A&P 1: Chapters 12 & 13 Practice Action Potential with animations and questions

Why does depolarization occur?

More Na+ diffuse into the cell than K+ diffuse out of it.

During depolarization, which of the following statements about voltage-gated ion channels is true?

Na+ gates open before K+ gates.

TRUE or FALSE The nerve impulse is an electrical current that travels along dendrites or axons.

TRUE

TRUE or FALSE The sodium-potassium pump is involved in establishing the resting membrane potential.

TRUE

Which of the following statements about the resting membrane potential is true?

The exterior of the cell has a net positive charge, and the interior has a net negative charge.

If demyelination occurs, why don't action potentials occur at regions of the axon that were previously myelinated? -These regions contain too high of a concentration of voltage-gated sodium channels to work appropriately. -A much thicker plasma membrane is present within these regions of the axon. -A much thinner plasma membrane is present within these regions of the axon. -These regions lack the appropriate concentration of voltage-gated sodium channels.

These regions lack the appropriate concentration of voltage-gated sodium channels.

A resting membrane potential of -70 mV indicates that the ________________. -negative ions are only present within the cytosol and are lacking in the extracellular fluid -charges lining the inside of the plasma membrane are negative compared to the charges lining the outside -negative ions will always move into a cell -positive ions outnumber the negative ions within the cytosol

charges lining the inside of the plasma membrane are negative compared to the charges lining the outside

Demyelinating diseases cause a(n) ______________ in the conduction velocity of action potentials. -decrease -increase

decrease

Action potentials occur ____________________________. -in the unmyelinated regions of an axon -in both unmyelinated and myelinated regions of an axon and the dendrites -in myelinated regions of an axon

in the unmyelinated regions of an axon

When voltage-gated sodium channels are open, sodium flows _____________ the neuron, making the inside of the cell more _______________. -out of; negative -out of; positive -into; positive -into; negative

into; positive

Graded potentials result from the opening of ________________. -leakage channels -voltage-gated channels -ligand-gated channels -ATP pumps

ligand-gated channels

Graded potentials result from the opening of ________________. -voltage-gated channels -ligand-gated channels -leakage channels -ATP pumps

ligand-gated channels

An inhibitory postsynaptic potential results from the opening of____________________. -chloride and/or sodium channels -sodium and/or potassium channels -potassium and/or chloride channels

potassium and/or chloride channels

Graded potentials are produced within the _______________________ segment of a neuron. -conductive -receptive -initial -transmissive

receptive

The following information best describes the _____________ phase of an action potential. • A membrane potential reading of +10 mV • Inactivated voltage-gated sodium channels • Open voltage-gated potassium channels -repolarization -resting -depolarization -hyperpolarization

repolarization

Normally, sodium and potassium leakage channels differ because ___________________. -sodium leakage channels always remain open, but potassium leakage channels must be specifically activated to open -sodium leakage channels are voltage-gated, but potassium leakage channels are ligand-gated -sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell -sodium leakage channels require ATP to transport ions, but potassium leakage channels do not

sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell