Physioex 8 Exercise 1

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Simple Diffusion
Activity 1: Simulating Simple diffusion

1.What is the molecular weight of Na+? 22.9
2. What is the molecular weight of Cl-? 35.45
3. Which MWCO dialysis membranes allowed both of these ions through? 50, 100, and 200 4. Which materials diffused from the left beaker to the right beaker? Urea, NaCl and glucose diffused 5. Which did not? Why? Albumin, because the molecular weight exceeded the highest MWCO membrane, thus being to large to pass through

Activity 2: Simulating Dialysis

1. What happens to the urea concentration in the left beaker (the patient)? It is reduced to 50% travels to the right beaker and reaches equilibrium at 17 minutes 2. Why does this occur? Because the more concentrated it became it causes the molecules to move down

Facilitated Diffusion
Activity 3: Facilitated Diffusion
1. At a given glucose concentration, how does the amount of time it takes to reach equilibrium change with the number of carriers used to “build” the membranes? The higher number of carriers the quicker it reaches equilibrium 2. Does the diffusion rate of Na+/Cl- change with the number of receptors? No 3. What is the mechanism of the Na+/Cl- transport? Plasma vessels Look at #2 above; it’s simple diffusion because there is no change in diffusion rate with the number of receptors. The glucose that’s actively transported not the salt. If it did the amount of NaCl transported would increase with the number of receptors. The receptors are specific for glucose. -2.5pts

4. If you put the same amount of glucose in the right beaker as in the left, would you be able to observe any diffusion? No 5. Does being unable to observe diffusion necessarily mean that diffusion is not taking place? No

Activity 4: Osmosis

1. Did you observe any pressure changes during the experiment? If so, in which beaker(s), and with which membranes? Yes in the Left beaker...
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