Fichas
Lab 2 Excitable Cell Membranes
Fichas del conjunto (37)
- 1voltage difference across the cell membrane at restresting membrane potential difference (resting potential)
- 2Higher K concentration is locatedICF (intracellular fluid)
- 3Higher Na concentration is locatedECF (extracellular fluid)
- 4resting membrane potential difference is usually ranges from-40 to -80 mV
- 5steps in excitable cellstimulus
graded potential
action potential
exocytosis of ACh from axon terminal - 6depolarization of soma and dendrites via influx of Nagraded potential
- 7gated Na channels lining the soma and dendrites that respond to stimulusmembrane receptors
- 8examples of things that stimulate membrane receptorsACh, other chemical ligand, mechanical force on cell membrane
- 9strength of graded potential is determined bythe strength of the stimulus
- 10strength of graded potential is affected by1. number of membrane receptors opened
2. length of time membrane receptors stay open
3. amount of Na allowed to influx - 11accumulation of Na from multiple graded potentialssummation, graded potential can summate
- 12no distinct ____________ in soma, takes time for Na to dissipate or be pumped back out after influx,repolarization process
- 13can have multiple _________ from single graded potential and/or summationaction potentials
- 14from multiple graded potentials over short period of time from the same origintemporal summation (separated by time)
- 15from multiple graded potentials arriving at about the same time from different originsspatial summation (separated by space)
- 16depolarization along length of axonaction potential
- 17voltage required to initialte action potentialthreshold
- 18connection between soma and axonaxon hillock
- 19opens at -55 mV, allows influx of Na from the ECF causing _________Voltage gated Na channel
activation gate, depolarization - 20closes at +30 mV, does not respond to voltage again after closing (under normal circumstances) takes time to resetVoltage gated Na channel
inactivation gate - 21channel starts opening at -55mV, allows efflux of K from ICF causing ________ eventually leading to ____________Voltage gated K channel
repolarization
hyperpolarization - 22only has an activation gate, slower to open, timed to be open when cell reaches +30mVvoltage gated K channel
- 23"all or nothing" due to nature of the channelsaction potential
- 24TF: can have a gradient potential without an action potentiatrue
- 25time during which another action potential cannot be initiatedabsolute refractory period
- 26Absolute refractory period starts at ________ when voltage gated ____ opensthreshold
Na - 27Absolute refractory period continues while ________ of voltage gated Na channel is ______inactivation gate
closed - 28keeps action potentials as separate, distinct depolarizations rahter than allowing axon to depolarize for extended period of timeabsolute refractory period
- 29time during which it is more difficult than normal to initiate an action potentialrelative refractory period
- 30during the relative refractory period the cell is __________ so it takes a greater amount of Na from the soma to push the axon hillock to thresholdhyperpolarized
- 31frequency or number of action potential codes for strength of signal or strength of stimulusfrequency coding
- 32transduction rate is affected byaxon diameter
myelination - 33walls cause resistance to flow, more distance from walls equals faster rate, therefore larger axons allow for faster transductionaxon diameter
- 34prevents ion leakagemyelination
- 35if Na leaks back out along the axon...Na inside the axon decreases, the diffusion rate decreases and transduction decreases
- 36With myelination...fewer gated channels are involved (Na diffuses through myelin covered sections, less Na required to be moved for process, more efficient)
fast pain (myelinated)
slow pain (non-myelinated) - 37nerve segment is bundle of axons, generally not possible to seperate a single one to be tested (except for squid giant axon) the sum of action potentials travelling on parallel axons at the same time, will vary in strength as number of axons depolarizing at one time changescompound action potential (artificial)
Información
- Descripción
- Human Physiology Fichas sobre Lab 2 Excitable Cell Membranes, creado por Erika Harkness el 23/06/2015.
- Creado por
- Erika Harkness
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