Term
| physical (or passive) processes |
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Definition
| diffusion, osmosis, facilitated diffusion, and filtration. |
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Term
| physiological (or active) processes |
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Definition
| active transport, endocytosis, and exocytosis. |
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Term
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Definition
| the tendency of atoms, molecules, and ions in a liquid or air solution to move from areas of higher concentration to areas of lower concentration (become more distributed - more diffuse). |
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Term
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Definition
| occurs because atoms, molecules, and ions are in constant motion. |
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Term
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Definition
| difference in concentration |
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Term
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Definition
| when concentration of substance becomes uniform throughout solution and there is no net movement. |
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Term
| requirements for diffusion |
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Definition
| 1. cell membrane is permeable to that substance, 2. concentration gradient exists such that the substance is at a higher concentration on one side of membrane or the other. |
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Term
| physiological steady state |
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Definition
| concentrations of diffusing substances are unequal but stable, more appropriate in reference to organisms |
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Term
| most important factors in diffusion rate |
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Definition
| distance, the concentration gradient, and temperature. |
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Term
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Definition
| movement that follows concentration gradient but uses membrane proteins as "carriers" , very important to ions and other larger water-soluble molecules |
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Term
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Definition
| moves molecules from higher to lower concentration BUT number of carrier molecules in cell membrane limits rate |
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Term
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Definition
| the movement of water across a selectively permeable membrane into a compartment containing solute that cannot cross the same membrane |
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Term
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Definition
| greater concentration of impermeant solute particles, the lower the water concentration of that solution, the greater osmotic pressure |
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Term
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Definition
| solutions with the same osmotic pressure as body fluids, cells do not change size in this solution |
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Term
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Definition
| solutions with a higher osmotic pressure than body fluids, if cells put into this solution there will be net movement of water by osmosis out of cell into surrounding solution - cells shrink |
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Term
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Definition
| solutions with lower osmotic pressure than body fluids, gain water by osmosis and swell or possibly even burst |
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Term
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Definition
| molecules are forced through membranes by this process |
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Term
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Definition
| commonly used to separate solids from water |
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Term
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Definition
| a passive process since gravity can be the applied force |
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Term
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Definition
| tissue fluid forms when water and dissolved substances are forced out through the walls of capillaries, but cells and large molecules are left inside |
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Term
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Definition
| movement against a concentration gradient from lower to higher concentration, requires energy derived from cellular metabolism |
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Term
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Definition
| uses carrier molecules within cell membrane that have binding sites that combine with specific particles being transported - triggers release of cellular energy - alters shape of carrier protein - "passenger" molecules can move through membrane |
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Term
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Definition
| moves molecules or other particles that are too large to enter a cell by diffusion or active transport; conveyed in a vesicle that forms from a section of the cell membrane |
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Term
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Definition
| pinocytosis, phagocytosis, receptor-mediated endocytosis |
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Term
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Definition
| intake of liquid droplets |
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Term
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Definition
| cell takes in tiny droplets of liquid, small portion of cell membrane indents, open end of tubelike part seals off and produces vesicle, sac detaches from surface and moves into cytoplasm, cell is able to take in water and particles dissolved in it |
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Term
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Definition
| intake of solids, often with the fusion of lysosomes which digest the material |
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Term
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Definition
| certain types of cells that can take in solid particles such as bacteria and cellular debris, ex. some white blood cells |
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Term
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Definition
| important line of defense against infection |
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Term
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Definition
| phagocyte encounters solid particle, particle attaches to cell membrane, portion of membrane projects outward surrounding particle and slowly draws it inside cell, part of membrane surrounding solid detaches forming vesicle, lysosome usually joins vesicle and lysosome enzymes decompose contents |
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Term
| receptor-mediated endocytosis |
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Definition
| moves specific kinds of particles into the cell |
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Term
| receptor-mediated endocytosis |
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Definition
| process involves protein molecules that extend through cell membrane and are exposed on its outer surface |
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Term
| receptor-mediated endocytosis |
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Definition
| protein-receptors present on cell membrane bind to specific ligands |
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Term
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Definition
| molecules that bind specifically to receptors |
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Term
| low-density lipoproteins (LDL) |
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Definition
| spherical particles where cholesterol molecules are synthesized in liver cells and packaged |
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Term
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Definition
| coating on LDL particle containing binding protein |
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Term
| receptor-mediated endocytosis |
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Definition
| molecules that can bind to receptor sites selectively enter cell; other types of molecules left outside |
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Term
| receptor-mediated endocytosis |
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Definition
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Term
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Definition
| reverse of endocytosis, expels the residue after lysosomal enzymes have digested solids brought in through phagocytosis |
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Term
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Definition
| allows cell to secrete material produced by cell, for example nerve cells use this to release neurotransmitters chemicals |
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Term
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Definition
| combines exocytosis and endocytosis to selectively and rapidly transport a substance/particle from one end of a cell to the other |
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Term
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Definition
| enables substances to cross barriers formed by tightly connected cells; occurs in normal physiology and in disease |
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Term
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Definition
| enables healthy immune system to monitor pathogens in small intestine, protecting against some forms of food poisoning |
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