Human Anatomy Quiz 16: Electrical Signals

depolarization, repolarization

What phases do action potentials have?

all or nothing

What kind of response is present until the threshold is reached?

resting potential

What is a membrane at before an action potential begins?

leakage gates

What is the only movement of ions through?

closed, -70mV

Are the sodium and potassium gated channels opened or closed at rest? What is the resting potential of the membrane at rest?

strength of the stimulus

What does the number of channels opened depend on?

the inside of the neuron becomes slightly positively charged, because of all the sodium flowing in

What happens to the inside of the neuron when enough sodium channels are opened? Why?

many sodium channels are open, positive, positive feedback

What occurs in depolarization? What is the charge inside of the cell due to this? What kind of feedback is involved here?

the more sodium gates that open

The more positive the inside of a cell becomes during depolarization…

potassium, sodium

Which gates are opened during repolarization? Which gates close?

potassium, more negative, potassium gates

During undershoot, a lot of what type of ion leaves the cell? Does this result in the cell becoming more negative or more positive than the resting potential? What gates close to conclude the refractory period?

sodium potassium pumps must restore original ion concentration gradient and resting potential

What must occur for an action potential to be propagated?

when action potential travels all the way down the axon

What is propagation?

gated channels in the section open, continuous conduction

What occurs when one segment of the membrane depolarizes the flood of sodium? What is this process known as?

only the nodes of Ranvier must depolarize

Why is conduction in the myelinated axons faster?

node to node, saltatory conduction

What does an impulse jump from in myelinated axons? What is this called?

axon terminal, synapse

What must an action potential reach before it must be passed onto the next cell? What is it passed across?

direct connections between cells, flow from one cell to another

What are gap junctions? What do they allow ions to do?

electrical synapse

What is it called when ions flow from one cell to another?

no

Do most cells have direct connections for ion flow?

synaptic cleft

What is the space between cells called?

chemical transmitter

What is required to cross the gap between neurons?

chemical synapse

What is it called when a chemical transmitter crosses a gap between neurons?

axon terminal of presynaptic neuron

Where does an action potential arrive?

open voltage gated calcium channels

What does the depolarization at the axon terminal of the presynaptic neuron do?

cause exocytosis of synaptic vesicles that are filled with neurotransmitters

What does the influx of calcium from voltage gated calcium channels do?

cleft, receptors on postsynaptic neuron, ligand-gated ion channels, to let ions in

What does a neurotransmitter diffuse across? What does it bind to? What kind are these typically? Why do they open?

depolarization

If channels are for sodium, what will happen to the membrane?

hyperpolarization

If channels are for potassium or chlorine, what will happen to the membrane?

action potential begins

Once the threshold is reached, what occurs?

stimulatory, inhibitory

Neurotransmitters can be… (2 things)

depolarize the membrane and cause an action potential

What do stimulatory neurotransmitters do?

hyperpolarize the membrane making it harder for an action potential to occur

What do inhibitory neurotransmitters do?

diffusion, degradation by enzyme, cellular reuptake

How is a neurotransmitter removed? (3 ways)