A Modular Approach to
Teaching the Engineering
Challenges of Physiology
Gregory J. Sonek
Dept. of Electrical and Computer Engineering
Merrimack College
North Andover, MA
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
•
Background and Introduction
•
Course Structure and Development
• Examples of Themes and Projects
•
Results and Conclusions
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Background and Introduction
“Engineering Challenges in Physiology” is a course offered as part of a
biomedical engineering curriculum with the following goals and objectives:
•
•
•
To provide students with literacy and fluency in basic physiological
processes and systems
To enable students to identify, through an understanding of universal
concepts and themes, engineering challenges i.e. needs and opportunities
for new techniques, devices, and systems at the molecular, cellular, tissue,
and whole body scales
To provide an opportunity for application of course concepts through self
study and exploration
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Course Challenges
Physiology is a highly interdisciplinary subject that crosses the boundaries of
science and engineering. Both the audience and course content present
significant challenges:
•
•
•
Course offered to undergraduates and graduates who are pursuing
• BSBME degree, second major, and minor
• ME, MS, and Ph.D. degrees
• Certificate degree in bioengineering
Draws students that have diverse educational backgrounds and varying
degrees of industrial and professional training. Backgrounds include
• Engineering (electrical, mechanical, chemical, biological)
• Life sciences (biology, premedicine)
• Physics
Students are motivated to leverage existing or prior experiences with
new coursework that will facilitate their involvement in the biomedical field
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Course Challenges
•
•
•
The subject of physiology is vast and diverse
Engineering concepts and themes must be reviewed and applied
Engineering challenges must be identified
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Course Structure and Development
A modular approach was adopted to address course challenges:
•
•
•
•
•
•
Present select topics in physiology in 2 – 3 week intensive modules
for in depth study
Develop common themes and concepts that bridge all systems
Use a combination of lectures, text readings, homework, and
weekly review of current events to engage all students
Draw upon expertise from faculty and researchers in specific
areas of physiology e.g. respiratory, neuro, cardiovascular, renal
Focus on problem solving, identification of problems, and challenges
Use a final project to integrate course concepts and provide an
opportunity for research and self exploration
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
•
Introduction to Engineering in Physiology
Human body as a complex system; sensing, feedback, and control
Physiological parameters, transport, fluid/gas mechanics, chemistry, electrical processes
•
•
•
•
•
•
Cellular Physiology
Cell structure, cell transport, ion channels
Potentials (membrane, action), intracellular signaling, neurotransmission
Neurophysiology
Central and peripheral nervous systems, autonomic and sympathetic processes
Receptors, neural pathways, sensory (auditory, visual) systems
Interfacing with the nervous system, neuro-prosthetics, bionic devices
Respiratory Physiology
Functional anatomy and control of breathing
Mechanics of breathing, gas exchange (diffusion), ventilation/perfusion matching
Cardiovascular Physiology
Basic hemodynamics, electrophysiology, electrocardiography
Mechanical events of the cardiac cycle, peripheral circulation regulation
Cardiac muscle mechanics, molecular cardiology
Renal Physiology
Quantitation of renal transport processes, renal tubular function
Acid/base balance, blood pressure and volume control
Special Topics
Temperature regulation. exercise, high-altitude, and hyperbaric physiologies
•
Final Projects
Student chosen projects in select areas of physiology
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Basic Principles and Common Themes
The course emphasizes many basic principles and themes common across all
physiological systems, including:
•
•
•
•
Energy
Electrochemical potential, metabolism (ATP, glucose, FFA)
Communications
Signaling, receptors, integrated pathways
Information
Audition, vision, tactile sensing, neural processing
Feedback &
Control
Open/closed loop, negative/positive feedback, sensor
integration with chemical and neural systems
•
Transport
Drift, diffusion, passive and active transport, fluids,
gases, ions, solutes
•
Processes
Chemical, mechanical, and electrical processes
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Basic Principles and Common Themes
An example of two principles that applies to many different systems are those
of Ohm’s Law , where resistance represents opposition to flow (y = z x R) and
Potential Energy (storage) represents the capacity for accumulation (y = 1/C z dt)
Electrical
Mechanical
OHM’S LAW
V = IR
F = v Rm
I
CAPACITY
q=CV
x = F Cm
F
x
F
v
Fluidic
Thermal
DP = Q Rf
Dq = Q Rt
Q
DP = P1 – P2
q1
q2
DV = DP Cf
Q = Dq Ct
Q
Chemical
Df = Q Rc
f1
f2
DV
M = V Cc
Df = f1 - f2
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
DP
q2
q1
Universal Concepts and Themes
BASIC CONTROL SYSTEM WITH NEGATIVE FEEDBACK
Input, r
Controller
Action, u
+
Plant
(Controlled
System)
Controller
Feedback
Signal, z
Disturbance, x
Output, y
Feedback
Sensor
CONTROL SYSTEM WITH NEGATIVE AND POSTIVE FEEDBACK
+
Presynaptic
Impulse
+
Na+ Current
Sodium
Conductance
Membrane
Voltage
+
-
Potassium
Conductance
Net
Inward
Current
Membrane
Capacitance
K+ Current
Delay
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Cardiovascular Feedback and Control
INTERVENTION
Arterial Pressure
Increase
Baroreceptor
firing rate
Baroreceptor
stretch
Decrease
Sympathetic Activity
Parasympathetic Activity
a1-adrenergic
receptor activation
Systemic vascular
resistance
b1-adrenergic
receptor activation
Muscarinic
receptor activation
Force of Contraction
Heart Rate
Stroke Volume
Cardiac Output
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Application of Engineering Principles
EXAMPLE: OXYGEN CONSUMPTION
STEP
CHEMICAL & PHYSICAL PRINCIPLES
Alveolar Ventilation
Fluid mechanics of laminar and turbulent flows
Pulmonary Gas
Exchange
Diffusion; Henry’s Law; Law of Mass Action
Allosteric conformational effects on hemoglobin
Oxygenated Blood
Circulation
Fluid mechanics; Physical chemistry of
hemoglobin
Extravascular Oxygen
Distribution
Diffusion
Oxygen Transport into
Cells & Mitochrondria
Diffusion; Henry’s Law; Mass Action
Cell Respiration
Kinetics of electron transport chains
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Analysis of Engineering and Clinical Data
OBJECTIVE: To apply course engineering and physiological concepts to the
solution of problems derived from real clinical or experimental data.
EXAMPLE: To investigate the mechanics of breathing through the concepts of flow
and pressure-flow relationships. Data is derived from spirometer and pneunotachograph measurements
• IDENTIFY PATIENT P - V CURVES
Emphysema
Asthma
dV’
Time (sec)
Volume
Pressure (cm H2O),
Flow (L/sec), or Volume (L)
• FIND RESISTANCE BY THE ISOVOLUME METHOD
Near-Drowning
dP
Pressure
Flow (V’)
Volume (Integrated Flow)
Pleural Pressure
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Analysis of Physiological Data
EXAMPLE: To explore the role that the kidneys and lungs play in acid/base balance
and identification of various acid/base disorders, including metabolic and
respiratory acidosis and alkalosis
•
•
Henderson – Hasselbalch Eqn.
Davenport Diagram
pH = pK + log
[HCO3-]
0.03 x PCO2
pH = Kidneys
Lungs
•
Sample Conditions
A = Uncompensated metabolic acidosis
B = Metabolic alkalosis and respiratory
acidosis
Plasma [HCO3] (mEq/l)
PCO2 60
35
PCO2 40
30
B
PCO2 20
(mm Hg)
25
20
Buffer
Line
A
15
10
7.0
7.2
7.4
7.6
Plasma pH
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
7.8
Engineering Concepts and Challenges
To further develop the theme of engineering challenges, modules use
take home assignments that pose open ended questions or problems for
which there are no current solutions. Some examples include:
•
•
•
Continuous Measurement of Airway Obstruction during Sleep
Requires a method for analyzing nasal flow and chest/abdomen movement
to diagnose hypopnea (reduction of airflow) in patients with obstructive sleep
apnea (OSA)
Implantable Gas Exchanger (Artificial Lung) as Lung Transplantation Alternative
Considers the design of an artificial gas exchanger as an alternative to extracorporeal oxygen devices for patients with advanced lung disease
Changes in Fluid Volumes and Osmolarities
Considers the changes to intracellular and extracellular fluid volumes and
osmolarities in marathon runners who compete on a hot day, rehydrate only with
pure water, and suffer muscle cramping near the end of a race
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Final Projects
SUGGESTED TOPIC
STUDENT PROJECTS
Space Physiology
“Physiological effects of fluid shifts on the
cardiovascular system during space travel”
Neonatal Physiology
“Neurology and the human auditory system”
“Effects of neutropenia in the neonate”
“Respiratory physiology of preterm births”
Sports Medicine Physiology
“Turning Michael Johnson into a marathon
runner”
“Performance monitoring in cyclists: VO2
max, lactate threshold, nutrition, muscle
function, and power training”
High-Altitude Physiology
“Engineering challenges in high-altitude
physiology”
Hyperbaric Medicine
“Physiology under hyperbaric conditions”
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Examples
“Performance Monitoring in Cyclists: VO2 max, lactate threshold,
nutrition, muscle function, and power training”
OBJECTIVE: To understand VO2 max and the factors that affect it, from basic
metabolic processes and barriers, to muscle types, nutrition, training regimens,
and devices used to monitor performance
Lactate Threshold Measurement
Lactic Acid in Metabolism
Do You Prefer White or Dark Meat?
• Chickens also have slow and fast twitch fibers
• Dark meat in the legs is mostly slow twitch
• Good for walking and standing
• Constant and low energy
• White meat in wings and breasts are
mostly fast twitch
• Used in brief busts of flight
• Lots of energy for short period of
time
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Examples
“Physiology under Hyperbaric Conditions”
OBJECTIVE: To understand the effects of pressure on the human body, including
Dalton’s Law, tissue saturation, nitrogen narcosis, and the neurological effects of
gas partial pressures (lipid bilayer alteration, modified neuronal firing rates)
Pressure - Partial Pressure
Other
CO2
O2
Consequences of Gas Partial Pressure
Alteration of Lipid Bilayer
Governed by Dalton’s law:
P = pN2+pO2+pCO2+…+pn
Partial Pressures
@ 1 ATA
Partial Pressures
@ 4 ATA
N2
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Results and Conclusions
•
•
•
•
A modular approach to the study of engineering and its challenges in
physiology has proven to be a successful course model
The course focuses on concepts and themes that are common to
different physiological systems (cellular, neuro, respiratory, CV, renal)
It has the goal of helping students identify engineering challenges (needs
and opportunities) for new techniques, devices, and systems from the
molecular to whole body scales
The strength of the course lies in its breadth, interdisciplinary nature,
and expertise brought by a diverse group of faculty and lecturers with
backgrounds in engineering, medicine, R&D, and clinical applications
ASEE New England Section 2006 Annual Conference, March 17-18, 2006
Acknowledgments
We are grateful to all the participating faculty, researchers, and students
at Tufts University who made this work possible:
Prof. David Kaplan
Dept. of Biomedical Engineering
Prof. Andrew Hoffman
School of Veterinary Medicine and
Lung Function Testing Laboratory
Prof. Larry Engelking
Dept. of Biomedical Sciences and
School of Veterinary Medicine
Prof. Eunice Bloomquist
Dept. of Physiology and School of Medicine
Dr. Michael Mendelsohn
Molecular Cardiology Institute and NEMC
Dr. Ron Risso
Inner Sea Tech
BME Students
Brian Orrick, Jason Waterman, Clemens Alt,
Leonardo Angelone
ASEE New England Section 2006 Annual Conference, March 17-18, 2006