Membrane Potential Flashcards
Receive, process, and transmit information to other cells
Neurons
Part of the neuron that receives the signals from other neurons towards the cell body
Dendrites
Conducts the signal away from the cell body and carriers it for long distances with high fidelity and without loss
Axon
Contains all the necessary organelles for metabolic maintenance, the cell’s genetic information, and provides energy to drive activities.
Soma
Different types of neurons:
- Sensory or afferent
- Motor or efferent
- Interneuron
Neuron that send the synapse towards another neuron
Presynaptic cell
Neuron that receives the synapse from the presynaptic cell
Post-synaptic cell
The surface membrane of motor-neuron dendrites and soma:
Innervated
Part of the neuron that integrates input to initiate an action potential(AP)
Soma
Action potential is carried from the __________ to the ____________
Spike initiating zone, Axon terminal
The spike initiating zone is located near the _____________
Axon hillock
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
What is the membrane potential of neurons
-60 to -80 mV
Fundamental property of cells from an excess negative or positive charge on either side of the plasma
Membrane Potential
Electrical gradient that is more concentrated in the extracellular matrix
Cations(positive)
Electrical gradient that is more concentrated with the cells or the cytosolic space.
Anions(negative)
Every ________ has a voltage or membrane potential across its plasma membrane
Cell
Factors that create potential difference
A. Concentration gradient for an ion
B. Membrane that is permeable to that ion
What is the resting potential of a cell?
-70mV
Measures the membrane potential across the cell
Microelectrode
Movement of K+(potassium) in the cell
Outwards
Movement of Na+(Sodium) in the cell
Inwards
The state of equal anions and cations
Electroneutral
Potassium moves out of the cell along concentration gradient using:
Potassium Channel
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
- Chemically-gated ion channels
- 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
- Closed activation gates
- 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
- Resting stage
- Depolarization
- Rising Phase
- Falling phase
- 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