Neural Tissue
... If the cell membrane were freely permeable to K+ but impermeable to other positively charged ions, potassium ions would continue to leave the cell until the electrical gradient was as strong as the chemical gradient. Equilibrium would occur around -90 mV. If the cell membrane were freely permeab ...
... If the cell membrane were freely permeable to K+ but impermeable to other positively charged ions, potassium ions would continue to leave the cell until the electrical gradient was as strong as the chemical gradient. Equilibrium would occur around -90 mV. If the cell membrane were freely permeab ...
ion channels in plants - Physiological Reviews
... sodium ions entering the nerve cell were associated with the initial depolarization phase and potassium ion efflux to the subsequent repolarization (51, 134, 135). However, Nitella and Chara, living in (low saline) fresh water, instead release chloride for membrane depolarization and K⫹ to recover t ...
... sodium ions entering the nerve cell were associated with the initial depolarization phase and potassium ion efflux to the subsequent repolarization (51, 134, 135). However, Nitella and Chara, living in (low saline) fresh water, instead release chloride for membrane depolarization and K⫹ to recover t ...
ion channels in plants
... sodium ions entering the nerve cell were associated with the initial depolarization phase and potassium ion efflux to the subsequent repolarization (51, 134, 135). However, Nitella and Chara, living in (low saline) fresh water, instead release chloride for membrane depolarization and K⫹ to recover t ...
... sodium ions entering the nerve cell were associated with the initial depolarization phase and potassium ion efflux to the subsequent repolarization (51, 134, 135). However, Nitella and Chara, living in (low saline) fresh water, instead release chloride for membrane depolarization and K⫹ to recover t ...
Mechanisms of excitability in the central and peripheral nervous
... seizures (convulsions) over time. Seizures are characterized by increased and highly synchronized neural activity. Therefore, mechanisms that regulate synchronized neural activity are crucial for the understanding of epileptogenesis. Such mechanisms must differentiate between synchronized and semi s ...
... seizures (convulsions) over time. Seizures are characterized by increased and highly synchronized neural activity. Therefore, mechanisms that regulate synchronized neural activity are crucial for the understanding of epileptogenesis. Such mechanisms must differentiate between synchronized and semi s ...
Glia Engulf Degenerating Axons during Developmental Axon Pruning
... Developmental axon pruning is widely used in constructing the nervous system. Accordingly, diverse mechanisms are likely employed for various forms of axon pruning [1–7]. In the Drosophila mushroom bodies (MB), ␥ neurons initially extend axon branches into both the dorsal and medial MB axon lobes in ...
... Developmental axon pruning is widely used in constructing the nervous system. Accordingly, diverse mechanisms are likely employed for various forms of axon pruning [1–7]. In the Drosophila mushroom bodies (MB), ␥ neurons initially extend axon branches into both the dorsal and medial MB axon lobes in ...
Neuronal Activity and Ion Homeostasis in the Hypoxic Brain
... restored to a resting value when disturbed, but increases fast when a threshold value is crossed. Their model shows how spreading depolarization waves originate from tissue close to the ischemic core, depleting the metabolic stores in the tissue in the penumbra, thereby increasing the infarct size. ...
... restored to a resting value when disturbed, but increases fast when a threshold value is crossed. Their model shows how spreading depolarization waves originate from tissue close to the ischemic core, depleting the metabolic stores in the tissue in the penumbra, thereby increasing the infarct size. ...
Physiological and Morphological Analysis of Synaptic Transmission
... that transmitter release from the inhibitor occurs by way of graded membrane potential changes in addition to the release caused by the presynaptic impulses. The lowest level of presynaptic current injection which produced an observable hyperpolarization in VE-4 was usually around 0.25 nA. This lowe ...
... that transmitter release from the inhibitor occurs by way of graded membrane potential changes in addition to the release caused by the presynaptic impulses. The lowest level of presynaptic current injection which produced an observable hyperpolarization in VE-4 was usually around 0.25 nA. This lowe ...
Alterations in Synaptic Strength Preceding Axon Withdrawal
... He repeatedly stimulated the vagus nerve of a frog heart, which caused a slowing of the heartbeat, and collected the artificial saline that emerged from the ventricle. When he later perfused the same heart with the fluid previously collected, the fluid alone caused the heart to slow down. Later the ...
... He repeatedly stimulated the vagus nerve of a frog heart, which caused a slowing of the heartbeat, and collected the artificial saline that emerged from the ventricle. When he later perfused the same heart with the fluid previously collected, the fluid alone caused the heart to slow down. Later the ...
1 Expression of Ion Channels in Xenopus Oocytes
... cytes. For example, the cut-open oocyte voltage-clamp was developed specifically for high resolution electrophysiological recording from oocytes and it is particularly well-suited for analyzing fast ionic and gating currents [10, 11]. There are a number of disadvantages to using oocytes for expressi ...
... cytes. For example, the cut-open oocyte voltage-clamp was developed specifically for high resolution electrophysiological recording from oocytes and it is particularly well-suited for analyzing fast ionic and gating currents [10, 11]. There are a number of disadvantages to using oocytes for expressi ...
MF07.pdf
... very close to the LDA ones, both overestimating the exact polarizability. However, the ground-state response using the VK potential shown is expected to yield polarizabilities much closer to the exact one because of the fieldcounteracting behavior. The magnitude of the exact step between two closeds ...
... very close to the LDA ones, both overestimating the exact polarizability. However, the ground-state response using the VK potential shown is expected to yield polarizabilities much closer to the exact one because of the fieldcounteracting behavior. The magnitude of the exact step between two closeds ...
Conductance-Based Model of the Voltage
... displays the individual ionic currents (bottom) during spontaneous activity of the model. Rhythmic spontaneous activities of the model are driven largely by INa. The fast upstroke of the action potential in the model is driven by INa (Fig. 1C) (Do and Bean 2003). After activation of INa, IK activate ...
... displays the individual ionic currents (bottom) during spontaneous activity of the model. Rhythmic spontaneous activities of the model are driven largely by INa. The fast upstroke of the action potential in the model is driven by INa (Fig. 1C) (Do and Bean 2003). After activation of INa, IK activate ...
Post-pubertal Emergence of Prefrontal Cortical Up
... Because neocortical pyramidal neurons undergo several changes in both morphological and physiological properties during postnatal development until PD 42 (Zhu, 2000), we interpreted the depolarizing events as resulting from critical glutamate activation in a mature cortical network. Bath-application ...
... Because neocortical pyramidal neurons undergo several changes in both morphological and physiological properties during postnatal development until PD 42 (Zhu, 2000), we interpreted the depolarizing events as resulting from critical glutamate activation in a mature cortical network. Bath-application ...
Ways of Ion Channel Gating in Plant Cells
... led to identi®cation of more than 70 plant protein kinase genes (Stone and Walker, 1995). However, the precise function of speci®c protein kinases and phosphatases during plant growth and development has been elucidated in only a few cases (Stone and Walker, 1995). POTA S S I U M C H A N N E L S Ion ...
... led to identi®cation of more than 70 plant protein kinase genes (Stone and Walker, 1995). However, the precise function of speci®c protein kinases and phosphatases during plant growth and development has been elucidated in only a few cases (Stone and Walker, 1995). POTA S S I U M C H A N N E L S Ion ...
1. Materials and Methods
... Full testing of the best and less effective action then involved 3 ‘sensory’ conditions: vision-andsound (‘V+S’), vision-only (‘V’) and sound-only (‘S’), (see Figure 1B), and during the active performance of the best, and in part of the neurons, the less effective action (‘M’), see below. To test se ...
... Full testing of the best and less effective action then involved 3 ‘sensory’ conditions: vision-andsound (‘V+S’), vision-only (‘V’) and sound-only (‘S’), (see Figure 1B), and during the active performance of the best, and in part of the neurons, the less effective action (‘M’), see below. To test se ...
Coding Rate and Duration of Vocalizations of the Frog, Xenopus laevis
... et al., 2007). Final concentrations of 30 or 60 M were obtained by applying 1 ml of concentrated 5-HT stock solution (0.6 or 1.2 mM, respectively, in saline) to the recording chamber. We found no difference in either the rate of CAPs or trill duration between the two concentrations, so fictive reco ...
... et al., 2007). Final concentrations of 30 or 60 M were obtained by applying 1 ml of concentrated 5-HT stock solution (0.6 or 1.2 mM, respectively, in saline) to the recording chamber. We found no difference in either the rate of CAPs or trill duration between the two concentrations, so fictive reco ...
Hearing, I: The Cochlea - American Journal of Neuroradiology
... transmitted via the apex of the cochlea (helicotrema) to the scala tympani and eventually dissipated at the round window (Figs 3 and 4). The flexible nature of the round window diaphragm is necessary for fluid propagation. Occlusion of the round window by otosclerotic plaques may render prosthetic s ...
... transmitted via the apex of the cochlea (helicotrema) to the scala tympani and eventually dissipated at the round window (Figs 3 and 4). The flexible nature of the round window diaphragm is necessary for fluid propagation. Occlusion of the round window by otosclerotic plaques may render prosthetic s ...
Plasma Membrane Depolarization Induced by
... and cold stress activate anion channels following a Ca21-dependent pathway (Cho and Spalding, 1996; Lewis et al., 1997). Nod factors induce increases in inward anion and time-dependent K1 currents (Kurkdjian et al., 2000), while cryptogein triggers chloride effluxes (Lebrun-Garcia et al., 1999). How ...
... and cold stress activate anion channels following a Ca21-dependent pathway (Cho and Spalding, 1996; Lewis et al., 1997). Nod factors induce increases in inward anion and time-dependent K1 currents (Kurkdjian et al., 2000), while cryptogein triggers chloride effluxes (Lebrun-Garcia et al., 1999). How ...
Zn2 Slows Down CaV3.3 Gating Kinetics: Implications for
... same neuron (Joksovic et al. 2005a; Talley et al. 1999). These include CaV3.1 (Perez-Reyes et al. 1998) and CaV3.2 (Cribbs et al. 1998) channels—which carry the classical fast inactivating T-type current (Carbone and Lux 1984; Fox et al. 1987; Kostyuk et al. 1988)—and the CaV3.3 channels (Lee et al. ...
... same neuron (Joksovic et al. 2005a; Talley et al. 1999). These include CaV3.1 (Perez-Reyes et al. 1998) and CaV3.2 (Cribbs et al. 1998) channels—which carry the classical fast inactivating T-type current (Carbone and Lux 1984; Fox et al. 1987; Kostyuk et al. 1988)—and the CaV3.3 channels (Lee et al. ...
LY-294002-inhibitable PI 3-kinase and regulation of baseline rates
... MA), and then subcultured on Transwell-Clear cluster inserts (Costar) for at least 10 days to achieve confluence and complete development of their transepithelial transport characteristics (19). The cells were fed twice a week with growth medium that was based in most cases on a mixture of equal par ...
... MA), and then subcultured on Transwell-Clear cluster inserts (Costar) for at least 10 days to achieve confluence and complete development of their transepithelial transport characteristics (19). The cells were fed twice a week with growth medium that was based in most cases on a mixture of equal par ...
The Neuronal Endomembrane System
... demonstrates the presence of sugars such as are found on glycoproteins) found that, although AR in the axon and tubular profiles near the GA in the cell body stain positive, there was no staining of RER (Quatacker, 1981). This latter finding at the very least argues against the presence of a simple ...
... demonstrates the presence of sugars such as are found on glycoproteins) found that, although AR in the axon and tubular profiles near the GA in the cell body stain positive, there was no staining of RER (Quatacker, 1981). This latter finding at the very least argues against the presence of a simple ...
9 Propagated Signaling: The Action Potential
... NERVE CELLS ARE ABLE TO carry signals over long distances because of their ability to generate an action potential—a regenerative electrical signal whose amplitude does not attenuate as it moves down the axon. In Chapter 7 we saw how an action potential arises from sequential changes in the membrane ...
... NERVE CELLS ARE ABLE TO carry signals over long distances because of their ability to generate an action potential—a regenerative electrical signal whose amplitude does not attenuate as it moves down the axon. In Chapter 7 we saw how an action potential arises from sequential changes in the membrane ...
central effects of centripetal impulses in axons of spinal ventral roots
... the negative phase of each repetitive action potential usually is not preceded by a positive deflection such as must herald the approach of an impulse from a distance. Moreover, inasmuch as the neurons frequently can be fired by the stimulation of any one of two or more peripheral motor nerves (see ...
... the negative phase of each repetitive action potential usually is not preceded by a positive deflection such as must herald the approach of an impulse from a distance. Moreover, inasmuch as the neurons frequently can be fired by the stimulation of any one of two or more peripheral motor nerves (see ...
FREE Sample Here
... Study Objective 1: SO 12.3 Describe the types of electrical signals that permit communication among neurons. Study Objective 2: SO 12.3.3 Describe the factors that maintain a resting membrane potential. Section Reference 1: Sec 12.3 Electrical Signals in Neurons 12) Na+/K+–ATPase is considered to be ...
... Study Objective 1: SO 12.3 Describe the types of electrical signals that permit communication among neurons. Study Objective 2: SO 12.3.3 Describe the factors that maintain a resting membrane potential. Section Reference 1: Sec 12.3 Electrical Signals in Neurons 12) Na+/K+–ATPase is considered to be ...
Dorsal Column Nuclei Neurons Recorded in a Brain Stem–Spinal
... firing threshold and differences in the shape of the action potentials could be distinguished. Six of the 14 neurons tested had action potentials that were followed by afterhyperpolarizations of mean amplitude at firing threshold of 13 ⫾ 1.2 mV and duration 268 ⫾ 26 ms [see Fig. 2A(ii)]. The remaini ...
... firing threshold and differences in the shape of the action potentials could be distinguished. Six of the 14 neurons tested had action potentials that were followed by afterhyperpolarizations of mean amplitude at firing threshold of 13 ⫾ 1.2 mV and duration 268 ⫾ 26 ms [see Fig. 2A(ii)]. The remaini ...
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and endocrine cells, as well as in some plant cells. In neurons, they play a central role in cell-to-cell communication. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction. In beta cells of the pancreas, they provoke release of insulin. Action potentials in neurons are also known as ""nerve impulses"" or ""spikes"", and the temporal sequence of action potentials generated by a neuron is called its ""spike train"". A neuron that emits an action potential is often said to ""fire"".Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane. These channels are shut when the membrane potential is near the resting potential of the cell, but they rapidly begin to open if the membrane potential increases to a precisely defined threshold value. When the channels open (in response to depolarization in transmembrane voltage), they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current across the cell membrane, and so on. The process proceeds explosively until all of the available ion channels are open, resulting in a large upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state. After an action potential has occurred, there is a transient negative shift, called the afterhyperpolarization or refractory period, due to additional potassium currents. This mechanism prevents an action potential from traveling back the way it just came.In animal cells, there are two primary types of action potentials. One type is generated by voltage-gated sodium channels, the other by voltage-gated calcium channels. Sodium-based action potentials usually last for under one millisecond, whereas calcium-based action potentials may last for 100 milliseconds or longer. In some types of neurons, slow calcium spikes provide the driving force for a long burst of rapidly emitted sodium spikes. In cardiac muscle cells, on the other hand, an initial fast sodium spike provides a ""primer"" to provoke the rapid onset of a calcium spike, which then produces muscle contraction.