Posted: December 2nd, 2022

Physiology Problem Solving Homework

Physiology Problem Solving Homework

Fall 2022

Type in all your answers under each question using complete, grammatically correct sentences. Use Times 12 font and keep everything single-spaced. Even though tweeting and texting are normal practices with iPhones and such, this is NOT such an event. Full explanations and sentences are required.

Please put effort into this, as it will be graded according to effort and the correctness of your answer with respect to physiological/scientific logic.

Minimum effort and input on your end will be graded with minimum effort and output on my end. For example, when an explanation is asked for, you need to back up your statements with ‘evidence’. A blank number or statement is not an explanation unless you back it up with logic or with data.

Since this is a word document, items will shift as you type. It is your job to keep the organization of this assignment clean by using margins and common sense. For example, don’t start a new heading at the bottom of a page, with the starting paragraph on the next page (in editing, that is sometimes referred to as ‘orphaning’ or ‘decapitation’). Your graph and legend needs to be on a separate page. I like to see a presentation as if you are applying for your dream job.

While collaboration is encouraged, the final presentation should be an individual effort. I can tell when a student is playing the copy/paste game. If a student copies work from another student, both students will receive a zero on this assignment.

Type your name, aligned to the left, at the bottom of each page.

Note : Each question has a point value. They all add up to 50 points. Remember that Your Homework Assignments make up 12.5 % of your lab grade.

Name : ____________________

1. First set of questions

At the start of the semester, we discussed homeostasis. One of the very important aspects of homeostasis is the concept of osmolarity. You may want to go back to lectures from Module 1 and see how osmolarity is calculated (or do a Google search on that).

a. The following Table gives 3 solutions. If the homeostatic value of osmolarity in blood is 290 milliOsmolor, what value ( in mM) must the missing salt be in each of the three solutions in order to make it iso-osmotic with blood ? Briefly explain – back up your claim with your calculated data.

Solution 1 Solution 2 Solution 3
___ mM NaCl 40 mM NaCl 100 mM NaCl
25 mM KCl 10 mM KCl ___ mM KCl
25 mM MgCl2 ___ mM CaCl2 5 mM CaCl2
100 mM Glucose 110 mM Glucose 25 mM Glucose
30 mM Fructose 20 mM Fructose 10 mM Fructose

Your answer here: (5 points)

b. Of the 3 solutions, which one do you think would be the safest one to inject into the vein of a patient and why (explain)?

Your answer here: (3 points)

c. What is a percent (%) solution ? ( seen in first Module lectures )

Your answer here: (2 points)

d. A Physiological Saline solution is a NaCl solution. What % NaCl solution is isotonic with blood and what is the Osmolarity of isotonic saline ? ( or how do you calculate the Osmolarity if you know the % NaCl solution that is isotonic with blood ? Look it up… )

Your answer here: (5 points)

2. Second set of questions

a. The following table shows an Osmotic Fragility test of RBC’s . The data presented are % hemolysis of the RBC’s when exposed to different % NaCl solutions. Sample 1, 2 and 3 are RBC’s from a normal patient, a patient with Sickle Cell anemia and a patient with Hereditary Spherocytosis ( but not in that specific order )

% NaCl Sample 1 Sample 2 Sample 3
__________________________________________________________
0.10 100 100 100
0.20 100 100 85
0.30 98 100 40
0.35 95 98 15
0.40 87 95 5
0.45 58 90 4
0.50 20 80 3
0.55 3 20 2
0.60 0 10 1
0.65 0 5 0.5

Your job is to put this into an excel sheet and graph it. All 3 sets of data need to go into one graph so you can see the differences clearly. When done, copy and paste that graph into this word document. Make sure your Graph has proper labels on X and Y axis and a proper legend to go with it ( see guidelines for first graphing exercise).

Insert Graph on the next page ( make this a nice, half page graph – label your axis – use proper values and provide a nice Legend under the graph. Look in textbooks on how a nice graph looks like or see my previous graphing guidelines. I like to see College level graphing !) . The graph is 15 points.

Question b should thus be started on a new page after the graph !

b. Assuming you were the scientist that obtained these results, provide me now with a one to two page discussion about the results shown in the Table and graph you created. In other words, provide first a brief overview of what the two diseases are ( compare/contrast). Secondly, briefly discuss what an Osmotic Fragility test is and why one would use it. Finally, discuss what the graph tells you for those two diseases when such an Osmotic Fragility test is used and provide possible explanations for the results. Incorporate into the discussion why these graphs have the shape that you observe and You should be able to explain which graph belongs to what patient. This is applied medical physiology .

Your answer/discussion here : (20 points)

Bonus question

Homeostasis requires that the total osmolarity of cells and extracellular medium needs to be the same ( i.e. isotonicity : the total number of non-permeable particles on either side of the membrane needs to be the same) AND that charge neutrality needs to be obeyed. This latter meaning that, the total sum of all negative ions and positive ions, needs to be the same on both sides of the membrane compartments.

Knowing this information, can you solve the following “puzzle” ? If the cell below is in a steady state condition, what is the concentration of K+ inside the cell, and what is the concentration of Impermeable non-electrolytes outside the cell ? (understand the term non-electrolyte).

Na+ = 20 mM Na+ = 140 mM
K+ = unknown in mM K+ = 5 mM
Cl- = 5 mM Cl- = 145 mM
A- (impermeable anions) = 165 mM Impermeable Non-Electrolytes = ???

Show your ‘calculations’ and answers: (5 points)

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