Facilitative transport is a passive diffusion mechanism where a molecule binds to a protein transporter and moves from a region of high concentration to one of low concentration without requiring energy.
The process by which an action potential travels along the axon of a neuron, allowing for the transmission of nerve signals.
The Na+ - K+ pump pumps more sodium ions outside the cell than potassium ions inside, contributing to a continual loss of positive charges from inside the membrane and creating additional negativity.
The threshold potential is usually around −55 millivolts, which triggers a conformational change in the activation gate of the sodium channel, allowing it to open.
During an action potential, the membrane potential undergoes successive changes over a few 10,000ths of a second, illustrating an explosive onset and rapid recovery.
Facilitated Diffusion is a process that allows substances to cross membranes with the assistance of special proteins, without the expenditure of energy.
The diffusion of sodium and potassium ions contributes to the membrane potential by creating a balance of charges, but the Na+ - K+ pump enhances this effect by causing a net loss of positive charges inside the membrane.
An electrical signal is a wave of voltage or current that carries information through a medium, often used in the context of nerve impulses or communication between cells.
Potassium conductance increases only about 30-fold during the latter stages of the action potential and for a short period thereafter.
Facilitated Diffusion requires interaction of a carrier protein that aids the passage of molecules or ions through the membrane by binding chemically with them and shuttling them through the membrane.
The resting stage is the resting membrane potential before the action potential begins, characterized by a polarized membrane with a negative membrane potential of −70 millivolts.
A sensory neuron is a type of neuron that transforms a physical stimulus, such as a stretch, into electrical activity in the cell.
A diffusion potential is the electrical potential difference that develops across a membrane due to the diffusion of ions, resulting in a separation of charge.
Activation of the insulin receptor leads to the activation of phosphoinositide 3-kinase, which speeds up the translocation of GLUT 4-containing endosomes to the cell membrane.
Spatial Summation is the process by which simultaneous stimuli from multiple synapses can combine to produce a greater postsynaptic potential.
Adaptation refers to the decrease in the frequency of discharge in afferent nerve fibers over time when sustained stimulation occurs.
An action potential is a rapid rise and fall in voltage across a cellular membrane, which occurs when a neuron is stimulated, leading to the propagation of electrical signals along the axon.
Ionic channels are protein structures in cell membranes that allow ions to pass through, facilitating the movement of charged particles across the membrane.
The Glucose transporter (GLUT) protein facilitates the passive transport of glucose across the cell membrane by binding to glucose and allowing it to move down its concentration gradient.
Ion channels allow specific ions to flow in and out of the cell, contributing to the establishment and maintenance of the resting membrane potential.
The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, helping to maintain the negative resting membrane potential.
Slowly adapting receptors that fire rapidly when first activated, then slow and maintain their firing as long as the stimulus is present. They are responsible for monitoring parameters that must be continuously observed by the body.
The equilibrium potential for K+ (EK) is -90 mV.
The process by which local current flow causes the threshold potential to be exceeded in adjacent areas of the neuron membrane, allowing the action potential to move downstream.
A membrane protein that actively transports sodium ions out of the cell and potassium ions into the cell, crucial for maintaining cellular ion balance.
The Positive afterpotential is a phase following the action potential where the membrane potential temporarily becomes more positive than the resting potential due to continued ion conductance, particularly of Na+.
An action potential is a rapid change in membrane potential that occurs when positive charges are transferred to the interior of a fiber at its onset and return to the exterior at its end.
The Resting Membrane Potential is the membrane potential caused by the diffusion of sodium and potassium ions, along with the pumping of these ions by the Na+ - K+ pump, resulting in a continual loss of positive charges from inside the membrane, creating additional negativity.
1) Through the interstices of the lipid bilayer if the diffusing substance is lipid soluble. 2) Through watery channels that penetrate all the way through some of the large transport proteins.
Sensory neurons use action potential duration to code for stimulus duration.
When sodium ions diffuse through a membrane that is permeable only to them, the internal membrane potential becomes positive due to the opposite concentration gradient compared to potassium.
Cation channels are membrane proteins that allow the selective passage of positively charged ions (cations) such as sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) across the cell membrane.
The Schwann cell insulates nerve fibers by wrapping its membrane around axons to form the myelin sheath in myelinated nerve fibers.
Saltatory conduction is the process by which action potentials 'leap' from node to node along a myelinated axon, occurring at gaps in the myelin sheath called the nodes of Ranvier.
The myelin sheath is a protective covering formed by the wrapping of Schwann cell membranes around large axons, which facilitates faster nerve signal transmission.
The chemical compositions refer to the specific ions and molecules present in the extracellular and intracellular fluids, with precise values for intracellular fluid being unknown.
The membrane potential is determined by the uneven distribution of ions (charged particles) between the inside and the outside of the cell.
The sodium-potassium pump is a mechanism that transports two potassium ions (K+) into the cell while removing three sodium ions (Na+) per ATP consumed, helping to maintain the resting potential.
A sensory neuron converts a physical stimulus into electrical activity, allowing the nervous system to process the information.
The resting membrane potential is crucial for the excitability of neurons, as it sets the stage for action potentials and signal transmission.
Potassium ions diffuse from inside the cell to outside through a selectively permeable membrane, creating a negative internal membrane potential.
GLUT 4-containing endosomes are vesicles that transport GLUT 4 transporters to the cell membrane in response to insulin signaling.
An Action Potential is a rapid, temporary change in the membrane potential of a neuron, allowing for the transmission of electrical signals along the nerve fiber.
Convergence refers to the phenomenon where one neuron is influenced by many other neurons, integrating multiple inputs.
A refractory region is one that has just produced an action potential and is temporarily unable to generate another action potential due to the inactivation of sodium channels.
The threshold potential is the critical level of depolarization that must be reached for an action potential to be initiated in a neuron.
An action potential is a rapid change in the membrane potential that spreads along the nerve fiber membrane, beginning with a sudden change from a negative to a positive potential and then returning to a negative potential.
A nucleotide that plays a key role in energy transfer within cells, often produced from ATP during energy utilization.
Transmembrane potentials refer to the voltage difference across a cell membrane, which is crucial for the generation of action potentials and the overall function of excitable cells.
Transmembrane transport refers to the movement of substances across a biological membrane, which can occur via passive or active mechanisms.
The resting membrane potential is determined by the uneven distribution of ions (charged particles) between the inside and the outside of the cell, and by the different permeability of the membrane to different types of ions.
The membrane suddenly becomes permeable to sodium ions, allowing rapid diffusion of positively charged sodium ions to the interior of the axon, neutralizing the normal polarized state of −70 millivolts and causing the potential to rise rapidly in the positive direction.
An action potential is a rapid, temporary change in the membrane potential of a neuron that occurs when the membrane potential reaches a certain threshold.
The inflowing, positively charged sodium ions neutralize the normal polarized state, causing the membrane potential to overshoot beyond zero and become somewhat positive.
Leak channels are specialized channels in the cell membrane that allow potassium and sodium cations to diffuse down their concentration gradients, with a higher prevalence of potassium channels in neurons.
The threshold is the critical level of depolarization that must be reached for an action potential to occur.
The kinetic movement of molecules or ions occurs through a membrane opening without any interaction with carrier proteins in the membrane.
LIGAND-GATED CHANNELS are ionotropic receptors that open in response to the binding of a specific ligand, allowing ions to flow across the cell membrane.
The Nernst equation is used to calculate the equilibrium potential for ions such as Cl–, K+, and Na+.
GLUT 4 is a glucose transporter protein that mediates glucose transport into cells, particularly in insulin-sensitive tissues.
Action potential frequency in sensory neurons codes for stimulus intensity.
When the membrane potential rises from −70 millivolts toward zero, it becomes less negative and can reach the threshold potential, causing the sodium channel to activate and open.
The equilibrium potential for Na+ (ENa) at 37 °C is +60 mV.
The resting membrane potential is the electrical potential difference across the plasma membrane of a cell when it is not actively transmitting signals, typically around -70 mV in neurons.
GLUT proteins are a family of transport proteins that facilitate the transport of glucose across the plasma membrane of cells.
The sodium-potassium pump expels more cations from the cell than it takes in, resulting in the inside of the cell remaining negatively charged relative to the extracellular fluid.
Sodium conductance increases several thousand-fold during the early stages of the action potential.
A phasic receptor is a type of sensory receptor that responds quickly to changes in stimulus intensity but adapts rapidly, providing little information about the ongoing stimulus.
Receptors are specialized proteins located on cell membranes or within cells that bind to specific molecules (ligands) such as hormones, neurotransmitters, or drugs, initiating a cellular response.
The resting membrane potential established entirely by the diffusion of potassium ions across the membrane.
The upstroke of the action potential results from increased Na+ conductance.
Voltage-gated ion channels open in response to changes in membrane potential, allowing ions to flow in and out of the neuron, which is crucial for the generation and propagation of action potentials.
An action potential is a rapid, temporary change in the membrane potential of a neuron, allowing for the transmission of electrical signals along the nerve cell.
Repolarization occurs when potassium ions (K+) exit the cell, causing the membrane potential to return to a more negative value.
Adjacent regions become partially depolarized due to the spread of positive charges from the region that just produced an action potential, leading to the opening of voltage-regulated Na+ gates.
During the depolarization phase, the membrane potential becomes more positive as sodium ions rush into the neuron through voltage-gated sodium channels.
Positive feedback in Na+ channels refers to the mechanism where the opening of Na+ channels leads to an increase in Na+ permeability, further depolarizing the membrane potential.
The myelin sheath prevents inward Na+ current, allowing action potentials to be generated only at the nodes of Ranvier, facilitating faster nerve impulse conduction through saltatory conduction.
The initial electrotonic depolarization initiates the change in Na+ conductance, which further enhances depolarization.
Sensory receptors are part of a neuron or specialized cells that generate action potentials in response to specific forms of energy, such as mechanical, thermal, electromagnetic, and chemical energy.
Electromagnetic receptors are sensory receptors that detect light on the retina of the eye.
Temporal summation of EPSPs happens when the same presynaptic fiber fires action potentials in quick succession, leading to the addition of individual EPSPs.
IPSP is a change in the postsynaptic membrane potential that makes it less likely to fire an action potential.
Receptors convert various forms of energy, including mechanical (touch-pressure), thermal (degrees of warmth), electromagnetic (light), and chemical energy (odor, taste).
Nodes of Ranvier are gaps in the myelin sheath along the axon where action potentials are regenerated, facilitating rapid signal transmission.
Neurons have far more potassium leakage channels than sodium leakage channels, resulting in a faster rate of potassium diffusion out of the cell compared to sodium diffusion into the cell.
Temporal Summation is the process by which multiple stimuli occurring in rapid succession at the same synapse can combine to produce a greater postsynaptic potential.
Spatial summation refers to the process by which multiple synaptic inputs from different neurons combine to produce a greater postsynaptic potential, potentially reaching the threshold for action potential generation.
A tonic receptor is a type of sensory receptor that responds slowly to a stimulus and continues to produce action potentials as long as the stimulus is present, providing continuous information about the stimulus.
The successive stages of the action potential include depolarization, repolarization, and hyperpolarization, which occur in response to changes in membrane permeability to ions.
A selectively permeable membrane allows certain ions or molecules to pass through while restricting others, influencing the establishment of diffusion potentials.
During the Repolarization Stage, sodium channels begin to close after the membrane becomes highly permeable to sodium ions.
Divergence is the process where one neuron influences many other neurons, allowing a single signal to spread to multiple targets.
Na+ conductance increases during the action potential, contributing to the depolarization of the membrane and the generation of the action potential.
Threshold potential is the level of depolarization that must be reached for an action potential to be initiated.
K+ conductance increases after the peak of the action potential, leading to repolarization of the membrane as K+ ions exit the cell.
Depolarization is the process by which the membrane potential becomes less negative (or more positive) due to the influx of sodium ions through voltage-gated sodium channels.
In an excited state, the intraneuronal potential becomes less negative (−45 mV) due to sodium influx.
A rise in membrane potential from -70 mV toward zero causes a conformational change that opens the potassium channel gate.
EPSPs, or excitatory post synaptic potentials, are changes in the postsynaptic membrane potential that result from the opening of cation channels, allowing cations like Na+, K+, and Ca2+ to pass through.
Receptors are proteins that bind neurotransmitters, hormones, and other substances with great affinity and specificity, initiating specific physiological responses.
Sensory receptors are specialized cells or structures that detect and respond to specific types of stimuli, such as light, sound, or pressure, and convert these stimuli into neural signals.
Terminal buttons (boutons) are located at the terminal endings of a motor neuron and are involved in transmitting signals to other neurons or muscles.
A presynaptic action potential triggers a small EPSP in a postsynaptic neuron.
Mechanoreceptors are sensory receptors that respond to mechanical pressure or distortion, playing a crucial role in the sense of touch, hearing, and balance.
A receptor potential is a graded change in the membrane potential of a sensory receptor in response to a stimulus.
The most common synapse occurs between the axon of the presynaptic neuron and the dendrites or cell body of the postsynaptic neuron.
The greater outflow of potassium compared to the inflow of sodium causes the interior of the cell to become negatively charged relative to the outside.
During the activated state, sodium ions can flow inward through the channel, significantly increasing the sodium permeability of the membrane by 500 to 5000 times.
Threshold potential is the critical level of depolarization that must be reached for an action potential to be initiated in a neuron.
The opening of the potassium gate increases membrane permeability to potassium ions, leading to increased potassium conductance.
Firing level is the membrane potential at which a neuron will fire an action potential, typically around -55 mV in many neurons.
The All - or - Nothing Principle states that once an action potential is elicited at any point on the membrane of a normal fiber, the depolarization process travels over the entire membrane if conditions are right, but does not travel at all if conditions are not right.
A receptor potential is a graded change in the membrane potential of a sensory receptor cell in response to a stimulus, which can lead to the generation of action potentials.
Ionotropic receptors are receptors that bind to inhibitory neurotransmitters and contain chloride channels (anion channels), leading to the opening of these channels and resulting in inhibitory post synaptic potentials (IPSPs).
Several action potentials form in response to a suprathreshold stimulus.
Metabotropic receptors are a type of receptor that, when bound by inhibitory neurotransmitters, are linked to K+ channels, leading to changes in the postsynaptic cell's membrane potential.
A high-energy molecule that serves as the primary energy currency of the cell, providing energy for various cellular processes including the Na+ - K+ pump.
EPSP summation refers to the process by which excitatory postsynaptic potentials (EPSPs) combine to increase the likelihood of a postsynaptic neuron firing an action potential.
Repolarization is the process by which the membrane potential returns to its resting state after depolarization, primarily through the efflux of potassium ions via voltage-gated potassium channels.
Rapidly adapting (phasic) receptors are sensory receptors that respond quickly to changes in stimulus intensity but decrease their response to a constant stimulus over time.
When cation channels open, they allow the passage of Na+, K+, and Ca2+, with Na+ inflow being greater, leading to depolarization of the postsynaptic cell.
Potassium channels generally open around the same time that sodium channels begin to close due to inactivation.
The inactivation gate closes a few 10,000ths of a second after the activation gate opens, which is a slower process, leading to the cessation of sodium ion influx.
The initial segment is the first portion of the axon that originates from the axon hillock and is crucial for the generation of action potentials.
The inactivation gate will not reopen until the membrane potential returns to or near the original resting membrane potential level.
Each of the neuron's four signaling components produces a characteristic signal in response to stimuli.
This voltage change causes the opening of the potassium channels gate, allowing increased potassium diffusion outward through the channel.
The equilibrium potential for Cl– (ECl) is -70 mV.
A subthreshold stimulus does not cause an action potential.
Voltage-gated sodium channels are specialized transport channels in the nerve membrane that open in response to changes in membrane potential, allowing sodium ions to flow into the cell, leading to depolarization.
A threshold stimulus is just strong enough to depolarize the membrane to threshold, resulting in an action potential.
Potassium ions rapidly diffuse to the exterior of the cell, which helps to reestablish the normal negative resting membrane potential during the Repolarization Stage.
The change in membrane potential of a sensory receptor cell in response to a stimulus, which can lead to the generation of an action potential.
'All or None' principle states that once a threshold is reached, an action potential is generated fully or not at all, without partial responses.
Depolarization is the process by which the membrane potential becomes less negative (more positive) due to the influx of sodium ions, leading to the initiation of an action potential.
Synapses facilitate communication between neurons by transmitting signals through neurotransmitter release, allowing for the integration and processing of information in the nervous system.
An action potential is initiated by a sudden change from the normal resting negative membrane potential to a positive potential.
Neurotransmitters are chemical messengers released from the presynaptic neuron that bind to receptors on the postsynaptic neuron, initiating a response and propagating the signal.
The Node of Ranvier converts the graded response of the receptor into action potentials once the firing level is reached.
Slowly adapting (tonic) receptors are sensory receptors that continue to respond to a constant stimulus over time, providing ongoing information about the stimulus.
The inflow of Na+ makes the inside of the postsynaptic cell less negative, resulting in depolarization.
Repolarization of membrane potential is the process by which the membrane potential returns to a more negative value after depolarization, primarily due to the increased flow of K+ out of the cell.
EPSPs are graded changes in membrane potential that make a neuron more likely to fire an action potential.
The Ca++ pump is an active transport mechanism that moves calcium ions out of the cell, helping to regulate intracellular calcium levels critical for various cellular processes.
In the Peripheral Nervous System, the other cell in a synapse may be either a neuron or an effector cell within a muscle or gland.
Gated channels are specialized protein structures in cell membranes that open or close in response to specific stimuli, allowing ions to pass through the membrane.
Rapidly adapting receptors that fire when they first receive a stimulus but cease firing if the strength of the stimulus remains constant. They are attuned specifically to changes in a parameter and allow the body to ignore non-threatening information.
Repolarization Stage is the phase where sodium channels close and potassium channels open, allowing rapid diffusion of potassium ions out of the cell, reestablishing the normal negative resting membrane potential.
During depolarization, the membrane potential becomes more positive due to the influx of sodium ions (Na+) through voltage-gated sodium channels.
The Na+ - K+ pump actively transports more sodium ions out of the cell than potassium ions into the cell, contributing to a more negative resting membrane potential.
Transmission across the majority of synapses in the nervous system that is one-way and mediated by chemical neurotransmitters released from presynaptic axon endings.
Voltage-gated potassium channels are specialized transport channels in the nerve membrane that open in response to depolarization, allowing potassium ions to flow out of the cell, which contributes to repolarization.
The normal intraneuronal potential of a resting neuron, which is −65 mV.
Nerve signals are transmitted by action potentials, which are rapid changes in the membrane potential that propagate along the nerve fiber.
Responses persisted, indicating that the removal of the capsule affects adaptation but not the ability to generate responses.
Nociceptors, also known as pain receptors, detect damage occurring in the tissues, whether it is physical or chemical damage.
When Cl− channels open, a larger number of chloride ions diffuse inward, causing the inside of the postsynaptic cell to become more negative (hyperpolarized).
PNa and PK represent the permeability of the membrane to Na+ and K+ ions, respectively.
EPSP is a change in the postsynaptic membrane potential that makes it more likely to fire an action potential.
Saltatory conduction is the process by which electrical impulses jump from one Node of Ranvier to another along a myelinated axon, allowing for faster transmission of nerve signals.
Synaptic integration is the process by which multiple synaptic inputs are combined in the postsynaptic neuron to determine whether an action potential will be generated.
Repolarization is the process where the membrane potential begins to return toward the resting membrane state after the inactivation gate of the sodium channel closes.
A reflex arc is a neural pathway that controls a reflex action, involving a receptor, sensory neuron, integration center, motor neuron, and effector.
Thermoreceptors are sensory receptors that detect changes in temperature, allowing the body to sense hot and cold environments.
Convergence allows multiple inputs to influence the activity of efferent neurons or synaptic stations within the reflex arc, modifying the reflex response.
1) The amount of substance available. 2) The velocity of kinetic motion. 3) The number and sizes of openings in the membrane through which the molecules or ions can move.
A neuron action potential is a rapid, temporary change in the membrane potential of a neuron, allowing it to transmit electrical signals along its axon.
The resting membrane potential established by the simultaneous diffusion of both sodium and potassium ions across the membrane.
A method of action potential propagation in myelinated axons where the action potential jumps from one node of Ranvier to the next, resulting in faster transmission.
Repolarization results from a declining Na+ conductance combined with an increasing K+ conductance.
Overshoot refers to the phenomenon where the membrane potential temporarily exceeds the resting potential during an action potential.
Nodes of Ranvier are gaps in the myelin sheath of a myelinated axon where action potentials are produced, allowing for saltatory conduction.
Swollen appearances at the endings of presynaptic axons where neurotransmitters are released.
In an unmyelinated axon, action potentials are regenerated in successive segments as each segment becomes depolarized and then refractory, allowing the signal to propagate along the axon.
Ionotropic receptors are receptors that bind excitatory neurotransmitters and contain cation channels, leading to the generation of excitatory post synaptic potentials (EPSPs).
Opening K+ channels allows a larger number of potassium ions to diffuse outward, causing the inside of the postsynaptic cell to become more negative, or hyperpolarized.
RRP stands for relative refractory period.
IPSPs (Inhibitory Postsynaptic Potentials) result from the opening of K+ channels linked to metabotropic receptors, leading to hyperpolarization of the postsynaptic cell.
O2 Leak channels are specialized pathways in the cell membrane that allow oxygen to passively diffuse into the cell, contributing to cellular respiration.
An adequate stimulus is the particular form of energy to which a receptor is adapted to respond at a much lower threshold than other receptors respond to that form of energy.
The Node of Ranvier is a small gap in the myelin sheath of a myelinated axon where the axonal membrane is exposed, facilitating the rapid conduction of electrical impulses.
Positive charges injected at the Node of Ranvier spread to adjacent nodes, enabling the rapid propagation of the electrical current along the axon.
Repolarization is necessary because it allows the sodium channels to reset and become available for opening again; without it, the channels cannot open again.
Neuron-to-neuron synapses can involve connections between the axon of one neuron and the dendrites (axodendritic), cell body (axosomatic), or axon (axoaxonic) of a second neuron.
The height of the curve indicates the frequency of the discharge in afferent nerve fibers at various times after the beginning of sustained stimulation.
A rapid, temporary change in the membrane potential of a neuron or muscle cell that occurs when the cell is stimulated, leading to the transmission of an electrical signal.
A state in which the upstream region of a neuron membrane cannot generate another action potential, ensuring that the action potential only propagates downstream.
The Na+ - K+ pump causes a continual loss of positive charges from inside the membrane, creating an additional degree of negativity (about −4 millivolts) beyond what is accounted for by diffusion alone.
Hyperpolarization is the stage where the membrane potential becomes more negative than the resting potential, often due to prolonged potassium ion efflux.
The gate of the potassium channel is closed, preventing potassium ions from passing through to the exterior.
Repolarization is the phase following depolarization where the membrane potential returns to a more negative value, primarily due to the efflux of potassium ions.
Local responses are changes in membrane potential that occur in a localized area of the neuron, which may not lead to an action potential unless the threshold is reached.
Hyperpolarization is the process by which the membrane potential becomes more negative than the resting potential, making it less likely for an action potential to occur.
The increase in potassium exit from the cell, combined with the decrease in sodium entry, speeds up the repolarization process.
The inactivation of the Sodium Channel refers to the process where, after a brief period of being open, the inactivation gate closes, preventing sodium ions from entering the membrane, which leads to the repolarization of the membrane potential.
gNa and gK represent the conductance of Na+ and K+ ions, respectively, indicating how easily these ions can flow through their channels.
Slow adaptation of muscle spindle input is needed to maintain posture by providing continuous feedback about muscle length and tension.
The Glucose transporter (GLUT) facilitates the transport of glucose across the cell membrane through facilitated diffusion, allowing cells to uptake glucose for energy.
Chemoreceptors are sensory receptors that detect chemical stimuli, such as taste and smell, and are essential for the senses of taste and olfaction.
In almost all synapses, transmission occurs in one direction only, from the axon of the presynaptic neuron to the postsynaptic neuron.
Ion channels that allow potassium ions to move out of the cell, contributing to the resting membrane potential, while also permitting a slight influx of sodium ions.
Mechanoreceptors are sensory receptors that detect mechanical compression or stretching of the receptor or of tissues adjacent to the receptor.
Voltage-gated ion channels are specialized proteins that open or close in response to changes in membrane potential, allowing ions to flow in and out of the cell, which is crucial for the generation and propagation of action potentials.
Partial wrapping of Schwann cell membrane and cytoplasm occurs around multiple unmyelinated nerve fibers, providing some level of insulation.
Na+ conductance decreases as sodium channels close, while K+ conductance increases as potassium channels open, facilitating the repolarization of the membrane.
ARP stands for absolute refractory period.
Adaptation is the process where the frequency of action potentials in a sensory nerve declines over time when a maintained stimulus of constant strength is applied to a receptor.
The magnitude of the generator potential increases as the stimulus is increased, and it is proportionate to the intensity of the stimulus.
Spatial summation of EPSPs occurs when two or more presynaptic inputs are active simultaneously, causing their individual EPSPs to add together.
Changes in membrane potential that vary in size and are proportional to the strength of the stimulus, unlike action potentials which are all-or-nothing.
A receptor potential is the change in membrane potential of a sensory receptor that is proportional to the strength of the stimulus.
The Na+/K+ pump is an active transport mechanism that moves sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient essential for cellular function.
The sensory nerve continues to fire as long as the generator potential is large enough to bring the membrane potential of the node to the firing level.
Ion pumps are membrane proteins that actively transport ions across the cell membrane against their concentration gradient, using energy from ATP.
A graded response is a type of response that varies in magnitude depending on the strength of the stimulus, rather than being an all-or-none response.
At the neuromuscular junction, a graded response occurs that is typically large enough to produce a contraction in skeletal muscle.
Myoneural junctions, also known as neuromuscular junctions, refer to synapses between neurons and muscle cells.
A channel that opens in response to changes in membrane potential, allowing potassium ions to diffuse outward, contributing to repolarization during an action potential.
Afterhyperpolarization is due to sustained high K+ conductance.
Thermoreceptors are sensory receptors that detect changes in temperature, with some receptors specifically detecting cold and others warmth.
IPSPs (inhibitory post synaptic potentials) are changes in the postsynaptic membrane potential that result from the opening of chloride channels, causing the inside of the postsynaptic cell to become more negative (hyperpolarized).
The 10 nm gap that separates the presynaptic cell from the postsynaptic cell in a chemical synapse.
A motor neuron is a type of neuron that comprises a cell body (soma) with a nucleus, several dendrites, and a long fibrous axon originating from the axon hillock.
A neuron in an inhibited state has a more negative intraneuronal membrane potential (−70 mV) caused by potassium ion efflux, chloride ion influx, or both.
The myelin sheath is a protective covering formed from Schwann cells that surrounds the axon of a motor neuron, except at its endings and at the nodes of Ranvier.
Chemoreceptors are sensory receptors that detect taste in the mouth, smell in the nose, oxygen level in the arterial blood, osmolality of body fluids, carbon dioxide concentration, and other factors related to the body's chemistry.
As the generator potential becomes larger, the sensory nerve fires repetitively, with the frequency of firing being proportionate to the magnitude of the applied stimuli.
All-or-none action potentials refer to the principle that action potentials either occur fully or not at all, with their frequency being proportional to the size of the receptor potential.
Nonspecific responses occur when receptors respond to forms of energy other than their adequate stimuli, but the threshold for these responses is much higher.
Lipid soluble substances are molecules that can easily pass through the lipid bilayer of the cell membrane due to their hydrophobic nature, allowing for passive diffusion.
A synapse is the functional connection between a neuron and a second cell, which can be another neuron in the CNS or an effector cell in the PNS.
Postsynaptic potentials are changes in the membrane potential of a postsynaptic neuron that occur in response to neurotransmitter binding, which can be either excitatory (EPSP) or inhibitory (IPSP).
A generator potential, or receptor potential, is a non-propagated depolarizing potential that occurs when a stimulus is applied to a receptor, converting energy into an electrical response.
No, each of the action potentials caused by the suprathreshold stimulus has the same amplitude as the action potential caused by the threshold stimulus.
Negative feedback in K+ channels refers to the mechanism where the opening of K+ channels leads to an increase in K+ permeability, resulting in repolarization of the membrane potential.
The inability of sensory receptors to decrease their response to a constant stimulus over time, leading to persistent signaling.
At the end of an action potential, there is an almost equally rapid change back to the negative membrane potential.
Synapses are involved in neural plasticity by strengthening or weakening connections based on activity, which is essential for learning and memory.
Action potentials conduct nerve signals along the nerve fiber until they reach the end of the fiber.
Photoreceptors are sensory receptors that respond to light and are primarily found in the retina of the eye, enabling vision.
Input from nociceptors provides a warning signal that would lose its value if it adapted and disappeared, ensuring that harmful stimuli are continuously detected.
IPSPs are graded changes in membrane potential that make a neuron less likely to fire an action potential.
Efferent motor nerves transmit action potentials to the effector, inducing a graded response that can lead to muscle contraction.
Action potentials are all-or-none electrical impulses that are propagated along nerve fibers, resulting in the transmission of signals.
A postsynaptic potential is a change in the membrane potential of a postsynaptic neuron, which can be either excitatory or inhibitory, depending on the neurotransmitter released.
