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deleted634258
Hello forum members,
So I'm reading this chapter on heart physiology and I have a question on 2 paragraphs I came across. The text is as follows:
"Excess potassium in the extracellular uids causes the heart to become dilated and accid and also slows the heart rate. Large quantities of potassium also can block conduction of the cardiac impulse from the atria to the ventricles through the A-V bundle. Elevation of potassium concentration to only 8 to 12 mEq/L—two to three times the normal value—can cause severe weakness of the heart, abnormal rhythm, and death.
These effects result partially from the fact that a high potassium concentration in the extracellular fluids decreases the resting membrane potential in the cardiac muscle fibers, as explained in Chapter 5. That is, high extracellular fluid potassium concentration partially depolarizes the cell membrane, causing the membrane potential to be less negative. As the membrane potential decreases, the intensity of the action potential also decreases, which makes contraction of the heart progressively weaker."
This is where I'm lost:
1. Does the extracellular potassium cause the cell to be less negative by flowing into the cell, forcing itself inside?
2. The last sentence says that the membrane potential decreases, but doesn't the potential increase if the membrane potential becomes less negative?
Can someone maybe explain this text?
Thanks so much in advance.
So I'm reading this chapter on heart physiology and I have a question on 2 paragraphs I came across. The text is as follows:
"Excess potassium in the extracellular uids causes the heart to become dilated and accid and also slows the heart rate. Large quantities of potassium also can block conduction of the cardiac impulse from the atria to the ventricles through the A-V bundle. Elevation of potassium concentration to only 8 to 12 mEq/L—two to three times the normal value—can cause severe weakness of the heart, abnormal rhythm, and death.
These effects result partially from the fact that a high potassium concentration in the extracellular fluids decreases the resting membrane potential in the cardiac muscle fibers, as explained in Chapter 5. That is, high extracellular fluid potassium concentration partially depolarizes the cell membrane, causing the membrane potential to be less negative. As the membrane potential decreases, the intensity of the action potential also decreases, which makes contraction of the heart progressively weaker."
This is where I'm lost:
1. Does the extracellular potassium cause the cell to be less negative by flowing into the cell, forcing itself inside?
2. The last sentence says that the membrane potential decreases, but doesn't the potential increase if the membrane potential becomes less negative?
Can someone maybe explain this text?
Thanks so much in advance.