| 单词 | concentration gradient |
| 例句 | Therefore, water will diffuse down its concentration gradient, crossing the membrane to the side where it is less concentrated. Concepts of Biology 2013-04-25T00:00:00Z When the membrane is at rest, K+ ions accumulate inside the cell due to a net movement with the concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z Sometimes cells transport materials against a concentration gradient, from an area of low concentration to an area of higher concentration. Miller & Levine Biology 2018-01-01T00:00:00Z By doing this, a concentration gradient is established where glucose levels are higher in the blood than in the cells. Anatomy and Physiology 2013-06-19T00:00:00Z Many crystals contain defects whose concentration varies across the crystal; the resulting concentration gradient breaks the macroscopic symmetry of the crystal, causing residual piezoelectricity and pyroelectricity3. Temperature-dependent polarization in a non-polar crystal 2019-11-17T05:00:00Z This diffusion of water through the membrane—osmosis—will continue until the concentration gradient of water goes to zero. Concepts of Biology 2013-04-25T00:00:00Z The cell possesses potassium and sodium leakage channels that allow the two cations to diffuse down their concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z Now there is a concentration gradient between the inside and outside of the thylakoid. Miller & Levine Biology 2018-01-01T00:00:00Z However, these cells must also pump ions against their concentration gradient, so you will find of large numbers of mitochondria, although fewer than in the PCT. Anatomy and Physiology 2013-06-19T00:00:00Z When exposed to a concentration gradient of glucose—more sugar in one spot than another—the polymersomes absorb the sugar molecules and break them down. Drug-Carrying "Nanoswimmers" Could Slither Past the Brain's Cellular Defenses 2017-08-07T04:00:00Z In solutions of more than one substance, each type of molecule diffuses according to its own concentration gradient. Concepts of Biology 2013-04-25T00:00:00Z Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z It serves as a solvent in the cell cytoplasm and exterior, and like other molecules, it moves down its concentration gradient by osmosis. [Perspective] A SWELL Channel Indeed 2014-05-08T18:25:46.480Z As is the case with other substances, drugs may be both filtered and reabsorbed passively along a concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z The smokestack technology applies this principle to a carbon dioxide concentration gradient. New efforts aim to turn smokestack pollution into usable energy 2013-08-26T18:23:19Z Many factors can affect the rate of diffusion, including concentration gradient, the sizes of the particles that are diffusing, and the temperature of the system. Concepts of Biology 2013-04-25T00:00:00Z In the upper component, the dialysate has a higher solute concentration than the blood, which allows the urea to diffuse to the lower dialysate down its concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z Many factors can affect the rate of diffusion, including concentration gradient, size of the particles that are diffusing, temperature of the system, and so on. Biology for AP Courses 2022-06-09T00:00:00Z Figure 3.7 Osmosis Osmosis is the diffusion of water through a semipermeable membrane down its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Fructose diffused because of the pore specificity of the semipermeable membrane, not because of its concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z The combined gradient that affects an ion includes its concentration gradient and its electrical gradient. Concepts of Biology 2013-04-25T00:00:00Z In the upper component, the dialysate has a lower solute concentration than the blood, which allows the urea to be separated via active transport down the concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z A hydrogen ion gradient across the membrane establishes a concentration gradient and not an electrical gradient, thus assisting during the electron transport chain. Biology for AP Courses 2022-06-09T00:00:00Z During active transport, ATP is required to move a substance across a membrane, often with the help of protein carriers, and usually against its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Removing the signals will reestablish the concentration gradient for the signal, allowing them to quickly diffuse through the intracellular space if released again. Biology for AP Courses 2022-06-09T00:00:00Z In secondary transport, energy from primary transport can be used to move another substance into the cell and up its concentration gradient. Concepts of Biology 2013-04-25T00:00:00Z In the upper component, the dialysate has a lower solute concentration than the blood, which allows the urea to diffuse to the lower dialysate down its concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z Neurons and muscle cells maintain a high concentration gradient of potassium ions across the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z A concentration gradient is the difference in concentration of a substance across a space. Anatomy and Physiology 2013-06-19T00:00:00Z This alone accumulates a small electrical charge, but a big concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z As the electron passes along these proteins, energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space. Concepts of Biology 2013-04-25T00:00:00Z The attracting chemotactic agent alters the frequency of turning as the organism moves directly toward the source, following the increasing concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z When K+ leaves the cell, obeying its concentration gradient, that effectively leaves a negative charge behind. Biology for AP Courses 2022-06-09T00:00:00Z Ion channels are pores that allow specific charged particles to cross the membrane in response to an existing concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z So at rest, there is a large concentration gradient for Na+ to enter the cell, and there is an accumulation of negative charges left behind in the cell. Biology for AP Courses 2022-06-09T00:00:00Z A physical space in which there is a different concentration of a single substance is said to have a concentration gradient. Concepts of Biology 2013-04-25T00:00:00Z Each separate substance in a medium, such as the extracellular fluid, has its own concentration gradient, independent of the concentration gradients of other materials. Biology for AP Courses 2022-06-09T00:00:00Z Diffusion is a process in which transport is driven by a concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z The Na+ concentration becomes high outside the gustatory cells, creating a strong concentration gradient that drives the diffusion of the ion into the cells. Anatomy and Physiology 2013-06-19T00:00:00Z The concentration gradient of water across a membrane is inversely proportional to the concentration of solutes; that is, water moves through channel proteins called aquaporins from higher water concentration to lower water concentration. Biology for AP Courses 2022-06-09T00:00:00Z A physical space in which there is a range of concentrations of a single substance is said to have a concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z This lack of a concentration gradient in which there is no net movement of a substance is known as dynamic equilibrium. Biology for AP Courses 2022-06-09T00:00:00Z While diffusion will go forward in the presence of a concentration gradient of a substance, several factors affect the rate of diffusion. Biology for AP Courses 2022-06-09T00:00:00Z This characteristic puzzled researchers for a long time because the Cl– ions are actually flowing down their concentration gradient when transported out of cells. Anatomy and Physiology 2013-06-19T00:00:00Z Extent of the concentration gradient: The greater the difference in concentration, the more rapid the diffusion. Biology for AP Courses 2022-06-09T00:00:00Z Therefore, a concentration gradient forms in which hydrogen ions diffuse out of the matrix space by passing through ATP synthase. Biology for AP Courses 2022-06-09T00:00:00Z In filtration, material moves according to its concentration gradient through a membrane; sometimes the rate of diffusion is enhanced by pressure, causing the substances to filter more rapidly. Biology for AP Courses 2022-06-09T00:00:00Z Water has a concentration gradient in this system. Biology for AP Courses 2022-06-09T00:00:00Z The absence of ions in the secreted mucus results in the lack of a normal water concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Thus, water will diffuse down its concentration gradient, crossing the membrane to the side where it is less concentrated. Biology for AP Courses 2022-06-09T00:00:00Z This effect makes sense if you remember that the solute cannot move across the membrane, and thus the only component in the system that can move—the water—moves along its own concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z A concentration gradient exists that would allow these materials to diffuse into the cell without expending cellular energy. Biology for AP Courses 2022-06-09T00:00:00Z When dealing with ions in aqueous solutions, a combination of the electrochemical and concentration gradients, rather than just the concentration gradient alone, must be considered. Biology for AP Courses 2022-06-09T00:00:00Z During passive transport, materials move by simple diffusion or by facilitated diffusion through the membrane, down their concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z One method is through secondary active transport in which the transport takes place against the glucose concentration gradient. Biology for AP Courses 2022-06-09T00:00:00Z As the protons are driven down their concentration gradient through ATP synthase, ATP is generated from ADP and inorganic phosphate. Biology for AP Courses 2022-06-09T00:00:00Z Increasing the concentration gradient at this point will not result in an increased rate of transport. Biology for AP Courses 2022-06-09T00:00:00Z Therefore, if the cell needs sodium ions, all it has to do is open a passive sodium channel, as the concentration gradient of the sodium ions will drive them to diffuse into the cell. Anatomy and Physiology 2013-06-19T00:00:00Z During active transport, energy is expended to assist material movement across the membrane in a direction against their concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z The flood of sodium ions through the symporter provides the energy that allows glucose to move through the symporter and into the cell, against its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Active transport allows cells to move a specific substance against its concentration gradient through a membrane protein, requiring energy in the form of ATP. Anatomy and Physiology 2013-06-19T00:00:00Z Figure 5.10 Some substances are able to move down their concentration gradient across the plasma membrane with the aid of carrier proteins. Biology for AP Courses 2022-06-09T00:00:00Z Some of these molecules enter and leave cells using facilitated transport, whereby the molecules move down a concentration gradient through specific protein channels in the membrane. Anatomy and Physiology 2013-06-19T00:00:00Z Because the concentration of Na+ is higher outside the cell than inside the cell by a factor of 10, ions will rush into the cell that are driven largely by the concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Water absorption is driven by the concentration gradient of the water: The concentration of water is higher in chyme than it is in epithelial cells. Anatomy and Physiology 2013-06-19T00:00:00Z Thus, water moves down its concentration gradient from the chyme into cells. Anatomy and Physiology 2013-06-19T00:00:00Z This diffusion of water through the membrane—osmosis—will continue until the concentration gradient of water goes to zero or until the hydrostatic pressure of the water balances the osmotic pressure. Biology for AP Courses 2022-06-09T00:00:00Z It also functions to maintain a concentration gradient with higher glucose levels in the blood than in the tissues. Anatomy and Physiology 2013-06-19T00:00:00Z A concentration gradient acts on K+, as well. Anatomy and Physiology 2013-06-19T00:00:00Z Simple diffusion moves a substance from a higher to a lower concentration down its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Facilitated diffusion is similar to diffusion in that it moves a substance down its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z In this situation, water will follow its concentration gradient and enter the cell. Biology for AP Courses 2022-06-09T00:00:00Z The cotransporter moves glucose into the cell against its concentration gradient as Na+ moves down the electrochemical gradient created by the basal membranes Na+/K+ ATPases. Anatomy and Physiology 2013-06-19T00:00:00Z Eventually the sugar will diffuse throughout the tea until no concentration gradient remains. Anatomy and Physiology 2013-06-19T00:00:00Z A Na+/K+/2Cl– symporter in the apical membrane passively allows these ions to enter the cell cytoplasm from the lumen of the loop down a concentration gradient created by the pump. Anatomy and Physiology 2013-06-19T00:00:00Z Solutes also move across the capillary wall according to their concentration gradient, but overall, the concentrations should be similar and not have a significant impact on osmosis. Anatomy and Physiology 2013-06-19T00:00:00Z ATP is required to move sodium ions against their concentration gradient outside the cell. Biology for AP Courses 2022-06-09T00:00:00Z Discuss the mechanism cells employ to create a concentration gradient to ensure continual uptake of glucose from the bloodstream. Anatomy and Physiology 2013-06-19T00:00:00Z Whenever a substance exists in greater concentration on one side of a semipermeable membrane, such as the cell membranes, any substance that can move down its concentration gradient across the membrane will do so. Anatomy and Physiology 2013-06-19T00:00:00Z Sodium is actively pumped out of the PCT into the interstitial spaces between cells and diffuses down its concentration gradient into the peritubular capillary. Anatomy and Physiology 2013-06-19T00:00:00Z Sodium moves down its electrochemical and concentration gradient into the cell and takes glucose with it. Anatomy and Physiology 2013-06-19T00:00:00Z In solutions containing more than one substance, each type of molecule diffuses according to its own concentration gradient, independent of the diffusion of other substances. Biology for AP Courses 2022-06-09T00:00:00Z These are found between cells of the ascending loop, where they allow certain solutes to move according to their concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Powered by ATP, the pump moves sodium and potassium ions in opposite directions, each against its concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z Passive transport of a molecule or ion depends on its ability to pass easily through the membrane, as well as the existence of a high to low concentration gradient. Anatomy and Physiology 2013-06-19T00:00:00Z |
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