Question

The EKG is hooked up, and Mr. M's trace looks very abnormal. His heart rate is low. The T wave, which indicates repolarization of the ventricles, is unusually large and pointed and the QRS wave, which indicates the depolarization impulse’s passage through the ventricles, is widened or slowed. "That's a classic EKG for hyperkalemia (high blood potassium)!" The doctor gives Mr. M an injection of calcium gluconate. Calcium ions block the Na+ channels on nerve and muscle cells. How will this help counteract the effects of high blood K+? g

Answer 1

Answer:

This question lacks options, options are: Mr. M's cells are depolarizing too easily. Blocking Nat channels will make it harder for them to depolarize, bringing their sensitivity back to normal O Mr. M has too little K* leaving his cells, so we need to block the Nat channels so the Kt channels can stay open and his cells can repolarize properly. Mr. M has too little K* leaving his cells, so we need to block the Nat channels so the Na /K+ ATPase can move Kt out of the cell effectively O Blocking Na* channels cannot help- it will only make his cells fire less, and he already has a weak heartbeat. Mr. M's cells are not repolarizing properly. Blocking Nat channels will help them repolarize normally, bringing their resting potential back to normal.

The correct answer is ''Mr. M's cells are depolarizing too easily. Blocking Na+ channels will make it harder for them to depolarize, bringing their sensitivity back to normal.''

Explanation:

Calcium administration is an emerging treatment modality aimed at restoring the transmembrane electrical gradient of cardiac myocytes. It probably achieves this goal by reducing the resting membrane potential of cells. Calcium antagonizes the effect of hyperkalemia on cardiac conduction, that is, it antagonizes the effects of K on the heart. Its onset of action is immediate, in a few minutes. Calcium gluconate antagonizes the excitability of the cardiac membrane, that is, it decreases the excitability of the membrane and it does not affect serum levels, it is generally accepted that calcium should be administered when there are ECG changes associated with hyperkalemia.