Lesson 8 Societal Applications
Uses of Cell Membranes
Scientists have modelled many technologies and treatments after the cell membrane.
The cell membrane is an amazing example of a semipermeable or selectively permeable membrane. This means the cell membrane only allows some particles to move through it to the other side. Knowledge of how this works has been very helpful in a variety
of ways.
A8.11 The kidneys
Normally, healthy kidneys would remove wastes from the blood and send them to be eliminated in the urine. When the kidneys fail, doctors need to either do a kidney transplant or have the patient undergo dialysis to remove the wastes. Often
patients have to wait a long time for a kidney to be available for transplantation, so dialysis allows them to continue with their lives as best they can while they wait.
The purpose of dialysis is to remove the wastes so the body does not poison itself. A tube is inserted into the abdominal cavity (the space surrounding the intestines) and is used to pump a sterile fluid called dialysate into the cavity.
The dialysate has concentrations of molecules similar to that of other body fluids but does not contain any waste products. This means there is a higher concentration of the waste products in the blood than in the dialysate. The wastes
move down the concentration gradient through diffusion and into the dialysate. As the concentration of wastes in the dialysate gets too high, it is removed and replaced with clean dialysate. This continues until all the wastes are
removed.
In this case, the patient is able to continue with most activities when this type of dialysis is occurring. There is another type of dialysis called hemodialysis (“hemo” for hemoglobin found in blood), which requires hospitalization to be performed. Hemodialysis still uses the diffusion and semipermeable membranes, but the blood is removed from the body to clean it.
In this case, the patient is able to continue with most activities when this type of dialysis is occurring. There is another type of dialysis called hemodialysis (“hemo” for hemoglobin found in blood), which requires hospitalization to be performed. Hemodialysis still uses the diffusion and semipermeable membranes, but the blood is removed from the body to clean it.
© Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436.
A8.12 Peritoneal Dialysis
A8.12 Peritoneal Dialysis
Digging Deeper?
©Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436.
A8.13 Hemodialysis
A8.13 Hemodialysis
Hemodialysis is another type of dialysis that patents with kidney failure can undergo. Go to the following link for more information on hemodialysis. https://www.nhs.uk/conditions/dialysis/what-happens/
Learn More
A8.14 Map of Antarctica
Reverse Osmosis is a process that is often used to remove salt (desalination) and other impurities from sea water. This is done in locations around the world where fresh water is hard to come by. An example of a location such as this
would be the research facilities in Antarctica. All the water except the ocean water is frozen in Antarctica, so the only option is to drink the ocean water. If we did not remove the salts and impurities from this water, we would become
very sick, as the
concentrationof salt in ocean or sea water is very high. Using what you know about osmosis and diffusion, why do you think this would be?
To start this process, the water is pumped through a coarse filter to remove any large materials that may be in it, such as plant or animal remains and rocks. The water is then pumped through smaller and smaller filters to remove smaller and smaller impurities. These membranes are semipermeable membranes as they only allow particles through that are small enough. Eventually, the water will have all the salt and impurities removed.
To start this process, the water is pumped through a coarse filter to remove any large materials that may be in it, such as plant or animal remains and rocks. The water is then pumped through smaller and smaller filters to remove smaller and smaller impurities. These membranes are semipermeable membranes as they only allow particles through that are small enough. Eventually, the water will have all the salt and impurities removed.
This process is called reverse osmosis because the solution left behind each membrane has a higher concentration of impurities than the solution after it. This means the water is moving from a solution of high concentration to
a solution of low concentration; the water is moving against the concentration gradient. Because of this, reverse osmosis requires the water to be pumped, and it uses energy. This causes the process to be expensive, so it is
only used when there are few other options.
A8.15 Osmosis vs Reverse Osmosis
Did You Know?
A8.16 Reverse osmosis system
You can purchase home reverse osmosis systems. Just search “reverse osmosis,” and you will get a list of locations you can buy one and the price.
A8.17 HIV attacking a cell
Both HIV (human immunodeficiency virus) and cancer are hard to treat as they affect most cells in the body, so medications often target healthy cells as well as affected ones. Scientists are constantly trying to find ways to target only
the affected cells. If we could only kill the affected cells, we could cure or at least stall the disease rather than constantly fighting it.
One area of research is around cell communication. The proteins found moving around in the cell membrane are a very important part to cell communication. Specifically, receptor proteins recognize molecules that are needed in the cell and bind with them to bring them in through endocytosis. HIV uses this mechanism to enter a healthy cell. It mimics a molecule that is needed by the cell so that the receptor proteins bind with HIV to bring it into the cell. Scientists feel if they can better understand how these receptor proteins work, they can block HIV out from using them to enter the cell.
Cancer research has also moved in this direction, as these proteins in the membrane are also used for cell recognition. If scientists understood what protein or what part of a protein signalled a cancerous cell, they could create a treatment that targeted those cells rather than all cells in the body.
One area of research is around cell communication. The proteins found moving around in the cell membrane are a very important part to cell communication. Specifically, receptor proteins recognize molecules that are needed in the cell and bind with them to bring them in through endocytosis. HIV uses this mechanism to enter a healthy cell. It mimics a molecule that is needed by the cell so that the receptor proteins bind with HIV to bring it into the cell. Scientists feel if they can better understand how these receptor proteins work, they can block HIV out from using them to enter the cell.
Cancer research has also moved in this direction, as these proteins in the membrane are also used for cell recognition. If scientists understood what protein or what part of a protein signalled a cancerous cell, they could create a treatment that targeted those cells rather than all cells in the body.
Read This
Please read pages 284 to 288 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the different functions of cell membranes and cell transport and how those functions use diffusion, osmosis,
and semipermeable membranes. Remember, if you have any questions or you do not understand something, ask your teacher!
Practice Questions
Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses
(where necessary) to study from.
- Explain how the process of reverse osmosis works.
Water with impurities is pushed through a semi-permeable membrane that does not allow the impurities to go through. Since the water is moving from a high concentration of impurities to a low concentration, the water is moving against the
concentration gradient, making it reverse osmosis rather than osmosis.
- How does peritoneal dialysis use membrane technology?
Peritoneal dialysis uses the semi-permeable membranes in the body. These semi-permeable membranes allow the waste products to move from the blood vessels and organs into the dialysate that is sitting in the abdominal cavity.