Diffusion and Osmosis (via Khan Academy).

Osmosis Computer Simulation: "This is a shot from a three dimensional computer simulation of the process of osmosis. The blue mesh is impermeable to the larger balls, whereas all of the balls are (in the animated version) bouncing about according to the rules of physical simulation of the kinetics of an ideal gas."

Osmosis Computer Simulation: “This is a shot from a three dimensional computer simulation of the process of osmosis. The blue mesh is impermeable to the larger balls, whereas all of the balls are (in the animated version) bouncing about according to the rules of physical simulation of the kinetics of an ideal gas.”–Via Wikipedia. 

“There is more evidence to prove that saltness [of the sea] is due to the admixture of some substance, besides that which we have adduced. Make a vessel of wax and put it in the sea, fastening its mouth in such a way as to prevent any water getting in. Then the water that percolates through the wax sides of the vessel is sweet, the earthy stuff, the admixture of which makes the water salt, being separated off as it were by a filter.”

[This is an example of Aristotle giving proof by experiment, in this case, of desalination by osmosis.]

Even 2,000 years after Aristotle’s rough experiment, scientists, students, and teachers still have something to say about this phenomenon; which “plays a role in the blood circulation, keeping just the right balance between the water content of the blood and the surrounding tissues. Osmosis drives fluid flow in the kidneys, preventing waste products from accumulating to dangerous levels. Osmosis is also the driving force behind plant cell expansion, playing a role in flower and fruit growth.” (Via Scientific American, May 1, 2013).

The following video from Khan Academy illustrates what Aristotle observed. It also provided explanations through the use of experimental models:

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45 thoughts on “Diffusion and Osmosis (via Khan Academy).

  1. This is amazing! I had no idea that osmosis was so important in our bodies. Without osmosis our blood wouldn’t circulate the same way and there wouldn’t be balance between the water in our blood and the surrounding tissue. Osmosis is vital for us even though we don’t notice. It isn’t just important for humans, it also helps in plant cell expansion and the making of flowers and fruits.

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  2. That video was really helpful. Diffusion and osmosis are very important for living things because they help maintain balance in our cells of nutrients and water. I found a website with animations that help explain these terms and the process they go through before reaching equilibrium. In addition to the videos, I am looking forward to the potato experiment we will do in the classroom in which we will observe how osmosis works.
    http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/kidneys3.cfm?coSiteNavigation_allTopic=1

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  3. Diffusion is one of the most important process in life and by many people it is taken for granted. Diffusion is the legs of molecules. It helps it move, creating reactions needed for life, it one of the most important methods of transportation for molecules that don not have legs nor any adaptation for transportation like oxygen. It is present in everyday life, diffusion helps your body get oxygen to the muscle, and other parts. Diffusion is essential to all living organisms because it helps water and other nutrients enter and leave the cell.
    This first link is an animated explanation of all the processes having to do with diffusion and the movement of molecules
    http://www.phschool.com/science/biology_place/labbench/lab1/intro.html
    This second link explains the diffusion in detail. The tittle of the site called my atention “Science Is Art” which one topic in another blog
    http://www.scienceisart.com/A_Diffus/DiffusMain_1.html

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    • I agree. Diffusion is what actually allows molecules to move, but keep in mind that this process in the result of the kinetic energy of subatomic particles. So diffusion is much a physics phenomenon as it is biological.

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  4. After talking about osmosis and diffusion in class and after seeing this post, I got interested in knowing more about these things. So I searched “osmosis” on Google and found this article (Link below). It talks about how, apparently, many chemists and biologists have misconceptions on what osmosis truly is. I am not a biologist or a chemist so I don’t know if all these things are true, so I would like to know if these things are accurate and if they are why haven’t chemists or biologists realized they are wrong?

    Link: http://phys.org/news/2013-04-osmosis-wrong.html

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  5. Osmosis is one of the most important processes in all living things because it influences the distribution of nutrients and the release of metabolic waste products. All living cells are enclosed by a semipermeable membrane called the cell membrane, which regulates the flow of liquids into and out of the cell. This membrane forms a barrier between the cell and its environment. But, not all substances can pass through the membrane with equal facility. Without this selectivity, the substances necessary to the life of the cell would diffuse uniformly into the cell’s surroundings, and toxic materials from the surroundings would enter the cell.

    Here is a picture of the process:

    Animation of the process of osmosis:
    http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

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  6. Diffusion is an amazing topic, especially when talking about osmosis that happens through a membrane! The process is so simple and so complex at the same time. As osmosis helps in movement it also helps in homeostasis keeping the cells in optimum shape for movement. It is incredible that this is taking place right now in every living organism in the world. Many people don’t know this but without diffusion neither the cell nor the human body will be as effective as it currently is.

    This link shows the simplicity yet complexity of the process http://www.biologycorner.com/bio1/notes_diffusion.html

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    • It is very important to understand diffusion and osmosis as a cross-disciplinary topic. Thermodynamics–which basically studies the kinetic (movement) energy of particles–is fundamental for this phenomenon to be properly understood. And the link you shared does a very good job in pointing that out.

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  7. After watching the video I thought about the importance of osmosis and diffusion and how can it be related to our daily lifes, I researched and found a super cool video that pretty much explains osmosis and diffusion but also gives examples and experiments we can do. Its awsome you should see it.

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  8. I had no idea osmosis was this important for our daily lifes. Before we looked deeper into the subject and before a read the blog I thought that osmosis only helped the cell live and therefore it helped us but I didn’t know in which ways. A small process can balance the water that is in your blood or prevent waste products from accumulating dangerously. Osmosis not only helps humans but it also helps plants with flower and fruit growth. Osmosis plays a very important role in the life of a human and a cell. This is an example of how the small things in life can make a huge difference.

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  9. What difference would it make in the diffusion of the particles if the solvent, instead of being water, would be some other kind of liquid like ethanol?

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    • The osmosis of ethanol is possible thanks to a process known as Countercurrent reverse osmosis (CCRO). Fuels based in ethanol benefit from this process. Its design “helps solve a major problem in enriching ethanol by reverse osmosis: the high osmotic pressure of concentrated ethanol solutions.”

      The following excerpt was taken from a paper published by the ACS (American Chemstry Association): “[T]he effective osmotic pressure gradient across a membrane is reduced by supplying the permeate side of the membrane with a solution more concentrated in ethanol than the permeate but less concentrated than the feed. This causes ethanol to back-diffuse from the recirculation solution into the membrane. The concentration increase inside the membrane lowers the concentration difference (and thus the osmotic pressure difference) between the feed-solution and membrane phases. Membranes with open porous sublayers are preferred for use in CCRO because they allow ethanol to diffuse relatively unhindered through the sublayer and accumulate inside the membrane. With a new thin-film-composite membrane, designated 3N8, it has been shown that CCRO is about seven-fold more energy-efficient.”

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  10. I was searching to understand diffusion and osmosis in our everyday tasks. When we breathe, oxygen is taken to the lungs where it is then diffused into the bloodstream. When we go to the pool for a long period of time, our fingers start to prune. This is because the skin absorbs the water (diffusion). Also, when you soak a sponge in a pail of water, the sponge expands because of diffusion, since the sponge absorbs the water. When cooking rice, the rice absorbs the water from the pot because of diffusion. It is interesting to see how our daily functions depend greatly on diffusion and osmosis.

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  11. This video really helped me to understand osmosis. It made the difference between a hypotonic and a hypertonic solution so much easier to understand!!! This video shows us how even microscopic things are vital and irreplaceable for life. Thanks for showing it to us:)

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  12. Before discussing this topic I really didn’t quite understand the importance of particles going from a high concentration to a lower one. But after some research I learned that a seemingly simple process like diffusion is essential for the human body and it can even prevent the drying of eyes. Eyes lack a great number of blood vessels (which carry oxygen that diffuses into the cell). So they must have an extra supply of oxygen. The atmosphere provides the extra oxygen which is consumed by the eye by the diffusion of oxygen through the cornea. Meanwhile if you find yourself in front of a fire with smoke blown to your face, your eyes will dry out. This is because the atmosphere is very dirty and oxygen is at a low concentration.

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  13. I am guilty of “studying by osmosis.” If I concentrate hard enough, all the information inside of the closed book on my desk, the hypertonic solution, will slowly diffuse into my brain, the hypotonic one. With faith, trust, pixy dust, and the power of science, trust me.

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  14. With the help of the Internet, today’s biology class, and this blog post I was able to understand so many things about Osmosis. There are many ways to explain why osmosis is so vital to life.
    Osmosis is the mechanism by which water flows from a solution with low solute concentration to that with a higher one via a semi-permeable membrane. Water moves passively through this membrane in order to achieve equilibrium. The semi-permeable membrane forms a selective barrier between the cell and its environment. This function is extremely important because without this selectivity the substances necessary to the life of the cell would diffuse uniformly.
    Without osmosis water is unable to move in or out of cells. Without water, cells will die and if water doesn’t move out, then the cell could get to saturated and burst. All the biological processes would get ruptured without osmosis.
    I believe osmosis is a prime importance in living organisms since it influences the distribution of nutrients and the release of metabolic waste products.
    Osmosis is also vitally important to a complete understanding of cellular biology.

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  15. Thank you for showing us this video in class! It certainly made it easier to understand diffusion and osmosis, as well as the difference between a hypertonic and hypotonic environment. Recently, I found some links (shown below) that simplified the topic even further for me, helping me focus on what really happens during the different processes that take place in the cell and clarifying any lingering doubts in my mind. I encourage you to check them out in case you still have questions about this topic!

    http://www.diffen.com/difference/Diffusion_vs_Osmosis
    http://www.diffen.com/difference/Active_Transport_vs_Passive_Transport

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  16. Pingback: Last post of Sem. I (2013) of Bio: a Recap | The Hypertextual Lounge

  17. After learning about diffusion and osmosis I finally understood why for example grapes get dry when put in water with salt for a long time. I learned it happens because water from the cells inside the grape move to where their is a lower concentration of water(the water with salt outside of the grape because is mainly salt and not so much water) and leave the cell squeezed out of water making the grape look like a raisin. I found this fact really interesting. The video also helped me understand diffusion better. Before this class and video I was unaware of the importance of concentration gradient, osmosis, and diffusion in our daily lives.

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  18. If we compare osmosis and diffusion with other biological process like photosynthesis, we could say that these to are simpler than photosynthesis. Since the first day they explain to me osmosis and diffusion I have never fully understand their purpose until this year. The cell is completely dependable of this two major processes in order for it to maintain an organism alive because without osmosis, cells cannot gain the water they need to carry out their cell process and without diffusion, gas processes cannot take place in the cell. When you think of the whole picture, our lives depend of just two processes that we may think are very simple but they really are not. Cells do many complex processes at the same time in order to reach all of its many goals and they rarely fail. Even though our bodies are design to be efficient, they make sure to not only be efficient, but to not mistakes because why do something faster if you will have no success or will have to start all over again?

    Here is a link that really gives you all the information needed (and more) to really understand the difference between these to processes.
    http://www.diffen.com/difference/Diffusion_vs_Osmosis

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  19. Diffusion is the movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient. Basically the molecules go from where they are plenty of them to where there are little.

    Osmosis is basically the same thing as diffusion but it deals solely with water. The movement of water molecules from where they are in high concentration to where they are in low concentration.

    Osmosis is very important to all living things because it allows nutrients and waste products to be transported through the walls of the cells.

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  20. At first i was really confused with diffusion and osmosis but after whatching this video it helped me comprehend this so much better. I had no idea osmosis was so important for our daily life. This picture also helped me clear my doubts.

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  21. Osmosis is pivotal for the stabilization of the cell. Stabilization is key for the life of the cell. For example, if water is not distributed equally throughout the cell and its environment, turgor pressure could be going crazy and the cell might explode or shrink depending on the stabilization of the water. If osmosis wouldn’t have existed we would die instantly since we are made mostly of water and if water wouldn’t be distributed equally, as I said, cells would explode or dehydrate. This may sound ridiculous coming from me, but this biology course has made me understand so many things in life, including osmosis.

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    • Water, and everything that has to do with water, have always fascinated me. A proper Biology course has to devote a considerable amount of lecture time to water and it’s interactions with biochemical events on this planet.

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  22. I agree with what you said about water. We should dedicate our time to study it since it is not only a fascinating subject but because it is essential for human life and even our planet earth is made out of 70% of it. As I researched more about water and its abundance in the world I found that water has been detected in interstellar clouds within our galaxy, the Milky Way. Water probably exists in abundance in other galaxies, too, because its components, hydrogen and oxygen, are among the most abundant elements in the universe. Interstellar clouds eventually condense into solar nebulae and solar systems such as ours. Thus, water continues to fascinate me for it is essential for our existence. I can now understand one of many symbolisms that associate water with life. Here is a video of an animation that illustrates how sometimes we do not appreciate water and take it for granted. http://youtu.be/l2eGaiDO_lY

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  23. Diffusion is the process by which molecules spread from areas of high concentration, to areas of low concentration. Osmosis is the diffusion of water (across a membrane). There are three types of solutions and they are isotonic, hypertonic, and hypotonic. When it is isotonic, the amount of solutes and water inside and outside the cell will be equal. If it is hypertonic, then there will be more solutes outside the cell than water and it will shrink. That’s why if you eat a lot of salt, you will get thirsty. Last is hypotonic, that means that there will be more water inside the cell than solutes and it will be filled with water and may burst. In the link, it tells more information about diffusion an osmosis and tips to remember.

    http://www.biologycorner.com/bio1/notes_diffusion.html

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  24. This video was extremely helpful in making me understand how diffusion is the PASSIVE movement of molecules from areas of HIGH concentration to an area of LOW concentration along a DIFFUSION GRADIENT and that Osmosis is the PASSIVE movement of water molecules across a SEMI-PERMEABLE MEMBRANE from an area of HIGH concentration to an area of LOW concentration along an osmotic gradient. Diffusion and Osmosis can be confusing at first, and with this video it was much easier to understand.

    This video is a great overview and summary of Diffusion and Osmosis

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  25. Osmosis is a spectacular phenomenon that helps maintain balance in cells and their surroundings. Because of this, it is extremely important. By studying how osmosis and diffusion work, not only can we gain a better knowledge of what is happening inside our bodies, but also it can be applied to things outside of our cells. Reverse osmosis, for example, is used in the desalination of sea water, a separation process in which the levels of dissolved salt content in water is reduced until it is usable. This process gives more access to potable water, which has been a problem for years.
    http://www.oas.org/usde/publications/Unit/oea59e/ch20.htm

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  26. This video is an excellent way to visualize and understand osmosis and diffusion. These two are very important for life and they play important roles in the respiratory and circulatory systems. Although we use diffusion for the respiratory system, small unicellular and flat organsims depend on diffusion for their oxygen intake more than us because they don’t have lungs. One of these organsims is the tapeworm. Oxygen diffuses into its outer membrane to be broken down and used.

    https://www.boundless.com/biology/textbooks/boundless-biology-textbook/the-respiratory-system-39/systems-of-gas-exchange-219/the-respiratory-system-and-direct-diffusion-830-12073/

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  27. As we studied in class, osmosis is one very important process in all living things. It influences the distribution of nutrients and the release of waste products. During the semester we learned that all cells are enclosed by a semipermeable membrane called the cell membrane, which regulates what goes in and out of the cell and creates a barrier between the cell and it’s environment. Substances that are allowed in and out of the cell are highly selective because without this, necessary substances to the life off the cell would diffuse abnormally into the cell’s surroundings, and hazardous or toxic materials could enter the cell.

    https://www.youtube.com/watch?v=IaZ8MtF3C6M : “A Solute and a Solvent Love Story”

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