Fundamentals of Bioengineering (BIOE252)
Conservation Principles in Bioengineering - Textbook Preview
Chapter 1 - Introduction to Engineering Calculations | Chapter 2 - Foundations of Conservation Principles |
Chapter 3 - Conservation of Mass | Chapter 4 - Conservation of Energy |
Chapter 5 - Conservation of Charge | Chapter 6 - Conservation of Momentum | Chapter 7 - Case Studies



Chapter 7 - Case Studies

 

OVERVIEW

One unique feature of this manuscript is the inclusion of three case studies in Chapter 7 that are designed to bridge the applications of the mass, momentum, charge, and energy accounting and conservation equations in biomedical systems.  The case studies include the following:

 

·       The heart and blood circulation

·       The lungs and a heart-lung bypass machine

·       The kidneys and dialysis 

 

We explicitly chose to include these systems since they had physical phenomena at both the cellular and tissue levels.   Three worked examples are included in each case study in addition to appropriate physiological background.  Each has 10-20 homework problems; many of the homework problems are very open-ended and require considerable research on the part of the students.

 

 

EXAMPLE PROBLEMS

 

Kidney

Modeling the Nephron

 

In this part, you will develop a sophisticated model of the nephron.  Engineering principles and processes should drive the selection of the units in your model nephron.  Major chemical constituents should be identified and tracked through the nephron.  Understanding how chemical constituents are processed illuminates how the kidney “works.”

 

1.     (G) The nephron is the basic functional unit of the kidney.  Draw and label a diagram of the nephron, including its major functional units.  Describe the role of each major functional unit.

 

2.     (G) Model the nephron as a multi-unit system containing 6-10 units.  For example, the Bowman’s Capsule could be a unit.  Identify the primary engineering concept (e.g. filtration, reabsorption, etc.) that occurs in each of the units in your model nephron.  Discuss the primary feature or characteristic that drove the selection of each unit.

 

3.     (G) Draw appropriate streams to connect the units.  Determine the flow rate in each stream.  (You may need to gather physiological data from books and journals.)

 

4.     (M) Identify 8 major chemical components in the blood that are processed in the nephron.  You must consider water, bicarbonate, sodium, and urea.  Develop mass balances on each of the chemical constituents.  Determine the concentration of each of these components in each of the streams.  (Again, you will need to gather data from books and journals.  Using a computer may be helpful.)  Present your data in a concise way, such as a table.

 

5.     (M) Can the chemical components from Question 4 be grouped into classes of compounds based on their patterns of movement through the nephron?  If so, describe.

 

6.     (M) Condense the 6-10 unit model of the nephron into only 2-4 units.  Describe each unit and the engineering concept(s) that occurs in each of the units.  Justify your selection in light of the conclusions from Question 5.

 

 

Lungs

Modeling the Lungs

 

1.     (M) We have shown that the balances in Example 7A.2 are flawed because the volume of air inspired did not equal the volume of air expired.  Report the partial pressure, volume, and percent composition of each gas in each compartment for one full respiratory cycle (inhalation and exhalation) assuming that inspired air is at 745 mmHg while expired air is at 784 mmHg.

 

2.     (M) Use your multi-component model above to determine the composition of alveolar air just after inhalation (but before exhalation) taking into account the dead space in the lungs and trachea.  Assume complete mixing within each compartment of your model upon inhalation.  Assume complete mixing between all compartments of your model upon exhalation. 

 

3.     (M) Why are the compositions of alveolar air from Question 2 and the exhaled air from Question 1 (or Example 7A.2) different?  How much of an effect does the dead space air have on the composition of the exhaled air?

 

4.     (M) How could this model be improved?  In other words, what changes could be made to create a model that is more accurate or applicable to a wider range of situations?