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Behind the Black Box: Medical Instruments . Why Do We Care? . Medical equipment can be used to understand the human body better. Diagnosis Monitoring Treatment Also 6 Billon Dollar Industry. Part of A Bigger System.
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Why Do We Care? • Medical equipment can be used to understand the human body better. • Diagnosis • Monitoring • Treatment • Also 6 Billon Dollar Industry.
Part of A Bigger System • Throughout human history, engineering has driven the advance of civilization. • Even now, the world has multiple issues on which engineers could be working. • As a result, the National Academy of Engineering (NAE) has defined some challenges facing us in this century.
14 Grand Challenges • Make solar energy economical • Provide energy from fusion • Develop carbon sequestration methods • Manage the nitrogen cycle • Provide access to clean water • Restore and improve urban infrastructure • Advance health informatics • Engineer better medicines • Reverse-engineer the brain • Prevent nuclear terror • Secure cyberspace • Enhance virtual reality • Advance personalized learning • Engineer the tools of scientific discovery
“Lub-Dub” • The “lub” sound comes first in the heartbeat and is the longer of the two heart sounds. • The “lub” sound is produced by the closing of the AV valves at the beginning of ventricular systole. • The shorter, sharper “dub” sound is similarly caused by the closing of the semilunar valves at the end of ventricular systole.
The Cardiac Cycle • Systole: The atria contract and push blood into the ventricles. The ventricles contract to push blood into the aorta and pulmonary trunk. • Diastole: All 4 chambers of the heart are in diastole as blood pours into the heart from the veins. The ventricles fill to about 75% capacity during this phase and will be completely filled only after the atria enter systole.
Pulse Plethysmograph • This pulsatile change in blood pressure results in a value change in the somewhat elastic blood vessels in the body. • A pulse plethysmograph measures volume changes using light transmittance.
Blood Oximetry • Oxygenated blood absorbs light at 660nm (red light), whereas deoxygenated blood absorbs light preferentially at 940nm (infra-red). • Pulse oximeters consist of two light emitting diodes, at 600nm and 940nm, and two light collecting sensors, which measure the amount of red and infra-red light emerging from tissues traversed by the light rays.
Now Something Fun • Divide into 4 groups at the lab tables. • You should have a device called a pulse oximeter on your table. • Take your heart rate without the pulse oximeter first. • Have someone else record your waveform. • Next ….