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26 Cards in this Set
- Front
- Back
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motor neurons (list all 3)
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-efferent nature
-exit the CNS to body part - activate muscular or glandular response |
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sensory neurons
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-afferent nature
-identified by Roman numeral and lower case letter (type 1a, II, III, or IV fiber) |
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alpha motor neurons (list all 3)
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-high conduction velocities
-innervate majority of skeletal muscles (extrafusal musclefibers) -active prime movers of motor act |
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gamma motor neurons (list all 3)
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-slower velocity
-innervate intrafusal muscle fibers within muscle spindle -responsible for maintaining muscle tone and muscle readiness for motor act |
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cell gradients
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-established between inside and outside cell
-ions have a tendency to flow to equalize "pressure" -pumps move to increase gradient |
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electrochemical gradient
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-using electrical charge and molecular density rather than gravity pulling on water
-ions acquire either a positive or negative charge whereas positive ions will repel or other positive ions |
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concentration gradient
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molecules tend to move from area of higher concentration to lower concentration
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electroencephalography (EEG)
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sum of much neural activity within the brain produced by 'generators' and traces ion movements
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auditory brainstem response testing (ABR)
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audiologist records electrical activity of neurons to determine whether auditory pathway is intact and presents a stimulus and measures electrical emanations from the brain stem area
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passive transport
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no energy to move ions across barrier and gradient is established by inequalities on 2 sides of membrane
-voltage sensitive proteins serve as gatekeepers and open when they receive adequate stimulation |
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active transport
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energy is expended to accomplish this
-ion pumps move Na and K against gradient in form of ATP |
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NaK pump
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operates continuously moving 3 Na+ ions our for ever 2 K+ ions in
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Quiescent neuron
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intracellular space- negative
extracellular space- positive |
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neuron "fires" #1
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-critical threshold of stimulation is reaches (-55mV) and Na+ gates open so Na+ ions flood into intracellular space depolarizing it and raising the intracellular potential to +30 mV
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neuron "fires" #2
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Na+ gates open and Na+ is propelled into the cell by its concentration and electrostatic gradients so the membrane potential goes positive
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neuron "fires" #3
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K+ gates open and K+ is propelled out of the cell by its concentration and electrostatic gradients so the membrane potential drops rapidly
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neuron "fires" #4
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K+ gates close and NaK pump helps restore resting membrane potential
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absolute refractory period
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time during which cell membrane cannot be stimulated to depolarize and no amount of stimulation will cause it to depolarize again
K channel opens, K+ flows out and Na+ gates close and become inactivation NaK pumps increase intracellular concentration of K+ ions |
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relative refractory period
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after absolute refractory period
period during which membrane may be stimulated to excitation again but needs a greater than typical amount of stimulation (-80 mV will need more than rmp at -70mV) |
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ion concentrations during AP
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1- RMP -70 mV
2- stimulation occurs 3- depolarization occurs +30mV 4- negativity is greater than -70mV after potential 5- NaK pump restores rmp |
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propagation
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refers to the spreading effect of wave action in a wave of depolarization
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saltatory ('leaping') conduction
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propagating AP is passed from node to node= leaping
impulse reaches terminal point on axon and neurotransmitters are released into the synaptic cleft at 100 microseconds activates receptor proteins on postsynaptic neuron |
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excitatory vs. inhibitory
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excitatory effects- increase probability that neuron will depolarize EPSP
inhibitory effect- decrease probability that neuron will depolarize IPSP - causes hyperpolarization - found on soma |
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EPSP
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- sum of depolarizations will reach critical threshold and AP will be generated
- "voting" by neurons - "majority wins" and AP results - each neuron "votes" in favor of AP |
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spatial summation
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(space)
some neurons require near-simulataneous synaptic activations represents many points of contact arrayed over surface of post-synaptic neuron single impulse fails but lots of impulses created AP |
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temporal summation
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(time)
two or more closely successive impulses arrive at same-ish time |
