List the factors that influence diffusion rates across the call membrane?
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Given that a certain type of molecule is small enough to permeate through the cell membrane, the most important factor influencing the rate of diffusion is the concentration gradient.  This is simply the difference in concentration levels of the substance between the outside and the inside of the cell.  The larger the difference in concentrations, the greater the rate of diffusion.
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The distribution of ions across a cell membrane produces a concentration gradient that can be used by the cell to do various kinds of work (i.e. power non-spontaneous reactions).  \n\nFor example, in mitochondria and certain aerobic bacteria, the gradient of H+ ions powers ATP synthase, and allows it to make ATP (an extremely important energy storage molecule).  \n\nIn other cells, the concentration gradients of ions can be used to facilitate active transport across the membrane by coupling an ion moving along it's concentration gradient with another molecule moving against it.\n\nIn neurons, the difference in the concentrations of ions inside and outside the cell creates a membrane polarity that allows the action potential (i.e. the nerve firing) to occur.  When the nerve is activated by a neurotransmitter or a direct external stimulus, sodium channels open, allowing Na+ to rush into the cell, making it positive relative to the external environment.  This change in polarity moves along the cell, and causes the cell to release specific neurotransmitters at the other end.\n\nIf the ions were distributed equally, none of the processes I just mentioned would work!
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In the absense of additional information or context the basis for this question rests in the size of the molecule. The smaller molecule will have a greater rate of diffusion than the larger molecule.  In general size of molecules is directly proportional to their molecular weight. When all molecules are the same molecular weight you will need to consider which ones are smaller based on the attractive forces between them. \n\na)  CO and N2 - N2 has a triple bond (the Ns are held closely to each other therefore small) and is very stable and I would bet that it will diffuse faster than CO since its actual size is smaller and because it is stable it is less likely to react with any medium through which it is diffusing.\nb) No2 and SO2 - this is likely to be based on size with the larger SO2 diffusing more slowly.\n\nHope this helps.
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Basically the semi-permeable membranes and capillary beds carry out osmosis. Osmosis is the passive diffusion of water molecules from a higher water potential to a lower water potential. Water moves from an area with higher concentration of water to an area with less water until the concentration of water in both areas become equal. Semi-permeable membranes and capillaries have thin walls that allow the passage of water. Thus water can move according to its concentration across the membranes.
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341m/s but it changes according to the weather conditions in humid climate it is faster as compared to dry.and yeah sound does not travel through vacuum\nspeed of sound in solids > liquids > gases
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some cells to take in more. Cell permiablility.\n\nhttp://www.answers.com/topic/cell-permeability
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Increased surface area means increase diffusion capability.
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Osmosis and diffusion are both passive (do not require energy). They both involove the random movement of molecules from a region of high concentration to a region of low. \nWhen someone sprays perfume into the air, the perfume molecules diffuse around their enviroment, thats why you smell it at the other side of the room after a few seconds.\n\nThe differences are that osmosis is the movement of Water molecules from a high concentration to a low concentration through a semi permeable membrane.
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The rate of diffusion in a material is determined by \nthe density of the  material\nporosity present in the material\nthickness of the material\nvelocity at which the diffusant traveling towards the material.\n\nIf the diffusant is liquid, the viscosity of the liquid.
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Solutes that are too polar or highly charged to diffuse through the lipid bilayer and are too big to diffuse through membrane channels can cross the plasma membrane by facilated difussion.In this process, a solute binds to a specific transporter on one side of the membrane and is released on the other side after the transporter undergoes a changhe in shape.\n\nLike diffusion, facilitated diffusion is a passive process.The net result of facilitated diffusion is movement down a concentration gradient.The solute binds more often to the transporter on the side of the membrane with a higher concentration of solute.Once the concentration is the same on the both sides of the membrane,solute molecules bind to the transporter on the cystolic side and move out the extracellular side and move into the cytosol.The rate of facilitated diffusion(how quickly it occurs) is determined by the stepness of the concentration gradient across the membrane.\n\nThe number of transporters available in a plasma membrane places an upper limit,called the transport maximum,on the rate at which facilitated diffusion can occur.Once all the transporters are occupied, the transport maximum is reached, and further increase in the concentration gradient does not increase the rate of facilitated diffusion.Thus,much like a completely saturated sponge can absorb no more water,the process of facilitated diffusion exhibits saturation.\n\nHope this helps you.Please check my spelling too.I may misspelled some words.So many too typed.No time to check it.\n(^^o)/
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Movement of substances across the cell membrane is the function of the 3 types of diffusion.\n\n\nThe generalized cell functions include movement of substances across the cell membrane, cell division to make new cells, and protein synthesis. \n\n\nMovement of substances across the cell membrane \nThe survival of the cell depends on maintaining the difference between extracellular and intracellular material. Mechanisms of movement across the cell membrane include simple diffusion, osmosis, filtration, active transport, endocytosis, and exocytosis. \n\nSimple diffusion is the movement of particles (solutes) from a region of higher solute concentration to a region of lower solute concentration. Osmosis is the diffusion of solvent or water molecules through a selectively permeable membrane. Filtration utilizes pressure to push substances through a membrane. Active transport moves substances against a concentration gradient from a region of lower concentration to a region of higher concentration. It requires a carrier molecule and uses energy. Endocytosis refers to the formation of vesicles to transfer particles and droplets from outside to inside the cell. Secretory vesicles are moved from the inside to the outside of the cell by exocytosis.
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look at this website\n\nhttp://www.liv.ac.uk/~petesmif/teaching/1bds_mb/notes/pores/text.htm
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A few things I can think of right off my head, without reviewing physiology.  Very basic info here, for more details, you can find it in any good physiology textbook.\n\nSmoke in cigarrettes decreases the capacity for hemoglobin to carry O2, and thus decreases the efficiency for O2 diffusion.\n\nCO2 decreases the surfactant in the lungs, making them less efficient in CO2/O2 exchange.\n\nCO2 also damages cells lining the blood vessels (capillaries) that are important in the diffusion process.
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1. lipoprotein sandwich\n2. receptor sites\n3. porus\n4. allows for diffusion\n5. allows for active and passive transport\n6. includes chlosterol
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If you're speaking of passive diffusion across the membrane, heat will increase the fluidity of the membrane making it more permeable.\n\nWith facilitated diffusion, involving a tranmembrane enzyme, the permeability increases to a point, and then decreases as the enzymatic structure is degraded
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Difusion is the movement of particles from an area of high concentration to an area of low concentration, until they are apread out evenly.\n\nExamples for diffusion: \nThe alveoli are well adapted for diffusion of gases, \nthey have a large surface area\nthey are moist, so gases can dissolve\nthey have thin walls\nand a good blood supply.\n\nThe small intestine is specialised for absorption. \nIt has: \nA thin lining\na good blood supply\na very large surface area.\n\nOsmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane.\n\nA partially permeable membrane allows water molecules to pass through, but not solute molecules.\n\nWhen a plant cells are full of water they are turgid.\nThis rigidity or turgour gives the plant support\nCells are able to absorb some substances against a concentration gradient.\n\nActive transport needs energy from respiration. \n\nActive transport....\nNot all sustances pass into cells by diffusion or osmosis. Some substances are absorbed against a concentration gradient. But to do this energy is needed and it comes from respiration. This process is called ACTIVE TRANSPORT.\nExample of active transport are:\nThe uptake of ions by root hair cells from the soil, where they are in very dilute solution;\nthe uptake of sugar molecules into the small intestine;\nthe re-absorbtion of useful ions in the nephrons of the kidneys.
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this would be easier to google if you spelled it correctly, i imagine.\n\nlets assume you arent asking: what 'makes' it selectively permeable, but what 'causes' selective permeability.\n\nthe easy answer would be the code of the construction of the membrane (what makes me a boy--my code--genetics, what makes my air filter let air pass but not dog hair--the code--the engineering diagram) which usually defines permeability in one of three ways: rate, shape or size.\nrate: how fast can water go through my reverse osmosis (LOL) filter. 50 gallons a day. but ALL h20 goes through.\nshape: what can get through the cell membrane, anything that matches the shape of the protein that carries it across.\nsize: large rocks get caught on the screen, but small rocks go through.\n\nmaybe you can define a little...clarify seletively permeable or selective permeability, human biology or water filtration? \n\neither way, this link might help (or might be 5 years behind you! sorry, dont know!)