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Voltage impulses in neuronal dendrites which vary in strength. (and btw, the following previous DETAILED answer is WONDERFUL!!)
Upon being stimulated (by another neuron or as a special receptor) the dendrites of a neuron produce a graded potential. Stimulation can occur in many ways, including chemical stimulation (neurotransmitters, etc.), mechanical stimulation (certain pain receptors, hair receptor, etc.), light stimulation (photoreceptors) and a few other methods. Regardless of the method of stimulation the same general result is effected. Certain receptor protein ion channels on the dendrites are activated, and opened. This causes an influx (or efflux) of whatever ion the receptor channel was geared for. Thus it can cause either a depolarization (an excitatory response that may lead to an action potential) or hyperpolarization (an inhibitory response which makes it harder for an action potential to occur) depending on the ion let in (or out). The more receptor protein ion channels that are stimulated the stronger, or more intense the signal. A slight stimulation of a receptor protein ion channel will often open the channel and let in ions. However in order for a depolarization of threshold strength to reach the axon hillock, it generally requires multiple depolarizing receptor protein ion channels to open. Because of this, graded potentials are said to summate. In effect the total polarizing effect of the ion channels adds together. This is important in that one channel cannot stimulate an action potential, it takes multiple channels working in concert to depolarize a membrane enough to cause and action potential. Graded potentials (or receptor potentials when they occur in receptor cells) are short lived depolarizations or hyperpolarizations of an area of membrane. These changes cause local flows of current (current reflects the movement of ions) that decrease with distance. The magnitude of a graded potential is a direct reflection of the intensity or strength of the stimulus. The more intense the stimulus, the more ion channels that are opened, and the greater the voltage change (hyper or de- polarization) and the farther the current flows. Once stimulated polarization occurs as ions rush in. These ions accumulate very close to the stimulated area. From there the surplus of ions radiates out in all directions, polarizing adjoining membranes. As this polarization spreads like a wave it leaves behind it a wake of formerly polarized membrane that very quickly returns to resting membrane potential. As the wave of polarization ripples across the membrane it either summates (adds or subtracts) with other polarization waves or quickly looses intensity. This is in part due to the ever present leakage channels . Because the current dissapates quickly and is short lived graded, potentials can only act as signals over short distances. However their purpose is only to drive the axon hillock to threshold membrane potential, at which point an action potential will be generated.
changes in the transmembrane potential that cannot far from the site of stimulation
amplitude of various sizes
What else can I help you with?
What potentials are short-lived and decremental?
graded (local) potentials
Can graded potential form on receptor endings?
Graded potentials can form on receptor endings in response to stimuli such as pressure, temperature, or chemicals. These graded potentials can lead to the generation of action potentials that transmit the sensory information to the central nervous system for processing.
Are graded potentials the same as local potentials?
Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Graded potentials are changes in membrane potential that vary in size, as opposed to being all-or-none, and are not postsynaptic potentials.
How do graded potentials and action potentials differ in terms of their characteristics and functions?
Graded potentials are small changes in membrane potential that can vary in size and duration, while action potentials are brief, large changes in membrane potential that are all-or-nothing. Graded potentials are used for short-distance communication within a neuron, while action potentials are used for long-distance communication between neurons.
Graded potentials will not be initiated by?
Graded potentials will not be initiated by hyperpolarization. Graded potentials are subthreshold changes in membrane potential that can depolarize or hyperpolarize a cell, but they are typically initiated by a stimulus, such as neurotransmitter binding or sensory input. Hyperpolarization alone may not be strong enough to reach the threshold for generating a graded potential.
Local potentials that vary in magnitude according to the strength of the stimulus?
Graded potentials are local potentials that vary in magnitude according to the strength of the stimulus. They can either be depolarizing or hyperpolarizing and play a role in generating action potentials in neurons. Graded potentials are responsible for the integration of multiple signals in the nervous system.
Do graded potentials increase amplitude as they move away from the stimulus?
No, graded potentials do not increase in amplitude as they move away from the stimulus. The amplitude of graded potentials will decrease with distance from the stimulus site due to the loss of charge.
How does an action potential differ from a graded potential?
An action potential is a rapid and all-or-nothing electrical signal that travels along the axon of a neuron, while a graded potential is a small and variable electrical signal that occurs in response to a stimulus. Action potentials are typically generated in neurons, while graded potentials can occur in various types of cells.
Dendrites conduct both graded and action potential?
Dendrites primarily conduct graded potentials, which are local changes in membrane potential. These graded potentials can accumulate and trigger an action potential in the axon hillock if they reach a certain threshold. Action potentials are then conducted along the axon.
Graded potential are they all or none?
graded potential are by definition VARIABLE in strength, and therefore NOT all or none. They start out at their strongest strength, and degrade (become weaker) as they progress further along.
How are graded potentials different from action potentials in terms of their characteristics and functions in neuronal communication?
Graded potentials are small changes in membrane potential that can vary in size and can be either depolarizing or hyperpolarizing. They are localized and decay over distance. Graded potentials are important for short-distance communication within a neuron. Action potentials, on the other hand, are large, all-or-nothing electrical impulses that travel along the axon of a neuron. They are always depolarizing and do not decay over distance. Action potentials are crucial for long-distance communication between neurons.
Where do graded potentials occur?
On the dendrites and subsequently the soma (body) of neurons.
