Membrane Potential Flashcards by JOSHUA DE ASIS

Receive, process, and transmit information to other cells

Neurons

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Part of the neuron that receives the signals from other neurons towards the cell body

Dendrites

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Conducts the signal away from the cell body and carriers it for long distances with high fidelity and without loss

Axon

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Contains all the necessary organelles for metabolic maintenance, the cell’s genetic information, and provides energy to drive activities.

Soma

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Different types of neurons:

Sensory or afferent
Motor or efferent
Interneuron

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Neuron that send the synapse towards another neuron

Presynaptic cell

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Neuron that receives the synapse from the presynaptic cell

Post-synaptic cell

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The surface membrane of motor-neuron dendrites and soma:

Innervated

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Part of the neuron that integrates input to initiate an action potential(AP)

Soma

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Action potential is carried from the __________ to the ____________

Spike initiating zone, Axon terminal

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The spike initiating zone is located near the _____________

Axon hillock

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The difference in electrical potential across the cell membrane that is caused by the different concentration of ions on each side of the plasma membrane.

Membrane Potential

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What is the membrane potential of neurons

-60 to -80 mV

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Fundamental property of cells from an excess negative or positive charge on either side of the plasma

Membrane Potential

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Electrical gradient that is more concentrated in the extracellular matrix

Cations(positive)

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Electrical gradient that is more concentrated with the cells or the cytosolic space.

Anions(negative)

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Every ________ has a voltage or membrane potential across its plasma membrane

Cell

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Factors that create potential difference

A. Concentration gradient for an ion
B. Membrane that is permeable to that ion

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What is the resting potential of a cell?

-70mV

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Measures the membrane potential across the cell

Microelectrode

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Movement of K+(potassium) in the cell

Outwards

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Movement of Na+(Sodium) in the cell

Inwards

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The state of equal anions and cations

Electroneutral

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Potassium moves out of the cell along concentration gradient using:

Potassium Channel

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Movement of potassium cations out of the cell results to:

Electronegativity inside of the cell

Movement of ions that causes inward and outward fluxes that exactly balance each other

Equilibrium potential

Represents the sum of the equilibrium potentials of all the relevant ions and the influence of each ion over the overall membrane potential is proportional to its permeability.

Goldman-Hodgkin-Katz equation

The molecule that sets the resting membrane potential of neurons

Potassium

The principal element for intracellular cation

K+(potassium)

Principal element for extracellular cation

Na+(sodium)

Cations that maintains membrane potential

K+ and Na+

Anions that maintain membrane potential

proteins, amino acids, sulfate, phosphate and Cl-

Principal intracellular anions

proteins, amino acids, sulfate, and phosphate

Principal extracellular anion

Cl- (chlorine)

The concentration of K+ is greater on the inside the cell, while the Na+ concentration is greater outside the cell.

Chemical potential energy

Uses ATP to maintain the K+ and Na+ gradients across the plasma membrane

Sodium-potassium pumps

Converts chemical potential energy to electrical potential

opening of ion channels

State of the neuron where it contains many open K+ channels and fewer open Na+ channels; K+ diffusion outside of the cell

Neuron at resting potential

Channels that are always open which allows ions to diffuse across the plasma membrane

Non-gated ion channels

Cells that can generate larges changes in their membrane potential

Excitable cells

Channels that responds by opening or closing to a stimuli

Gated ion channels

Types of gated ions

1. Chemically-gated ion channels 2. voltage-gated ion channels

Channel that opens or closes in response to a chemical stimuli

Chemically-gated ion channels

Channel that responses caused by stimuli generated by changes in membrane potential

Voltage-gated ion channels

Changes that occurs in the membrane potential

Graded potentials

Changes in the membrane potential gives rise to:

Nerve impulses

The phenomena where the membrane potential becomes more negative

Hyperpolarization

An occurrence where the membrane potential becomes less negative

Depolarization

All or nothing depolarization

Action potential

If the gradient potentials sum reaches -55mV that triggers an action potential

Threshold potential

What is the threshold potential of the cell

-55mV

Two gates of voltage-gated Na+ channels

1. Closed activation gates 2. Open inactivation gates

Voltage-gated Na+ channel that close slowly in response to depolarization

Open inactivation gates

Voltage-gated Na+ channels that open rapidly in response to depolarization

Close activation gates

A period where no second action potential can be initiated

Refractory period

Stages of Action potential

1. Resting stage 2. Depolarization 3. Rising Phase 4. Falling phase 5. Undershoot

Refractory period occurs due to:

Inactivation of Na+ channels

Movement of impulse are faster on myelinated neurons is caused by:

Saltatory conduction

Depolarized regions of the axon (unmyelinated regions)

nodes of Ranvier

Action potential that travels directly from the presynaptic to the postsynaptic cells via gap junctions

Electrical Synapses

Synapses received by chemically-gated channels for ions such as Na+, K+, and Cl-

Chemical Synapses

A region where neurons nearly touch and where nerve impulses are transferred

Synapse

Small gap between neurons

Synaptic cleft

Transmission across the synapse is carried out by:

Neurotransmitters

Formation of myelin sheath around a nerve

Myelination

Diameter of an axon

One(1) micrometer

Affect how false the impulses move

Temperature

Velocity of an impulse propagation varies as a function of:

Axon diameter and myelination

How fast the membrane ahead of the active region is brought to threshold by the local-circuit current

Conduction velocity of action potential

Increase the transmembrane resistance and decrease the effective neuronal membrane capacitance

Myelination

The greater the length constant;

The faster the conduction of action potential

Less capitative current is required to change the Vm; more charge can flow down the axon to depolarize the next segment

Capacitance decrease