BMS100 Plus Hours Assignment - "Cell Transport Mechanisms & Permeability" on PhysioEx
    Instructions
  • Go to the Biology Computer Lab, EBS 215. See lab hours.
  • Start the PhysioEx software and make the following selections:
    Main Menu > Cell Transport Mechanisms & Permeability

  • Go to the Experiment menu and select Simple Diffusion. (If this Experiment will not open, select another then come back to this one.)
    1. This module will allow you to understand how dialysis machines ("artificial kidneys") can be used to cleanse blood when a person's kidneys are nonfunctional. During the process, blood is diverted from an artery of the patient's body, passed through a tubular dialysis membrane within a dialyser chamber, then returned to a vein of the patient's body. While in the dialyser, the blood contained within the tubular dialysis membrane is surrounded by a pure, fresh fluid, into which waste products can diffuse. Valuable substances in blood, such as protein, cannot pass through the dialysis membrane. Diagrams:
      • Dialysis Machine - note the dialyzer chamber, which contains the dialysis membrane.
      • The Dialysis Membrane
        • is inside the dialyser and surrounded by a fresh solution
        • has the patient's blood passing through it
        • is permeable to waste products
        • is impermeable to proteins and other valuable molecules
    2. Now view the apparatus shown on the PhysioEx software. Note the two clear chambers near the top center. For this experiment, the chamber on the left represents blood that is passing through the dialyser. The chamber on the right represents the fluid that surrounds the blood inside the dialyser, which is disposed at the end of the procedure. Remember that a dialysis membrane separates the two fluids from each other.
    3. Use the + button on the left to raise the concentrations of Na+/Cl-, urea, albumin, and glucose to the maximum allowed (20 mM each). Click Dispense to put the fluid into the chamber on the left.
      • Albumin is the predominant protein that is normally present in blood. Albumin and glucose (blood sugar) are valuable substances that need to be conserved within blood.
      • Urea is a waste product that needs to be removed from the blood during the dialysis process.
    4. Use the + button on the right to raise the concentration of Na+/Cl- to the maximum allowed (20 mM). Click Dispense to put the fluid into the chamber on the right.
    5. Use the mouse to put the 100 MWCO Dialysis Membrane in the slot between the two chambers. A "100 MWCO" membrane has pores through which only particles with molecular weight 100 or less can pass.
    6. Click Start and watch what happens to the concentrations of the various substances.
      Question #1: Which substance did pass through the dialysis membrane for eventual disposal under these conditions?
      Question #2: Which substances did not pass through the dialysis membrane, and will therefore remain in the patient's blood?

  • Go to the Experiment menu and select Facilitated Diffusion. (If this Experiment will not open, select another then come back to this one.)
    1. Go to the Membrane Builder, use the + button to increase the number of Glucose Carriers to 1000, and click Build Membrane. Drag the membrane to the holder between to two large containers.
    2. Below the left side container, use the + to raise the glucose concentration to 20 mM, and click Dispense to fill the left container.
    3. Below the right side container, use the + to raise the Na+/Cl+ concentration to 20 mM, and click Dispense to fill the right container.
    4. Click Start and wait for 60 seconds.
      Question #3: After 60 seconds, what is the glucose concentration in the left container? In the right container?
      Question #4: Did the glucose concentrations equalize between the two sides, or did one side end up with a greater concentration?
    5. Drag the membrane back to the Membrane Builder and Flush both containers.
    6. Go to the Membrane Builder, use the - button to decrease the number of Glucose Carriers to 0, click Build Membrane, and drag the membrane back to the holder.
    7. Refill the left and right containers as directed above.
    8. Click Start and wait for 20 seconds.
      Question #5: After 20 seconds, what is the glucose concentration in the left container? In the right container? Do carriers appear to be necessary for glucose to pass through the membrane?

  • Go to the Experiment menu and select Osmosis. (If this Experiment will not open, select another then come back to this one.)
    1. In this experiment, we will imagine that the container to the left represents a blood vessel in the cardiovascular system, and the container to the right contains the fluid located outside the blood vessel. We will also assume that it is necessary to maintain pressure in the blood vessel at all times.
    2. Go to the right, find the 20 MWCO membrane, and drag it to the holder between the two large containers.
    3. Use the + button on the left to raise the Albumin concentration to 20 mM. Albumin is the main type of protein that is present in blood. In this experiment, it represents a solute (substance dissolved in fluid). Click Dispense to fill the left container.
    4. Click the Deionized Water button below the right side container and click Dispense to fill the right side container with water.
    5. Click the Start button and watch the Pressure meters above each of the containers. These meters are measuring osmotic pressure and the units of measurement are mmHg. This pressure contributes to the total pressure in the blood vessels of the cardiovascular system.
      Question #6: After 60 seconds, what is the osmotic pressure in the left side container? In the right side container?
      Question #7: Did the pressure rise on the side that had more solute or the side that had more water?
    6. Cardiovascular shock, and certain types of liver disease, result in lowered albumin concentration in blood and possibly elevated protein content in the fluid outside the vessels.
    7. Repeat the experiment as if some protein passed from the blood (left side) to the fluid outside the vessel (right side). Set the left side albumin concentration to 15 mM and the right side albumin concentration to 5 mM.
      Question #8: After 60 seconds, what is the osmotic pressure in the left side container? In the right side container?
      Question #9: In this experiment, what is the effect of lowered concentration of albumin (protein) in the blood?

  • Go to the Experiment menu and select Active Transport. (If this Experiment will not open, select another then come back to this one.)
    1. Note the two clear chambers near the top center. For this experiment, the chamber on the left represents fluid inside a cell such as a brain cell or a heart muscle cell. The chamber on the right represents the fluid outside the cell.
    2. Use the + buttons on the left to raise the concentrations of Na+/Cl- and K+/Cl- to the maximum allowed (20 mM each). Click Dispense to put the fluid into the chamber on the left.
    3. Use the + buttons on the right to raise the concentrations of Na+/Cl- and K+/Cl- to the maximum allowed (20 mM each). Click Dispense to put the fluid into the chamber on the right.
    4. Use the + button in the ATP bar to raise the concentration of ATP to the maximum allowed (20 mM). Click Dispense ATP to provide the cell with ATP.
    5. Click the Build Membrane button to create a membrane using the default values, then drag the membrane to the slot between the two clear compartments.
    6. Click the Start button and watch what happens to the Na+ and K+ concentrations inside the cell.
      Question #10: What happens to each of the following concentrations during the Active Transport Experiment?
      1. Na+ concentration inside cell: increase OR decrease?
      2. Na+ concentration outside cell: increase OR decrease?
      3. K+ concentration inside cell: increase OR decrease?
      4. K+ concentration outside cell: increase OR decrease?

  • Your answers may be submitted via e mail or on paper. If using e mail:
    • Go into your e mail software and create a new message.
    • In the subject line, put one of the following:
      • Mbms100memb if you are enrolled in the Monday lab
      • Wbms100memb if you are enrolled in the Wednesday lab
      • THbms100memb if you are enrolled in the Thursday lab
    • Copy the following list of questions and paste it into the body of the e mail message.
    • Type in your answers to the questions.
    • Send the e mail to connell@sbcc.edu and send a Cc to yourself as a "receipt." 
    Your full name and lab section:
1. Which substance did pass through the dialysis membrane for eventual disposal under these conditions?
2. Which substances did not pass through the dialysis membrane, and will therefore remain in the patient's blood?
3. After 60 seconds, what is the glucose concentration in the left container?
	In the right container?
4. Did the glucose concentrations equalize between the two sides, or did one side end up with a greater concentration?
5. After 20 seconds, what is the glucose concentration in the left container?
	In the right container?
	Do carriers appear to be necessary for glucose to pass through the membrane?
6. After 60 seconds, what is the osmotic pressure in the left side container?
	In the right side container?
7. Did the pressure rise on the side that had more solute or the side that had more water?
8. After 60 seconds, what is the osmotic pressure in the left side container?
	In the right side container?
9.  In this experiment, what is the effect of lowered concentration of albumin (protein) in the blood?
10. What happens to each of the following concentrations during the Active Transport Experiment?
	a. Na+ concentration inside cell: increase OR decrease?
	b. Na+ concentration outside cell: increase OR decrease?
	c. K+ concentration inside cell: increase OR decrease?
	d. K+ concentration outside cell: increase OR decrease?
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    Fall 2011