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BIOL 201
NUHS Phys CH4
Question | Answer |
---|---|
Movement of molecules from 1 location to another b/c of random thermal molecular motion; always occurs from a region of high concentration to low. | Diffusion |
Irregular motion of small particles suspended in a liquid or a gas | Brownian motion |
the amount of molecules crossing a surface in a unit of time | Flux |
difference between two one-way fluxes | Net flux |
state during which diffusion fluxes in opposite directions are equal; that is, the net flux equals zero | Diffusion equilibrium |
4 factors that affect the rate of diffusion: | temperature, mass of the molecule, surface area , and the medium or permeability coefficient |
number that defines the proportionality between a flux and a concentration gradient and depends on the properties of the membrane and the diffusing molecule | Permeability coefficient |
Give examples of "non-polar molecules" that are able to diffuse through lipid bilayers | Non-polar molecules: oxygen, carbon dioxide, urea, fatty acids, steroids |
small passage in plasma membrane through which certain small diameter molecules and ions can diffuse | Channel |
voltage difference between inside and outside of a cell | Membrane potential |
Name the most common ions that diffuse through channels and their normal direction with relation to cells. | Na, Cl, & Ca all "drive" into the cell, Na having the "highest net flux". K always "drives" out of the cell. |
the driving force across a plasma membrane that dictates whether an ion will move into or out of a cell; established by both concentration and electrical charge differences...Concentration has Greater effect than electrical pull. | Electrochemical gradient |
the process of opening or closing ion channels | Channel gating; (3) different types: chemically, mechanically, & voltage gated. |
chemical messenger molecule binds to protein channel and can open or close the channel | (ligand) or Chemically gated channel |
membrane ion channel that is opened or closed by deformation or stretch of the plasma membrane | Mechanically gated channel |
membrane ion channel opened or closed by changes in membrane potential (voltage) | Voltage gaged channel |
movement of molecules across membrane by binding to protein transporter; includes facilitated and active transport | Mediated transport |
integral membrane protein that mediates passage of molecule through membrane; also called carrier | Transporter |
system that uses a transporter coupled to an energy source to move ions or molecules across a membrane against an electrochemical difference; "uphill" | Active transport |
system using a transporter to move molecules "downhill" from high to low concentration; no energy required | Facilitated transport |
active transport in which chemical energy is transferred directly from ATP to transporter protein | Primary Active Transport |
during the movement of an ion along its normal electrochemical gradient(concentration & energy)it is coupled to the transport of another molecule which is moving "uphill" against its concentration. | Secondary Active Transport |
Most common ex: of primary active transport is the movement of Na & K ions across plasma membranes by Na+/K+ ATPase pumps | Na+/K+ ATPase pumps: For each ATP hydrolyzed, 3 Na ions pump out of a cell & 2 K ions pump in. |
KNOW Standard values of Na & K levels inside and outside of cells | Intracellular fluid: Na= 15mM, K= 150mM; Extracellular fluid: Na= 150mM, K= 5mM |
form of secondary active transport in which net movement of actively transported substance and molecule supplying the energy are in the same direction | Cotransport |
form of secondary active transport in which net movement of actively transported substance is in the opposite direction of the molecule supplying the energy | Countertransport |
net diffusion of water from region of higher water concentration (lower solute concentration) to region of lower water concentration (higher solute concentration) | Osmosis |
total solute concentration of a solution; what is the "normal" physiological level? | Osmolarity; 300mOsm |
one mole of solute ions and molecules | Osmol; 1 Osm |
membrane permeable to some substances (usually water) but not to others (some solutes) | Semipermeable membrane |
pressure that must be applied to a solution on one side of a membrane to prevent the net flow of water across the membrane. Force should always be = & opposite of Hydrostatic Pressure | Osmotic pressure |
dissolved substance that does not passively diffuse across a plasma membrane | Non-penetrating solute |
any solution that does not cause the change in cell size; has the same concentration of non-penetrating solutes as normal extracellular fluid | Isotonic |
solutions that have a non-penetrating solute concentration lower than that found in cells, therefore water moves by osmosis into the cells, causing them to swell | Hypotonic (hypo= big, cells swell) |
solutions containing > than 300 mOsm of non-penetrating solutes, cause cells to shrink as water diffuses out of the cell into the fluid with the lower water concentration | Hypertonic |
having the same total solute concentration as extracellular fluid | Isoosmotic |
having total solute concentration less than that of normal (300mOsm)extracellular fluid | Hypoosmotic |
having total solute concentration greater than normal extracellular fluid> 300mOsm | Hyperosmotic |
process in which intracellular vesicle fuses with plasma membrane, & its contents are released (exit) into the extracellular fluid | Exocytosis |
process in which plasma membrane folds into the cell, forming small pockets, membrane-bound vesicles, that "take in" particles from extracellular fluid | Endocytosis |
type of "fluid" endocytosis in which vesicles "drink" small amounts of extracellular fluid | Pinocytosis |
type of endocytosis in which vesicles "eat" large amounts of extracellular fluid | Phagocytosis |
type of endocytosis when certain molecules in the extracellular fluid bind to specific proteins (receptors) on the outer surface of the plasma membrane, the molecules are specifically taken in for cellular function or structure | Receptor-mediated endocytosis |
the space between adjacent cells of an epithelium through which some molecules diffuse as they cross the epithelium | Paracellular pathway |
crossing an epithelium by movement into an epithelial cell, diffusion through the cytosol of that cel, and exit across the opposite membrane | Transcellular pathway(more complicated) |
group of epithelial cells that secrete into the extracellular space hormones that then diffuse into the bloodstream | Endocrine gland |
cluster of epithelial cells cells specialized for secretion and having ducts that lead to an epithelial surface | Exocrine gland |
cluster of epithelial cells cells specialized for secretion and having ducts that lead to an epithelial surface |