varies significantly.
- excitatory
- depolarization
- timing
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AMPA receptors allow
rapid influx of Na+
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NMDA receptors first require a ____ ______ through other _____, they allow:
- slight depolarization
- receptors
- slower influx of Na+ & Ca++
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Neurotransmitters are cleared from the _____ after release in order to stop their action in 3 ways. State them
Cleft
- diffusion
- reuptake by adjacent cells
- enzymes present in the cleft may destroy them
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Give an example of how neurotransmitters are stopped
Acetylcholinesterase acting on acetylcholine
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The postsynaptic cell must sum the ______ & ____ input. ______ occurs at the axon hillock.
- excitatory & inhibitory input
- summation
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______ ______ adds up messages at different synaptic sites. ______ _____ adds up potentials generated at the same site, over time.
- Spatial summation
- Temporal summation
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Drugs treat the nervous system by ______ ______ ______.
modulating synaptic interactions
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Agonists _____ or ______ the effect of a neurotransmitter. Antagonists _____ the actions of a _______.
- mimic or potentiate
- block
- neurotransmitter
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