Med neuroscience ch 2

Many neurons generate a special type of electrical signal that travels along their long axons called ___ ______, also referred to as spikes or impulses.

Action potentials

______ ___________are responsible for long range transmission of information within the nervous system and allow the nervous system to transmit information to its target organs, such as a muscle.

Action potentials

The displacement of a cell's membrane po- tential toward a more negative value

Hyperpolarization

The equilibrium potential can be predicted by the simple formula called the ____ _______

Nerst equation

What transient changes in potential are the first step in generating the sensation go vibrations of the skin in the somatosensory system

Receptor potential

An efflux of K is responsible for

Resting membrane pontential

What are fundamental problem for neurons sending signals?

Their axons can be quite long they are poor conductors of electricity

This _______ of the axonal membrane prevents effective passive conduction of electrical signals along the length of all but the shortest axons. To compensate for this deficiency action potentials for this deficiency, ______ __________ serve as a "booster system" that allows neurons to conduct electrical signals over great distances despite the poor passive electrical properties of axons.

leakiness;action potentials

What are the two reasons electrical potential are generated across the membrane of neurons-and, indeed, across the membranes of all cells?(hint: both conditions depend in turn on two different kinds of proteins in the plasma membrane)

-There are differences in the concentrations of specific ions across nerve cell membranes -These membranes are selectively permeable to some ions

An example of ____ ______ is a spike occurring in the axon of a spinal motor neuron.

Action Potential

A fundamental electrical signal that transiently abolishes the negative resting potential and makes the transmembrane potential positive.

Action potential

An activate response generated by the neuron and typically is a brief change from negative to positive in the transmembrane potential.

Action potential

_________ _______ are the basis of information transfer in the nervous system and are targets of many clinical treatments, including anesthesia.

Action potentials

Actively move selected ions against concentration gradients. Create ion concentration gradients

Active transporter

Actively move ions into or out of cells against their concentration gradients

Active transporters

The difference in the concentration of a substance between two areas

Concentration gradient

Differentiate the resting membrane potential and action potential

Differences: 1. -For resting potential, the electrical potential difference across the nerve when there is no nerve impulse conduction For action potential, The electrical potential difference across the nerve when there is nerve impulse conduction 1 For Resting Potential the potential which the neuron at rest (-70 mv) Potential at an excited state (+40 mv) 3. For resting potential: Membrane is more permeable to potassium For action potential: Membrane is more permeable to sodium Similarities: 1.-Both arise from ion fluxes brought about by the selective ionic permeability of nerve cell membranes 2.-Both are produced by ion channels

the net movement of anything from a region of higher concentration to a region of lower concentration

Diffusion

Neurons encode information via _____ ______ that result from transient changes in the resting membrane potential

Electrical signals

A Net flux of K+ moves from inside to the outside of a membrane, causing a potential to be generated that tends to impede further glow of K+. The flux of K+ from inside to outside balanced by opposing membrane potential. At this point, a _____ ______ will occur causing the membrane to be at resting potential

Electrochemical equilibrium

The electrical potential generated across the membrane at electrochemical equilibrium

Equlibrium pontential

What is a difference between action potentials, receptor potential, and sensory stimulus?

For action potentials, A stimulus is encoded in the frequency rather than in their amplitude For receptor potentials, amplitudes are graded in proportion to the magnitude of the sensory stimulus For synaptic stimulus, Amplitudes vary according to the number of synapses activated, the strength of each synapse, and the previous amount of synaptic activity

Consider a complex situation where both NA+ and K+ are unequally disturbed across the membrane as in figure 2.7 A. What would happen if 10 mM K+ and 10 mM NA were present inside, and 1. mMK and 10 mM Na were present outside?

If the membrane were permeable only to K +, the membrane potential would be -58 mV, If were permeable only to Na+, the pontential would be+58mV

Proteins that allow only certain kinds of ions to cross the membrane in the direction of their concentration gradients

Ion channels

The selective permeability of membranes is due largely to ____ ________

Ion channels

Upon entering the cell, the microelectrode reports a ____ _________, indicating that neurons have a means of generating a constant voltage across their membranes when at rest.

Negative potential

If the concentration of K+ on each side of this membrane is equal, then...

No electrical potential will be measured across it.

allowing liquids or gases to pass through it.

Permeable

Touching the skin activated nerve ending in Pacinian corpuscles(receptor mechanical distrubances of the skin) is an example of

Receptor potentials

Neurons generate a negative potential that can be measured by recording the voltage between the inside and outside of nerve cells

Resting membrane potential

being permeable to only certain molecules and not to all molecules

Selectively permeable

Use the Nerst equation to predict the resting membrane potential of the neuron regarding the concentration gradients of permeant ion

Solve a problem****

Activation of a synaptic terminal innervating a hippocampal pyramidal neuron causes a brief change in the resting membrane potential in the pyramidal neuron is an example of ____ ____. Hint this serves as the means of exchanging info in the complex neural circuits found in both the central and peripheral nervous systems.

Synaptic potentials

The electrical signal is associated with communication between neurons at synaptic contacts. They allow transmission of information from one neuron to another.

Synaptic potentials

Channels and transporters basically work against each other, and in doing so what do They generate?

The resting membrane potential, action potential, and they synaptic potentials and receptor potentials that trigger action potentials

Why are active potentials considered active responses?

They are generated by selective changes in the permeability of the neuronal membrane. Importantly, the amplitude of the action potentials of a given neuron are therefore said to be all or none aka they occur fully or not at all

Bc electrical signaling now occurs without any decrement indicates that active conduction via ____ _______ is a very effective way to circumvent the inherent weakness of neurons.

action potentials

The ion concentration gradients are established by proteins known as ____ _______________

active transporters

If the concentration of K a not the same on two sides, then...

an electrical potential will be generated

The progressive _________ in the amplitude of the induced potential change occurs because the injected current leaks out across the axonal membrane; accordingly, farther along the axon ____current is available to change the membrane potential

decrease; less

Displacement of a cell's membrane potential toward a more positive value than the resting potential

depolarization

Receptor potentials are due to the activation of sensory neurons by ____ ______> Give an example.

external stimuli; light, sound, heat

A stimulus is encoded in the ________ of action potentials rather than in their amplitude

frequency

Allow ions to diffuse down a concentration gradient, and are selectively permeable to certain ions

ion channels

When measuring the passive electrical properties of a nerve cell axon by determining the voltage change resulting from a current pulse passed across the axonal Membrane. If this current pulse is below the threshold for generating an action potential, then the ________ of the resulting potential change will decay with increasing stance from the site of current injection

magnitude

The membrane potential simply changes in proportion to the magnitude of the injected current. Such hyperpolarizing responses do not require any unique property of neurons and are therefore called ___ ____ _______

passive electrical responses

What are other was different types of electrical signals are produced?

the activation of synaptic contacts between neurons or by the actions of external of energy such as light ad sound on sensory neurons

The first type of electrical phenomenon can be observed as soon as the microelectrode is inserted through the .....

the membrane of the neuron

, the _______ potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.

threshold

Nerve cells generate a variety of electrical signals that _____ and _________ _______

transmit and store information

If the concentration of K+ in the inside compartment is ten times higher than the K+ concentration in the outside compartment, then the electric potential of the inside....

will be negative relative to that of the outside.