Biol 216 9 Circulatory System 129-160.pdf

Biol 216 9 Circulatory System 129-160.pdf - What if the...

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5/24/17 1 What if the ventricular action potential had a shorter duration? The flat line between the qrs and the T wave would be shorter if it repolarized sooner. 5/24/17 129 A story… 5/24/17 130
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5/24/17 2 Now that we know how the heart works… We turn our focus to CIRCULATION 5/24/17 131 Blood Pressure Blood Vessels Circulation 5/24/17 132
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5/24/17 3 1. The cuff is pumped up until its pressure is higher than the arterial blood pressure, cutting off the flow of blood through the large artery serving the arm. 2. A stethoscope is placed over the artery just below the cuff, and the pressure in the cuff is slowly released. When cuff pressure drops to the point that blood just begins to flow through the artery, a faint thumping sound is heard in the stethoscope. The sound is produced by turbulence created as spurts of blood pass through the narrowed artery. The pressure read on the meter when the thumping begins is the systolic pressure. 3. The pressure in the cuff is released further until the thumping sound just disappears. At this point, there is no turbulence because the artery is fully open. The pressure read on the meter at this point is the diastolic pressure. At rest, a typical systolic blood pressure in a healthy individual ranges from 110-140mmHg and 60-90mmHg for diastolic blood pressure 5/24/17 133 Systemic circulation : high blood pressure in the arteries, pulsatile. Doesn’t fall to zero between heartbeats. On the rise up, heart is contracting. On the slope down, the heart is relaxing But even when the heart is relaxing, the pressure is still above zero. 5/24/17 134
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5/24/17 4 Pulmonary circuit: pressure is lower Advantages of having two completely separate systems , two completely different pressures. We do not want too much pressure in our lungs. The exchange pathway is shorter with lower resistance : fluid could leaking out of vessels into the lungs 5/24/17 135 Arteries Artery walls Inner endothelial layer Middle layer of smooth muscle Outer layer of elastic fibers (elastin, inconnective tissue) Arterioles (smallest arteries) constrict and dilate Regulate flow andpressure of blood into capillaries 5/24/17 136
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  • Spring '14
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