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26 Cards in this Set
- Front
- Back
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Length constant is...
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the distance that an action potential is going to travel in a neuron.
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Length constant increases....
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As Rm increases. Because less current leaving and more staying in.
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Length constant decrease when...
2 possible ways... |
1. Cross sectional area decreases - Neuron diameter decreases(this causes internal resistance to increase)
2. Membrane resistance decreases (demyelation - Length constant decreased). |
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Capacitance increases when...
Capacitance decreases when... |
The thickness decreases (demyelnation).
The thickness increases (mylenation). |
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How does myelantion impact time constant?
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Myelnation - Decreases Time constant...(1) Increases thickness hence, decreases capacitance. (2) Increases cross sectional area hence, decreases membrane resistance.
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Capacitance equals to...
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equation...(e*Area/thickness)
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Resistance equals..
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Length*Resistivity/xsectional area
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What is a local potential?
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A local potential is unpropagated depolarization. It does not reach threshold to cause an Action potential.
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Define...
Positive phase Negative AFterpotential Positive Afterpotential |
Postive phase: Negative beyond resting membrane potential (result of open K channels)
Negative Afterpotential - Temp depolarization after positive phase. Positive Afterpotential - Hyperpolarization after negative afterpotential. |
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What are the functions of following transmitters?
TEA, TTX, Conotoxin, Saxitoxin, Tetanus Toxin, Physostigimine |
TEA - Blocks K channels
TTX - Blocks Na channel Conotoxin - Ca2+ channel Saxitoxin - Na channel Tetanus - Ach release Physostigmine - Aetylcholinestrase |
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Diffusion equals...
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(delta X)sqr/2time
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Hyperosmotic solution will cause the cell to....
Hypoosmotic solution will cause the cell to... |
Shrink
Swell |
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Describe the sequence of events when light hits Rod cells?
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Light >> Activate Rods >> Activate Gt >> Activate PDE >> Inhibit cGMP >> Close Na channels and Na conductance decreases (cell hyperpolarizes)
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What is receptor potential?
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Transmembrane potential of the sensory cell. Produced by seonsory transducer. Deploarizing event from inward current. Causes AP if threshold is reached (again, in sensory cell).
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Energy (for sound) =
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P square
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Diopter equals...
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1/f (focal length)
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Explain the transfer of Ach in the pre-synaptic vesicle?
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2ndary active transport. ATP used by proton pump to pump H in. Then a contratransport pumps H out and Ach in.
[Ach] in the vesicle is 150mM. |
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What is Myasthania Gravis
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Limited number of post-synaptic receptors.
(Achesterase inhibition for treatment) |
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What is end-plate potential?
How can it be measured? |
Potential at neuromuscular junction which gives rise to an AP. (local, can't propogate, half-way betwenn Ena and Ek)
Measured within 2mm of the axon. After 2mm, only AP is seen. |
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Give an example of a transmitter used in pre-synaptic inhibition transmission.
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GABA - Inhibitory terminal making synapse on excitatory synaptic terminal.
By opening Cl channels. |
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Describe the difference between EPP, EPSP and Generator potential.
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None.
EPP - NMJ EPSP - CNS Neural junctions Generation potential - Sensory junctions |
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What are TRPs? Give some examples.
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TRPs are Transient Receptor Potential ion channels. They are involved in sensory generator potential.
Examples - TRPV1 - Hot temp TRPM8 - Cold temp and menthol |
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Describe sequence of events in a sensory neuron.
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Stimulus produced genertor potential >> spike discharge frequncy >> resutls in the AP.
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Examples of primary active transport...
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Ptype - Na/K; K/H; Ca
Vtype - Ca and H Ftype - H+ transport in mitochondria. ADP to ATP |
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What are the effects of cAMP?
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cAMP opens chloride channels. Hence chloride leaves into lumen. Na and Water follow and this results in diarrhea.
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DHP - Dihydropyridine
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Activated L-type Ca+2 channels in the T-tubule. Initiates contraction in skeletal muscle.
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