Term
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Definition
| -Does not requiere cellular energy (diffusion, facilitated diffusion, osmosis and filtration) |
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Term
Diffusion
(a passive mechanism) |
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Definition
-the process by which molecules or ions scatter or spread spontaneosly from regions where they are in higher concentrations towards regions where they are in lower concentrations
-concentration gradient: difference in concentration
-Equilibrium: the state which molecules are uniformly distributed
-example: gas |
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Term
Facilitaed Diffusion
(a passive mechanism) |
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Definition
| -Substances that are not able to pass through the lipid bilayer need the help of membrane proteins to get across |
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Term
Osmosis
(a passive mechanism) |
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Definition
-Special case of diffusion, whenever water molecules diffuse from a region of higher water concentration to a region of lower water concentration
-osmotic pressure: the ability of osmosis to generate enough pressure to lift a volume of water
-ex: the lower the water concentration of that solution , the greater the osmotic pressure |
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Term
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Definition
-isotonic: any solution that has the same osmotic pressue as body fluids
-hypertonic: solutions with higher osmotic pressure than body fluids
-hypotonic: solutions having lower osmostic pressure than body fluids |
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Term
Filtration
(a passive mechanism) |
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Definition
-Forces molecules through membranes
-commonly used to seperate solids from water
-Hydrostatic Pressure: Pressure in body hitting veins
-edema: excess of tissue fluid |
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Term
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Definition
- Particles moving through membranes from a region of lower concentration to a region of higher concentration
-Needs energy from ATP |
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Term
Endocytosis
(an active mechanism) |
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Definition
-Molecules or other particles that are too large to enter a cell by diffusion, facilitated diffusion are conveyed within a vesicle formed from a section of the cell membrane
**Happens in 3 ways
-Pinocytosis: "cell drinking"
-Phagocytosis: "cell eating"
Receptor-Mediated endocytosis: moves a very specific kind of particle into the cell |
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Term
Exocytosis
(an active mechanism) |
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Definition
| -Secretes a substance stored in vesicle from the cell |
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