BE211 Lab Agenda
• Lab Rules
• What is going on in Lab 1
• Overview of EKG and Chapter 9 Bioelectric Measurement
• (optional) Stay for common op-amp configuration review / Q&A
• (optional) MultiSim Installation for prelab / Q&A
Why EKG?
• Non-invasive (can be done
on each other)
• Cardiovascular disease –
underlying cause of
approximately 50% of
deaths in U.S.
Heart Anatomy
• Two atria – receiving
chambers
• Two ventricles – pumping
chambers
• Ventricles have much thicker
muscle layer – why?
Heart Anatomy
• Two atrioventricular (AV)
valves – allow blood to flow
from atria to ventricles
• Two semilunar valves – allow
blood to flow from ventricles
to major arteries
• Heart murmurs caused by
leaky valves
Cardiac Cycle
• Systole – contraction of
cardiac muscle in heart
chamber
• Diastole – relaxation of
cardiac muscle in heart
chamber
Excitable Cells
• Only nerve cells and
muscle cells are
excitable cells
• Voltage changes caused
by opening gated-ion
channels – produces
current flow
• When muscle cells
become electrically
excited (stimulated),
then they mechanically
contract
Take home message: spread of electrical activity through
heart (cardiac muscle cells) leads to mechanical contraction
and pumping of blood
Cardiac muscle cells come in two varieties
• Pacemaker cells (SA, AV
node) – responsible for
coordinated spread of
electrical activity through
heart (autorhythmic); 1% of
cells
• Contractile cells –
responsible for mechanical
pumping of blood (create
force); 99% of cells. They are
‘electrically coupled’ to each
other (neighboring cells)
Lead II = Lead I + Lead III (based on KVL)
0 < t < 70ms
Time
Voltage
70ms < t < 140ms
Time
Voltage
140ms < t < 200ms
Time
Voltage
200ms < t < 250ms
Time
Voltage
250ms < t < 400ms
Time
Voltage
Time
Lab 1
• Groups of 2-3 students
• Three Parts…
• Part I – Instrumentation amplifier (since EKG is differential input signal)
• Part II – Bandpass filter
• Part III – Fine tuning and digitize signal to MATLAB, calculate BPM
Deliverables
• Pre-lab simulation using MultiSim
• Written calculation of theoretical outcomes
• Good practice for circuit construction – Planning, Layout, Neat wiring
• Circuit design, evaluation and validation, improvement – along with
justification and explanations
• Digital lab notebook at the end
Chapter 9 Intro…
• To the textbook