BIOs 224 PRACTICE EXAM 2

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BIOs 224 PRACTICE EXAM 2

• Chloride

–Answer The resting membrane potential primarily depends on the plasma membrane permeability of all of the following ions EXCEPT

• resting membrane potential

–Answer The electrical charge difference between the in- side and outside of the plasma membrane in excitable cells is referred to as the resting potential.

• Action potentials are conducted from one cardiac cell to another

–Answer How is action potential propagation different in cardiac muscle cells than in skeletal muscle cells?

• Depolarization

–Answer Na+ diffuses into the cell

• Plataeu

–Answer Ca++ diffuses into the cell

• Repolarization

–Answer K+ diffused out of the cell; The refractory period of cardiac muscle cells is extended due to a delayed

• Potassium

–Answer At rest, what ion is abundant inside of the cardiac cell membrane, helping to establish the resting membrane potential?

• chloride

–Answer 1 / 2

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The resting membrane potential primarily depends on the plasma mem- brane permeability of all of the following ions EXCEPT

• List in order the events of an action potential of a ventricular cardiac muscle cell

–Answer

• Voltage-gated Na+ channels open
• Influx of Na+ causes more Na+ channels to open, depolarization
• Na+ channels close as membrane potential peaks +30 mV
• Ca++ enters through slow calcium channels; creates plateau
• Ca++ channels close, K+ channels open; repolarization
• Electrical changes

–Answer What controls the opening of the ion channels in cardiac muscle cells during phases of the action potential?

• sodium channels open

–Answer What is the first step in an action potential in a cardiac muscle cell?

• Potassium channels begin to open

–Answer Which occurs during the repolarization phase of a cardiac muscle cell but not in a skeletal muscle cell?

• sodium into

–Answer Depolarization of the cardiac muscle cell is primarily due to the diffusion of the cell.

• Gap junctions

–Answer What allows for cell-to-cell conduction in cardiac muscle tissue?

• voltage

–Answer Electrical changes across the membrane cause the opening and clos- ing of -gated ion channels..

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