Cellular Neurobiology Exam 2

______ is the difference in charge between 2 points

voltage

When voltage is quantified, it is defined as ______

potential

______ is the movement of positive charge from one place to another

current

Rate of movement of current is measured in ______

amperes

______ is the opposition to flow of electric current

resistance

Resistance is measured in ______

Ohms

_______ is the inverse of resistance and the ease with which current can flow from one place to another

conductance

Units of conductance are _____

Siemens

______ is the capability for an ion to move across the membrane

permeability

Voltage is the force responsible for ________

current

The _____ of voltage is related to the electromotive force inducing current

magnitude

______ is a technique where an experimenter holds Vm at a desired potential and measures ionic currents across the membrane

voltage clamp

_______ is the net movement of positive charge into the cell

inward current

______ is the net movement of positive charge out of the cell

outward current

In ______ summation, inputs are summed over time

temporal

In _____ summation, inputs are summed from multiple inputs

spatial

Passive current flow induces change in neighboring membrane potential but the _____ of potential decreases with distance

magnitude

______ is the distance at which passive electrical potential magnitude decreases to 37% of its initial value

length constant

Sodium channel refractory period ensures ______ action potential propagation

unidirectional

To increase conduction velocity, one can reduce the resistance of the _____

axoplasm

To increase conduction velocity, one can increase resistance of the ______

membrane

______ is propagation of action potentials along myelinated axons from one node of Ranvier to the next

saltatory conduction

Saltatory conduction has a faster ______ than with unmyelinated axons

velocity

Myelination of axons increases the _________

length constant

Axon contains sodium and potassium channels to ______ an action potential along its length

regenerate

Ion channels are composed of ______

transmembrane proteins

Nearly all ion channels can open and close in response to a _______

stimulus

In an ion channel’s _____, the channel is an open pore that allows the passage of ions

open state

In an ion channel’s ______, the channel is a closed pore that can be opened upon a new stimulus

closed state

In an ion channel’s ______, the channel is a closed pore that cannot be reopened until a new physical state is achieved

inactivated state

True or False: Not all ion channels have an inactivated state

true

The inactivated state of sodium channels is responsible for an action potential’s ______

refractory period

Movement between states is called ______

gating

States represent specific, semi-stable _____ of a channel protein

conformations

______ is the rate at which a channel moves between states

kinetics

True or False: The behavior seen with macroscopic current is different from that of microscopic current

false

Summed channel behavior yields _______ current

macroscopic

Probability of sodium and potassium channel opening increases linearly at ______

threshold potential

Populations of channels respond ______

stochastically

Specific properties of different types of ion channels arise from different ______ structures

protein

An ion channel is a functional channel composed of ______

subunits

Sometimes an ion channel has a ______ subunit that affects function

auxiliary beta

All ion channels form a _____ that is selective for certain ions

pore

Ion channels have specialized _____ that affect channel properties

domains

Hydrated potassium moves into a pore’s ______

water filled cavity

_______ groups from the amino acid backbone lining the pore allow energetically favorable interactions between unhydrated potassium ions and oxygen atoms

carbonyl

When potassium ions are _____, they move into the pore

dehydrated

True or False: Sodium ions are capable of entering potassium ion channels

true

Electrostatic _____ of potassium ions helps push them through an ion channel

repulsion

True or False: Selectivity of sodium channels is similar to that of potassium channels

true

______ charges near the external pore of a sodium channel attract sodium

negative

True or False: Sodium is fully hydrated and moves to the internal hydrated pore

false

Electrostatic interactions in the selectivity filter of a sodium channel helps increase ion _______

flux

Basic residues _________ in specific transmembrane helices move in response to membrane potential

arginine and lysine

Movement of voltage sensor affects the channel pore via a _________

linker domain

Binding of ligand molecules induces a _____ change resulting in an open pore

conformational

________ are ligands that bind to the extracellular side

neurotransmitters

______ binds to extracellular ligand binding domains

glutamate

TRP channels open in response to _______

heat

Piezo (mechanosensitive channel) has blade structures that serve as _____ to open the channel when curved membranes are physically flattened

levers

Most venoms are ______ that bind to channels and change their properties

peptides

Scorpion toxin binds to voltage-gated sodium channels and slows inactivation, prolonging _______ (pl) and paralyzing prey

action potentials

Ion channels play a role in physiology and ______

behavior

_______ are diseases that have been linked to specific mutations within genes that code for ion channels

channelopathies

Inherited erythromelalgia mutations in a certain gene cause voltage-dependent activation shift to more ______ potentials

negative

What are the three types of ion channel gating? (You only need to say the first word (exclude ‘gating’). Separate by commas.)

voltage, ligand, and physical