Cell Potential

The "all or none law" refers to the observeration that an action potential

• will dimmish to near zero when transmitted won a ling axon.

• is conducted more rapidly down the axon as it reaches the axon terminal.

• is produced whenever the membrane potential reaches threshold.

What are tiny gaps in the myelin sheath at which the action potential is relayed along the neuron?

• schwann cells

• merkel disks

• golgi bodies

• nodes of Ranvier

Once the neuron is active, then the permeability of the membrane changes and allows an influx of ___________ ions causing______________

• negative; hyperolarization

• negative; depolarization

• positive; depolarization

• positive; hyperpolarization

What ion enters aq neuron causing depolarization of the cell membrane?

• chloride

• sodium

• poatssium

• phosphate

Tags

NGSS.HS-LS1-3

What keeps an action potential on an axon from stimulating another action potential that will travel back toward the cell body?

• refractory period

• relative refractory period

• absolute refractory period

• potential period

What is the resting membrane potential of neurons maintained by?

• Chemically gated Na+ Channels 

• Chemically gated K+ channels 

• Na+/K+ ATPase pump 

• Na+/H+ ATPase pump 

Repolarisation of an activated neuron does NOT include:

• Opening of voltage-gated Na⁺ channels

• Opening of voltage-gated K⁺ channels

• Shifting membrane potential towards resting levels

• Inactivation of voltage-gated Na⁺ channels

At threshold (-60mV), voltage-gated K⁺ channels are closed and voltage-gated Na⁺ channels open.

• True

• False

Local Potentials

• Depolarise the membrane to the same level (+30 mV) each time

• Depolarise or hyperpolarise the membrane to different levels

• Propagate down the axon

• Associate with voltage-gated ion channels

What is the standard cell potential for a galvanic cell composed of a zinc electrode in a 1 M ZnSO4 solution and a copper electrode in a 1 M CuSO4 solution?

• A) 0.34 V

• B) 1.10 V

• C) 0.76 V

• D) 1.50 V