Term
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Definition
| Passive movement of molecules in response to chemical or electrical forces |
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Term
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Definition
| Any method of transport of molecules across a membrane that does not require energy |
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Term
| 3 Types of passive transport |
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Definition
| Simple diffusion, facilitated diffusion and osmosis |
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Term
| 3 factors that affect the rate of passive transport |
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Definition
Magnitude of driving force
Membrane surface (surface area)
Permeability |
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Term
| 4 factors that affect the permeability of a membrane to simple diffusion |
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Definition
Lipid soluble
size of solute
temperature (high temps cause molecules to move faster)
membrane thickness |
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Term
| What can get through the cell membrane w/o help? |
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Definition
| water, gases, lipids, small polar covalent bonds (CO2) |
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Term
| What can't get through the cell membrane w/o help? |
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Definition
| Glucose, amino acids, and ions(anything w/ a charge) |
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Term
| What is the process of facilitated diffusion? |
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Definition
| Transmember proteins bind a molecule on one side of the membrane and undergo a conformation change and release it on the other side of the membrane. It's specific for substances like glucose and amino acids. |
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Term
| What 4 factors can affect facilitated diffusion? |
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Definition
-Transport rate of carrier or channels (some carriers are faster than others)
-Number of binding sites or # of carriers/channel proteins
-Concentration or electrochemical gradient of substance
-Cells can regulate the activity of individual carriers or channels and/or the number of carriers or channels that are present |
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Term
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Definition
| Passive diffusion of water from an area of higher water concentration (low solute) to low water concentration (high solute). |
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Term
| What are 2 characteristics of active transport that differentiate it from passive transport? |
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Definition
-Requires energy
-Directional flow of molecules goes up an electrochemical gradient - From low -> high |
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Term
| Define primary active transport. |
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Definition
| Active transport of molecules utilizing a protein (pump) that uses ATP as the energy source. |
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Term
| What is the significance of the Na+/K+ pump? |
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Definition
| It pumps sodium out of cell and potassium in the cell. |
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Term
| Define secondary active transport. |
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Definition
| Active transport of molecules utilizing a carrier that uses a concentration gradient or electrochemical gradient as a source of energy. |
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Term
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Definition
| Occurs in secondary active transport. It is a carrier-mediated transport by which two transported substances move in the same direction. |
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Term
| Define countertransporters. |
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Definition
| Secondary active transport by which 2 transported substances move in opposite directions. |
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Term
| What 4 factors affect the rate of active transport? |
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Definition
-Nature of the pump (some pumps are faster than others)
-Concentration of substances to be transported
-Size of electrochemical gradient
-# of pumps |
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Term
| Why is isotonic saline given to patients in infusions when blood has been lost and whole blood is unavailable? |
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Definition
| Saline solution matches the total solute concentration of the ECF, so that the cell volumes won't be altered (cell wont swell or shrink) |
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Term
| Why doesn't the ECF become hypertonic when glucose is added to an isotonic solution? |
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Definition
| Glucose is able to move through the cell membrane w/ facilitated transport, so it doesn't affect the cell volume. |
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Term
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Definition
| Total concentration of solute particles in a solution. |
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Term
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Definition
| 2 solutions having the same osmolarity |
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Term
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Definition
| A solution having an osmolarity that is higher than another. |
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Term
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Definition
| A solution with a lower osmolarity than another. |
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Term
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Definition
| An indirect measure of a solute's concentration, expressed in ordinary units of pressure. |
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Term
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Definition
| A solution that will not alter cell volume. |
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Term
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Definition
| A solution that draws water out of a cell, causing the cell to shrink |
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Term
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Definition
| A solution that causes water to enter a cell causing the cell to swell. |
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Term
| What are 3 types of endocystosis? |
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Definition
| phagocytosis, pinocytosis, and receptor-mediated endocytosis. |
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Term
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Definition
| Uptake of material into a cell via vesicles that pinch off from the plasma membrane; enables macromolecules and larger particles to enter cells. |
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Term
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Definition
| Process by which a cell engulfs microorganisms, abnormal cells, and foreign particles present in blood and tissues. |
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Term
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Definition
| A form of endocytosis in which a cell takes up fluid and dissolved molecules via endocytotic vesicles that pinch off the plasma membrane. |
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Term
| Define receptor-mediated endocytosis. |
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Definition
| A form of endocytosis in which endocytotic vesicles contains receptors that recognize and bind specific molecules in the extracellular fluid; enables cells to selectively take up certain molecules. |
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Term
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Definition
| Transport of material out of a cell via vesicles that fuse w/ the plasma membrane; involved in the cellular secretion of hydrophilic molecules. |
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Term
| What are the 3 driving forces acting across the cell membrane? |
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Definition
| Chemical, electrical and electrochemical. |
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Term
| Define chemical driving force. |
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Definition
| Difference in energy due to a concentration gradient that causes a molecule to move from high concentration to low. |
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Term
| Define electrical driving force. |
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Definition
| Difference in energy due to a separation of charge that acts to move ions from high energy to low energy. |
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Term
| Define electrochemical driving force. |
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Definition
| The sum of electrical and chemical driving forces. |
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Term
| Define resting membrane potential. |
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Definition
| The voltage that exists across a cell membrane when the cell is not transmitting electrical signals; polarity is such that the inside of the cell is negative w/ respect to the outside. |
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Term
| What determines resting membrane potential? |
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Definition
| Passive processes establish it and active processes maintain it. |
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Term
| Define equilibrium potential. |
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Definition
| The membrane potential at which the electrical driving force is equal and opposite to the chemical driving force, giving an electrochemical driving force of zero. |
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Term
| What is the equilibrium potential of sodium and potassium. |
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Definition
| Sodium is +60mv. Potassium is -90mv. Sodium has a direction of in towards the cell due to the fact that the more sodium that enters the cell, the more the outside of the cell will get more and more negative. It eventually causes the outside to get more negative than the inside, the inside then starts to pull the sodium out the cell. Potassium has a direction of away from the cell due to the fact that there's more potassium inside the cell than outside. The more the potassium leaves the cell, the more negative the inside of cell get. This negative charge inside attracts the potassium to come back inside the cell. |
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