action potential

69問 • 2年前

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the functions of the nervous system -______,________,&______- depends on the functions of the neurons underlying these pathways

sensation, integration & response

to understand how you are able to communicate it is necessary to describe the role of an __________in generating the signals

excitable membranes

primarily responsible for regulating what can cross the membrane and what stays on only one side

cell membrane

charged particles cannot pass through the cell membrane without assistance

hydrophilic

moves 3 sodium ions (NA+) out of the cell and 2 potassium ions (K+) into a cell, thus regulating ions concentration on both sides of the cell membrane

sodium/potassium pump

sodium/ potassium pump requires energy in the form of _______________, also referred to as an _________.

adenosine triphosphate (ATP) ATPase

are pores that allow specific charged particles to cross the membrane in response to an existing concentration gradient

ion channels

found in the domain that are apposed to the hydrocarbon tails of the phospholipids

hydrophobic Amino acids

exposed to the fluid environment of the extracellular fluid and cytosol

hydrophilic Amino acids

_______will have negatively charged side chains in the pore

channels for cations (positive ions)

_____ will have positively charged side chains in the pores

channels for anions (negative ions)

the channel pores is charged specific

electrochemical exclusion

larger pores are not ideal for smaller ions because the water molecules will interact by hydrogen bonds, more readily than the amino acids side chains

size exclusion

some ions channel are selective for charge but not nessesary for size and thus called a

nonspecific channel

opens because a signaling molecules, a ligand, binds to the extracellular region of the channel

ligand - gated channel

ligand gated channels is also known as

ionotropic receptors

when the ligand, known as a neurotransmitter in the nervous system, binds to the protein, ions cross the membrane changing its charge

ligand gated channels ( ionotropic receptors

opens because of a physical distortion of the cell membrane

mechanically gated channels

many channels associated with the sense of touch (somatosensation) are

mechanically gated channels

as pressure is applied to the skin, these channel opens and allow ions to enter the cells. also in temperature changes, as in testing the water in the shower

mechanically gated channels

is a channel that responds to changes in the electrical properties of the membrane in which it is embedded

voltage gated channels

normally the inner portion of the membrane is at a negative voltage. when that voltage become less negative, the channel begins to allow to cross the membrane

voltage-gated channels

is randomly gated, meaning that it open and closes at random, hence the reference to leaking .

leakage channel

there is no actual event that opens the channel; instead it has an intrinsic rate of switching between the open and closed states

leakage channel

channel that contribute to the resting transmembrane voltage of the excitable membranes

leakage channel

time during an action period when another action potential cannot be generated because the voltage-gated Na+ channel is inactivated

absolute refractory period

change in voltage of a cell membrane in response to a stimulus that results in transmission of an electrical signal; unique to neurons and muscle fibers

action potential

part of the voltage-gated Na+ channel that opens when the membrane voltage reaches threshold

activation gate

connection between two neurons, or between a neuron and its target, where a neurotransmitter diffuses across a very short distance

chemical synapse

slow propagation of an action potential along an unmyelinated axon owing to voltage-gated Na+ channels located along the entire length of the cell membrane

continuous conduction

change in a cell membrane potential from rest toward zero

depolarization

enzyme that catalyzes the generation of a new molecule, which acts as the intracellular mediator of the signal that binds to the receptor

effector protein

connection between two neurons, or any two electrically active cells, where ions flow directly through channels spanning their adjacent cell membranes

electrical synapse

principle of selectively allowing ions through a channel on the basis of their charge

electrochemical exclusion

cell membrane that regulates the movement of ions so that an electrical signal can be generated

excitable membrane

property of a channel that determines how it opens under specific conditions, such as voltage change or physical deformation

gated

graded potential from dendrites of a unipolar cell which generates the action potential in the initial segment of that cell’s axon

generator potential

change in the membrane potential that varies in size, depending on the size of the stimulus that elicits it

graded potential

part of a voltage-gated Na+ channel that closes when the membrane potential reaches +30 mV

inactivation gate

graded potential in the postsynaptic membrane that is the result of hyperpolarization and makes an action potential less likely to occur

inhibitory postsynaptic potential (IPSP)

graded potential in the postsynaptic membrane that is the result of depolarization and makes an action potential more likely to occur

excitatory postsynaptic potential (EPSP)

first part of the axon as it emerges from the axon hillock, where the electrical signals known as action potentials are generated

initial segment

neurotransmitter receptor that acts as an ion channel gate, and opens by the binding of the neurotransmitter

ionotropic receptors

ion channel that opens randomly and is not gated to a specific event, also known as a non-gated channel

leakage channel

another name for an ionotropic receptor for which a neurotransmitter is the ligand

ligand-gated channels

ion channel that opens when a physical event directly affects the structure of the protein

mechanically gated channel

distribution of charge across the cell membrane, based on the charges of ions

membrane potential

movement of an action potential along the length of an axon

propagation

time after the initiation of an action potential when another action potential cannot be generated

refractory period

time during the refractory period when a new action potential can only be initiated by a stronger stimulus than the current action potential because voltage-gated K+ channels are not closed

relative refractory period

return of the membrane potential to its normally negative voltage at the end of the action potential

repolarization

property of an axon that relates to the ability of particles to diffuse through the cytoplasm; this is inversely proportional to the fiber diameter

resistance

the difference in voltage measured across a cell membrane under steady-state conditions, typically -70 mV

resting membrane potential

quick propagation of the action potential along a myelinated axon owing to voltage-gated Na+ channels being present only at the nodes of Ranvier

saltatory conduction

principle of selectively allowing ions through a channel on the basis of their relative size

size exclusion

to add together, as in the cumulative change in postsynaptic potentials toward reaching threshold in the membrane, either across a span of the membrane or over a certain amount of time

summate

membrane voltage at which an action potential is initiated

threshold

ion channel that opens because of a change in the charge distributed across the membrane where it is located

voltage-gated channel

Graded potentials produced by interactions between neurons at synapses are called

postsynaptic potentials (PSPs)

If the sensory stimulus is received by a specialized sensory receptor cell, the graded potential is called a

receptor potential

A depolarizing graded potential at a synapse is called

an excitatory PSP

hyperpolarizing graded potential at a synapse is called an

inhibitory PSP

combination of graded potentials at the same location on a neuron resulting in a strong signal from one input

temporal summation

"combination of graded potentials" across the neuronal cell membrane caused by signals from separate presynaptic elements that add up to initiate an action potential

spatial summation

type of acetylcholine receptor protein that is characterized by also binding to nicotine and is an ionotropic receptor

nicotinic receptors

graded potential in the postsynaptic membrane caused by the binding of neurotransmitter to protein receptors

postsynaptic potential (PSP)

channel that is not specific to one ion over another, such as a nonspecific cation channel that allows any positively charged ion across the membrane

nonspecific channel

type of acetylcholine receptor protein that is characterized by also binding to muscarine and is a metabotropic receptor

muscarinic receptor

neurotransmitter receptor that involves a complex of proteins that cause metabolic changes in a cell

metabotropic receptors

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Monica Ramos · 21問 · 3年前

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