Term
| Properties of Ion Channels |
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Definition
1. they conduct ions 2. they recognize and select specific ions 3. they open and close in response to specific electrical, mechanical, or chemical signals |
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Term
| Resting membrane potential is largely determined by which channels? |
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Definition
resting channels; channels that are selectively permeable to K+ (typically these channels are 100-fold more permeable to potassium than sodium) |
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Term
| What are the main types of channels? |
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Definition
1. voltage gated (regulated by changes in voltage) 2. ligand-gated (regulated by chemical transmitters) 3. mechanically gated (regulated by pressure or stretch) An individual channel is usually most sensitive to one type of signal. 4. resting channels - non-gated channels that are normally open in the cell at rest |
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Term
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Definition
| integral membrane proteins that span the lipid bilayer, providing a pathway for ions to cross the membrane |
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Term
| What makes up the plasma membrane? |
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Definition
The plasma membrane of all cells is about 6-8 nm thick, and consists of lipids and proteins. The surface is formed by a double layer of phospholipids. Embedded in this continuous lipid sheet are integral membrane proteins. Phospholipids have a hydrophilic head and a hydrophobic tail. The hydrophobic tails join to exclude water and ions, while the polar hydrophilic heads face the aqueous environment of the extracellular fluid and the cytoplasm. |
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Term
| What determines the ionic permeability properties of the plasma membrane? |
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Definition
| interactions of ions with water, the membrane lipid bilayer, and ion channels |
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