1. What happens to RBC placed in hypertonic solutiona? mink!-see p.4) one contai

Question

1. What happens to RBC placed in hypertonic solutiona? mink!-see p.4) one containing more Na Cr than 3 Osm) WHY? m. What is crenation? (4; B) n. Does osmosis occur during crenation? After crenation? What is net flow after? (Thinkt) o. Why did hemolysis oceur more rapidly in some tubes than in other tubes? c. Questions related to: MEMBRANE PERMEABILITY 1. Explain why 0.3 0sm urea (which is isotonic) caused hemolysis of RBC which are 0.3 0sm inside. Give exact mechaniem? Be su you know this. c) 2. What happens to RBC placed in: (xplain why?) s,o 3 M ethylene glycol 3 N glycerol 3 M glucose a. Why was the result not the same for each? SC. Give mechanism. mirkn b. Why was time to hemolysis for ethylene giycol, thiourea and gi different from urea? (p.3:C) c. This experiment demonstrated the influence of on menbrane permeability. (Think!) d, what should happen if RBC are placed in a 0.3 M urea plus 0 .15 M Naci solution?Explain sxastly why this happens. 3. Convert the following to osmolarity. (Taink) 2 M Cacl2 .2 M CasO4 .2 M Nac) .2 M urea .2 M glucose 4. Label the above as isotonie, hypotonie, or hypertonie. mk) 5. Is an iso-osmolar solution also isotonic? Explain. 6. What controls rate of diffusion of aubatances through cell membranes.mhiakt) 7· Name five ways the body uses diffusion or osmosis. alkn .2 M thiourea 205 Lab4 page 9

Explanation / Answer

1. The osmolarity of red blood cells in the blood is 0.3 Osm. An isotonic solution of urea (0.3 Osm) causes hemolysis of RBCs because it is iso-osmolar in nature. An iso-osmolar solution contains solute molecules that can enter into the cell membrane of neighbouring cells. SInce urea is iso-osmolar in nature, the urea molecules enter the RBCs, making the solution around the RBCs (i.e. the urea solution) hypotonic and leading to the hemolysis of RBCs.

2. All the given solutions lead to hemolysis of RBCs but at different rates.

a) The results for each solution varied because the rate of hemolysis is inversely propotional to the size of the solute of the solutions. This means that smaller the solute size, the higher will be the rate of hemolysis.This is because the smaller size of the solute will increase the ease of movement through the cell membrane for the solute.

b) As explained in a), due to the difference in solute sizes for the given solutions, the rate of hemolysis varied. The rate of hemolysis is arranged as follows -

urea < ethylene glycol < thiourea < glycerol < glucose

c) This experiment demonstrates the influence of solute size on membrane permeability.

d) Since the osmolarity of 0.3 Osm urea solution and 0.15 Osm NaCl solution, the osmolarity would not be affected. However, since the solution already is iso-osmolar in nature, hemolysis of RBCs will occur.

3. Osmolarity = number of particles/ ions x molarity

So,

0.2 M NaCl = 0.2 x 2 = 0.4 Osm NaCl

0.2 M CaCl2 = 0.2 x 3 = 0.6 Osm CaCl2

0.2 M CaSO4 = 0.2 x 2 = 0.4 Osm CaSO4

5. The example of urea as explained in Q1 answers this.

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