Lecture 4
... Resting Potential A. Vrest 1. represents potential difference at non-excited state -30 to -100mV depending on cell type 2. not all ion species may have an ion channel 3. there is an unequal distribution of ions due to active pumping mechanisms - contributes to Donnan equilibrium - creates chemical ...
... Resting Potential A. Vrest 1. represents potential difference at non-excited state -30 to -100mV depending on cell type 2. not all ion species may have an ion channel 3. there is an unequal distribution of ions due to active pumping mechanisms - contributes to Donnan equilibrium - creates chemical ...
Nervous System Part 1
... Voltage-gated Na+ and K+ channels open at the approximately the same threshold voltage… K+ channels are just much more slower at opening wide and closing completely than Na+ channels. ...
... Voltage-gated Na+ and K+ channels open at the approximately the same threshold voltage… K+ channels are just much more slower at opening wide and closing completely than Na+ channels. ...
AP – All or nothing
... • Results in much faster propagation of the nerve impulse than is possible in unmyelinated ...
... • Results in much faster propagation of the nerve impulse than is possible in unmyelinated ...
Chapter 2: Biopsychology
... travels along an axon at a constant strength, no matter how far it must travel. It is slower then a straight electrical impulse, but has the advantage of maintaining it’s strength no matter how far it must travel. ...
... travels along an axon at a constant strength, no matter how far it must travel. It is slower then a straight electrical impulse, but has the advantage of maintaining it’s strength no matter how far it must travel. ...
The Nervous System: 1. Basics
... •! Voltage-gated potassium channels open –! K+ flows out of cell •! Loss of positive ions restores electronegativity of cytoplasm –! Na-channels close •! Cell interior ---> very negative (-90 mV) –! This patch of membrane is refractory to further stimulation for some time •! Ion imbalance triggers v ...
... •! Voltage-gated potassium channels open –! K+ flows out of cell •! Loss of positive ions restores electronegativity of cytoplasm –! Na-channels close •! Cell interior ---> very negative (-90 mV) –! This patch of membrane is refractory to further stimulation for some time •! Ion imbalance triggers v ...
Ch 8 Neurons and Network properties part-1
... Graded potentials decrease in strength as they spread out from the point of origin but may bring about an action potential. ...
... Graded potentials decrease in strength as they spread out from the point of origin but may bring about an action potential. ...
Ch 48 Notes - FacStaff Home Page for CBU
... Graded potentials are changes in polarization where the magnitude of the change varies with the strength of the stimulus ...
... Graded potentials are changes in polarization where the magnitude of the change varies with the strength of the stimulus ...
Nervous Systems
... The anatomy of a neuron. The mechanisms of impulse transmission in a neuron. The process that leads to release of neurotransmitters, and what happens at the synapse. ...
... The anatomy of a neuron. The mechanisms of impulse transmission in a neuron. The process that leads to release of neurotransmitters, and what happens at the synapse. ...
Neurones & the Action Potential
... Between the sheaths are the Nodes of Ranvier, where sodium channels are concentrated. Action potentials jump from one to the next. This is called SALTATORY CONDUCTION ...
... Between the sheaths are the Nodes of Ranvier, where sodium channels are concentrated. Action potentials jump from one to the next. This is called SALTATORY CONDUCTION ...
The vocabulary of nerve cells
... change in frequency depends on the constancy of firing of the signaling neuron (most neurons fire constantly). The absolute refractory period governs the maximum frequency. The range in frequency between these two factors governs the range of intensity of stimulus which can be reported. (Since an ac ...
... change in frequency depends on the constancy of firing of the signaling neuron (most neurons fire constantly). The absolute refractory period governs the maximum frequency. The range in frequency between these two factors governs the range of intensity of stimulus which can be reported. (Since an ac ...
A- A- A- K+ A - How Your Brain Works
... • Advantage: the feedback current injection allows action potentials to travel along axons for considerable distances without loss of signal. (Fresh Na+ currents make up for leakage). • Disadvantage: action potentials are “all or nothing”. They cannot transmit information by their amplitude, so grad ...
... • Advantage: the feedback current injection allows action potentials to travel along axons for considerable distances without loss of signal. (Fresh Na+ currents make up for leakage). • Disadvantage: action potentials are “all or nothing”. They cannot transmit information by their amplitude, so grad ...
Topic 21: COMMUNICATION BETWEEN CELLS
... Most ion channels are highly selective for the ion that each transports; thus, there are potassium, sodium, chloride, calcium etc channels. Also, for each ion there may be passive, voltage-gated & chemically-gated channels ( ca., voltage-gated K+channel) Excitation (fig. 48.8)- a neuron receives som ...
... Most ion channels are highly selective for the ion that each transports; thus, there are potassium, sodium, chloride, calcium etc channels. Also, for each ion there may be passive, voltage-gated & chemically-gated channels ( ca., voltage-gated K+channel) Excitation (fig. 48.8)- a neuron receives som ...
Ch.10
... potential at the axon hillock. The channels are depolarized to their threshold (5/10 mV more positive). • Sodium rushes In; causing the rising phase or spike of an action potential. • Repolarizing the membrane is due to rapid closing of the sodium channels. Potassium gates open more slowly and stay ...
... potential at the axon hillock. The channels are depolarized to their threshold (5/10 mV more positive). • Sodium rushes In; causing the rising phase or spike of an action potential. • Repolarizing the membrane is due to rapid closing of the sodium channels. Potassium gates open more slowly and stay ...
From Passive to Active Properties Significance of the Action
... experiments because these are primarily responsible for the action potential in neurons y Membrane potential is an epic never‐ending battle ...
... experiments because these are primarily responsible for the action potential in neurons y Membrane potential is an epic never‐ending battle ...
Graded Potential - wquerryeducation
... • Gated ion channels: channels that open or close & influence membrane permeability (membrane potential) ...
... • Gated ion channels: channels that open or close & influence membrane permeability (membrane potential) ...
The ion channels then use this concentration difference to transport
... boutons. Dendrites form protrusions in response to the axon terminal boutons. These protrusions, or spines, are designed to capture the neurotransmitters released by the presynaptic neuron. They have a high concentration of ligand activated channels. It is, therefore, here where synapses from two ne ...
... boutons. Dendrites form protrusions in response to the axon terminal boutons. These protrusions, or spines, are designed to capture the neurotransmitters released by the presynaptic neuron. They have a high concentration of ligand activated channels. It is, therefore, here where synapses from two ne ...
Chapter 48: Nervous System
... regenerates itself as it moves along the axon, increasing action potential as it moves down axons What effects speed of transmission? Diameter of axon Myelin sheath ...
... regenerates itself as it moves along the axon, increasing action potential as it moves down axons What effects speed of transmission? Diameter of axon Myelin sheath ...
6.2 Transmission of Nerve Impulses
... - neurons have the property of irritability similar to muscles - neurons also have the property of conductivity = the ability to convert a stimulus into a nerve impulse A. Action Potentials 1. A neuron at rest has more sodium ions (Na+) outside the membrane than potassium (K+) ions inside, therefore ...
... - neurons have the property of irritability similar to muscles - neurons also have the property of conductivity = the ability to convert a stimulus into a nerve impulse A. Action Potentials 1. A neuron at rest has more sodium ions (Na+) outside the membrane than potassium (K+) ions inside, therefore ...
48 - Groupfusion.net
... -excitatory or inhibitory at other sites. ex)heart muscles-> inhibitory -certain bacteria produce a toxin that specifically inhibits presynaptic release of acetylcholine; toxin caused of food poisoning called botulism ...
... -excitatory or inhibitory at other sites. ex)heart muscles-> inhibitory -certain bacteria produce a toxin that specifically inhibits presynaptic release of acetylcholine; toxin caused of food poisoning called botulism ...
Ch. 48-49 Nervous System 9e S13
... The Na+/K+ pump (using ATP) maintains a negative potential inside the neuron. ...
... The Na+/K+ pump (using ATP) maintains a negative potential inside the neuron. ...
Neuron Structure and Function
... inside. Negative protein ions on inside. The neuron is said to be polarized. This is due to the Na+/K+ pump. ...
... inside. Negative protein ions on inside. The neuron is said to be polarized. This is due to the Na+/K+ pump. ...
Chapter 5b
... Potential changes can occur in soma, along dendrite or initial portions of axon Spreads along membrane, effect becomes smaller. If depolatrization is at least 10mv at axon hillock, action potential is triggered Smaller changes in potential will not influence neuron. ...
... Potential changes can occur in soma, along dendrite or initial portions of axon Spreads along membrane, effect becomes smaller. If depolatrization is at least 10mv at axon hillock, action potential is triggered Smaller changes in potential will not influence neuron. ...
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.