Term
| What is the stimulus that initiates action potential in the nervous system? |
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Definition
| A graded nonpropagating depolarization called a "receptor potential" or "generator potential" |
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Term
| Where does calcium serve to create the AP upstroke? |
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Definition
| In the SA node, smooth muscle cells, and others not discussed |
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Term
| What is the L-type Ca Channel? |
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Definition
| The main Ca2+ channel in the heart, also called dihydropyridine receptors. |
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Term
| How are calcium channel blockers used to treat hypertension? |
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Definition
| They cause small blood vessels to dilate. |
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Term
| What channels remain open during phase 4? |
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Definition
| The Ik1 channels (inward rectifiers). |
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Term
| What tissue has the shortest refractory period? |
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Definition
| Nerve and skeletal muscle |
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Term
| What ion helps to repolarize skeletal muscles? |
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Definition
| Cl- (high concentration OUTSIDE of the cell) |
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Term
| What type of muscle has gap junctions? |
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Definition
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Term
| What causes gap junctions to close? |
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Definition
| Very high intracellular calcium and protons. This can happen during heart attack. Really quite clever, because it quarantines the sick cells from the healthy ones. |
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Term
| What happens to people with multiple sclerosis? |
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Definition
| They have a degeneration of myelin. This disrupts conduction because myelin helps to increase cell diameter and Rm (reach) while decreasing Cm (charge storage ability). |
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