L8 Neurobiology✅

Where does the net difference in electrical charge occur in regards to membrane potential?

What causes large potential changes?

What is the rate of ion movement proportional to, and what determines that?

Graded potentials

How do ligand gated ion channels cause graded changes?

Inside and outside surfaces of the membrane

Miniscule changes in ionic concentrations

Driving force is determined by difference between membrane potential and equilibrium potential

Excitatory or inhibitory signals that occur in dendrites/cell bodies that vary in magnitude and duration based on strength of stimulus they receive that caused transient local changes over short distance

Being bound to by neurotransmitters leading to proportional changes in how many NTs bind

Electrotonic spread

Length constant

Threshold potential

What is required to activate Na channels?

EPSP

IPSP

Action potential

Local flow of electrical current through the neuronal membrane or other excitable tissues (like muscle fibers) in response to a change in membrane potential

Distance electrotonic current can spread

Membrane potential required to initiate action potential

Depolarization at about -55mv

Increases likelihood of reaching threshold (ligand gated Na+ channels)

Decreases likelihood of reaching threshold (ligand gated Cl- channels)

All or none long distance signals that maintain amplitude, magnitude, and duration for given cell that occurs in axons that is caused by opening/closing of voltage gated channels

What determines voltage gated Na channels opening?

What does intrinsic activation mean in regards to voltage gated Na⁺ channels?

Does depolarization of the membrane activate voltage gated K+ channels?

Absolute refractory period

Relative refractory period

From where to where do axon potentials spread?

Activation gate with voltage sensor that opens at threshold, and inactivation gate that closes from cytoplasmic side

Open in response to electrical signals but automatically stop conducting Na⁺ shortly afterward due to intrinsic inactivation, helping control the shape and timing of electrical impulses in cells.

Yes

Time between onset of AP until end of Na+ channel activation during which another AP cannot be triggered regardless of stimulus strength

Time during which stronger stimulus (more depolarizing current) is necessary to trigger AP due to hyperpolarization

Axon hillock to axon terminal

When Na+ flows into the neuron, what happens to the current?

What ensures unidirectional APs?

What encodes stimulation strength?

What’s necessary for high frequency APs?

What increases speed of AP conduction down axon?

Myelin sheath

Do signals travel faster through internodes or nodes of ranvier?

Positive current flows passively in both directions

Inactivation gate of voltage gated Na+ channels

AP frequency

Strong sustained depolarization

Myelination

Insulates axon, restricts action potentials to nodes of Ranvier, has current flow passively through internodes, and prevents ions from leaving cytoplasm increasing length constant by increasing rm

Internodes as signals jump along myelinated axons by saltatory conduction

Passive currents

Why does increasing axon diameter increase the speed of action potential conduction?

What are the different kinds of synapses?

When do voltage gated Ca2+ channels on the axon terminal open?

What causes

Decreases with distance from site of stimulation

Larger = faster

Because it reduces internal resistance, allowing depolarizing current to spread faster and farther, which speeds up action potential propagation.

Axon terminal, axon varicosities, en passant synapses, spine synapses

AP induced depolarization