Term
| Henneman Size Principle (2) |
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Definition
| Motor units are activated from smallest to largest (leg muscles) |
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Definition
| incapable of fine motor control but are able to create larger amounts of tension |
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Definition
| allow for very fine muscle control (Eye movements) |
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Term
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Definition
| motor neuron and all the muscle fibers it innervates |
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Term
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Definition
| made of Myosin (thick) and Actin (thin) fillaments in muscle cells |
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Term
| Lab recruitment of muscles (2) |
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Definition
| direct stimulation of sciatic nerve causes the recruitment of motor neurons from largest to smallest, due to larger neurons having a lower threshold to direct electrical stimulation (lower resistance) |
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Term
| Neuromuscular Junction (2) |
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Definition
| area where the motor neuron synapses with the muscle fiber |
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Term
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Definition
Depolarization of neuron on muscle releases ACh in the synaptic cleft
binds to nicotinic ACh receptors (nAChR) causing them to open.
nAChR are ligand gated cation channels (not muscarinic ACh receptors) |
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Term
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Definition
allow depolarization to pass plasma membrane into the middle of the muscle fiber
propagate depolarizations to the SR |
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Term
| Sarcoplasmic Reticulum (2) |
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Definition
| source of Ca2+ to initiate muscle contraction |
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Term
| Ryanodine Receptors (RyR) (2) |
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Definition
allow the efflux of Ca2+ from the SR into the cytoplasm
depolarization opens DHP receptors (L type Ca2+ channels) on T-tubules causing Ryanodine receptors on SR to open |
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Term
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Definition
| increase of intracellular Ca2+ comes from efflux of Ca2+ from SR, NOT from extracellular Ca2+ influx. |
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Term
| Troponin/Myosin Complex (2) |
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Definition
| inhibits cross-bridge cycling |
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Term
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Definition
| binds with Ca2+, then changes conformation where troponin complex moves away from the myosin binding site on actin |
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Term
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Definition
| caused by a single action potential or by direct stimulation |
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Term
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Definition
| effect generated by a single neuron as a way of achieving action potential. Summation occurs when the time constant is sufficiently long and the frequency of rises in potential are high enough that a rise in potential begins before a previous one ends. The amplitude of the previous potential at the point where the second begins will algebraically summate, generating a potential that is overall larger than the individual potentials. This allows the potential to reach the threshold to generate an action potential. |
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Term
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Definition
| way of achieving action potential in a neuron which involves input from multiple cells. Spatial summation is the algebraic summation of potentials from different areas of input, usually on the dendrites. Summation of excitatory postsynaptic potentials allows the potential to reach the threshold to generate an action potential, whereas inhibitory postsynaptic potentials can prevent the cell from achieving action potential. |
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Term
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Definition
| plant alkyloid that is a competitive inhibitor of nAChR effects of competitive inhibitor can be overcome by increasing the concetnration of the agonist (ACh) |
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Term
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Definition
patterned, involuntary response to a stimulus
graded response: strength of response proportional to the stimulus |
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Term
Reflex Arc (3)
5 components |
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Definition
Stimulus/Receptor: converts stimulus as electrical signal, activating an AP in an Afferent neuron
Afferent Nerve Fibers: propagates AP to the integrator
Integrator: spinal cord or higher areas within the CNS. Activates efferent neurons.
Efferent Nerve Fibers: propagates AP from integrator to the effector structure/system
Effector/response: recieves the signal causing a response |
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Term
| Stretch/Myotatic Reflex (3) |
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Definition
reflex cuased by the stretching of muscle spindles
1. tap stretches muscle fibers
2. 1A afferents
3. Dorsal Root of spinal cord integrates signal
4. 1A axons make monosynaptic connection to a-motor neurons (efferent)
5. activated a-motor neurons cause contraction of muscle |
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Term
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Definition
measures length and rate of stretch of muscle
modified muscle fiber (intrafusal muscle fiber)
muslce fibers called extrafusal "
encircled by branches from 1A afferent nerve fiber |
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Term
Hoffman Reflex (3)
H-Reflex |
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Definition
Electrically induced monosynaptic reflex
Direct stimulation of tibial nerve (has both 1A afferent and a-motor neurons),
bypassing the muscle spindle
1. direct stimulation of tibial nerve
2. 1A afferents
3. Dorsal Root (spinal cord) integrates signal
4. a-motor neurons stimulation from monosynaptic connection 1A axons
5. contraction of muscle |
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Term
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Definition
| caused by the 1A afferent activation of hte H-reflex arc |
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Term
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Definition
| Caused by direct activation of a-motor neurons |
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Term
| Order of H-wave and M-wave (3) |
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Definition
1A afferent fibers have LARGER diameter than a-motor neurons
larger diameter means less resistance, and activation at lower voltages
@ lower voltages, H-waves seen first
@ higher voltages, M-waves become visible
a-motor neurons activated directly are not the same ones that are activated by the H-reflex
even if the H-reflex tried to stimulate the a-motor neurons directly activated, they would be in their refractory period, unable to fire an AP
As voltage increased, recruiting more a-motor neurons directly
M-wave increases in amplitude
H-wave decreases and eventually disappears |
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Term
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Definition
| time period between stimulation and response |
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Term
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Definition
Inhibitory interneuron
branch of a-MN near the cell body synapse and inhibit the a-MNs
Uses glycine as inhibitory neurotransmitter
Recurrent inhibition |
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Term
| Recurrent Inhibittion (3) |
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Definition
single interneuronal synaptic self-inhibition
Renshaw Cell |
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