Term
| What will hyperkalemia do to membrane excitability and why? |
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Definition
| The higher levels of K inside the membrane make the inside of the cell less negative, bringing it closer to threshold and hence more excitable |
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Term
| What will hypokalemia do to membrane excitability and why? |
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Definition
| Lower levels of K inside the cell make the inside of the cell more negative, therefore making it further from threshold and less excitable |
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Term
| How does cardioplegia work? |
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Definition
| Cardioplegia is very high in K [15-40]. This means more K in the cell, which makes the inside less negative and moves the cell past threshold; Na channels open up and an AP is initiated; the Na channels then move to their inactive state; however, because there is so much K outside the cell, the K channels that usually open up to pump K outside so that membrane potential can return to normal do not open, and the Na channels remain in the inactivestate indefinitely |
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Term
| What does hypercalcemia do to threshold? |
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Definition
| It makes for a higher threshold (less negative) because more Ca is on the cell membrane repelling similarly charged Na from going into the cell--the cell is LESS EXCITABLE |
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Term
| What does hypocalcemia do to the threshold and cell excitability? |
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Definition
| Less Ca on the membrane repelling the Na ions means the cell's threshold is lower (more negative) and THE CELL IS MORE EXCITABLE |
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Term
| What are 2 EKG signs of hyperkalemia? |
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Definition
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Term
| What does hypermagnesemia do to NMB agents? |
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Definition
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Term
| What is the normal resting membrane potential for ventricular myocytes? |
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Definition
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Term
| What is the normal resting membrane potential for nerve cells? |
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Definition
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Term
| Which electrolyte is responsible for resting membrane potential? |
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Definition
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Term
| What electrolyte is responsible for membrane threshold? |
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Definition
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Term
| Why does alkalosis cause s/s of hypocalcemia? |
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Definition
| Normally, H+ binds to plasma proteins. However, during times of alkalosis, the H+ is released in order to balance pH. Therefore, the proteins bind to the iCa, causing a functional hypocalcemia despite a normal total Ca |
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Term
| How does hyperventilation lead to s/s of hypocalcemia? |
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Definition
| Hyperventilating blows off CO2, causing alkalosis. This leads to the H+ thats normally bound to proteins to release; the now unbound proteins bind to the iCa, leading to a functional (but not total) hypocalcemia |
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Term
| Give 7 ways to treat hyperkalemia |
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Definition
| 1. Bicarb 2. Hyperventilate 3. Insulin/glucose 4. Beta agonists 5. Dialysis 6. Kayexelate 7. Calcium |
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