Exercise 22: Human Cardiovascular Physiology- Blood Pressure and Pulse Determination

1. Exercise 22: Human Cardiovascular Physiology- Blood Pressure and Pulse Determination

2. Cardiac Cycle aortic pressure ventricular pressure atrial pressure ventricular volume EKG heart sounds DUB LUB

3. Terms • Systole = contraction of ventricles • Diastole = relaxation of ventricles • Cardiac cycle= events of one complete heartbeat, during which both atria and ventricles contract and then relax

4. AV valves closed during ventricular systole AV valves open during ventricular diastole AV valves open when ventricular pressure is less than atrial pressure. AV valves close when the pressure inside the ventricle rises

5. Semilunar valves closed during ventricular diatole Semilunar valves open during ventricular systole Semilunar valves open when ventricular pressure exceeds that of the large arteries leaving the heart. Semilunar valves close when ventricles relax at the end of systole to prevent backflow

6. Pressure in the heart is highest during ventricular systole. Pressure in the heart is lowest during ventricular diastole.

7. .75 seconds 1 cardiac cycle

8. Left atrium Right atrium Left ventricle Right ventricle Ventricularfilling Atrialcontraction Isovolumetriccontraction phase Ventricularejection phase Isovolumetricrelaxation Mid-to-late diastole(ventricular filling) Ventricular systole(atria in diastole) Early diastole Filling Heart Chambers: Cardiac Cycle LUB= AV valve closing DUB = semilunar valve closing LUB DUB is caused by the closing of the heart valves- the first sound is longer and louder and the second sound, which is short and sharp Figure 11.7

9. Abnormal Sounds might indicate……. • Valve deformities that can seriously hamper cardiac function and ultimately weaken the heart. • Abnormalities in the conduction system of the heart. • Inadequate blood supply to the heart. “Heart block" or "AV block." is when the electrical impulse signal from the heart's upper to lower chambers is impaired or doesn't transmit. Cardiac ischemia is the name for lack of blood flow and oxygen to the heart muscle. Heart valve problems:Stenosis is when heart valves don't open enough to allow the blood to flow through as it should. Regurgitation is when the heart valves don't close properly and allow blood to leak through. Mitral valve prolapse is when the valve leaflets bulge or prolapse back into the upper chamber. They may not close properly and blood may leak back through.

10. Pulse • Pulse • Alternating surges of pressure (expansion then recoil) in an artery that occur with each beat of the left ventricle. • Monitored at “pressure points” in arteries where pulse is easily palpated • Pulse averages 70–76 beats per minute at rest

11. Pulse Figure 11.18

12. Has an artery or vein been cut? How to tell. • Blood from a vein would be darker than from an artery.If you punctured an artery or vein then the blood flow would continue until you put pressure on it to allow for the blood to clot. • An arterial cut will spurt blood. Vein will just flow out.

13. Blood Pressure • DEFINITION: The pressure the blood exerts against the inner blood vessel wall. • Systolic pressure— pressure in the arteries at the peak of ventricular contraction • Diastolic pressure— pressure in the arteries when ventricles relax

14. Measuring Arterial Blood Pressure with “Sphygomomanometer” Name of instrument used in determining blood pressure. Figure 11.20a

15. Korotkoff Sounds - Auscultatory blood pressure measurement showing onset of Korotkoff sounds at systolic pressure, and diminishing sounds as diastolic pressure is reached. Note that last (diastolic) pulse is barely audible but clearly visible. Sounds of Korotkoff Auscultation is the technical term for listening to the internal sounds of the body, usually using a stethoscope Are sounds caused by the resumption of blood flow into the forearm. onset of Korotkoff sounds at systolic pressure, and diminishing sounds as diastolic pressure is reached. Figure 11.20b http://www.thinklabsmedical.com/stethoscope_community/Sound_Library

16. Systolic Sound The systolic sound is caused by the blood first spurting through the constricted artery

17. The disappearance of sound No sound because the blood flows freely because the artery is no longer compressed.

18. Blood Pressure • Write systolic pressure first and diastolic last • 120/80 means the • “systolic pressure of 120 mm Hg and diastolic pressure is 80 mm Hg”

19. Comparison of Blood Pressures in Different Vessels Highest Pressure • Venous pressure is lower than arterial pressure • Veins are farther away from ventricular ejection (blood forced out of heart) Lowest Pressure Figure 11.19

20. Effect of Various Factors on Blood Pressure and Heart Rate

21. Blood Pressure: Effects of Factors • BP is blood pressure • CO is the amount of blood pumped out of the left ventricle per minute • PR is peripheral resistance, or the amount of friction blood encounters as it flows through vessels • BP = CO  PR Increasing CO or PR will increase BP Decreasing CO or PR will decrease heart rate

22. Causes of changes to PR BP = CO  PR Increasing PR will increase BP Decreasing PR will decrease BP

23. Narrowing of the blood vessels resulting from contracting of the muscular wall of the vessels Vasoconstriction/Vasodilatation Temperature: Cold  Vasoconstriction Warm  Vasodilatation • Sympathetic NS (exercise or fright) • General vasoconstriction • Vasodilatation of blood vessels of skeletal muscle Bigger diameter of blood vessel = lower BP Smaller diameter of blood vessel = higher BP

24. Viscosity • thickness and stickiness: a thick and sticky consistency or quality Increased viscosity = higher BP Decreased viscosity = lower BP Low Viscosity High Viscosity

25. BP = CO  PR • Increased CO  Increased BP • Decreased CO  Decreased BP • Change in CO

26. Blood Pressure: Effects of Factors • Neural factors • Autonomic nervous system adjustments • (sympathetic division) • Standing suddenly blood pools in legs and feet BP drops BARORECEPTORS activated Vasoconstriction BP rises

27. Reclining or Standing? • If you move from a seated or supine position to a standing position, there may be a momentary drop in your blood pressure. This drop occurs because your body experiences a temporary drop in blood volume as 300 to 800 mL of blood pools in your legs. However, special cells called baroreceptors sense this drop and signal the heart to beat faster. Blood vessels will then contract and increase pressure to pump the blood upward. Thus, after an initial drop, you experience a rise in blood pressure when moving from a supine position to standing.

28. BP and Exercise • During exercise, the systolic pressure increases progressively as the cardiovascular system attempts to deliver more oxygen to the working muscles. The diastolic pressure (the lower number) should stay about the same, or decrease slightly, thanks to the dilated blood vessels in the working muscles that help heat escape

29. Blood Pressure: Effects of Factors • Temperature • Heat has a vasodilating effect • Cold has a vasoconstricting effect • Chemicals • Various substances can cause increases or decreases • Diet

30. Factors Determining Blood Pressure Figure 11.21

31. Variations in Blood Pressure • Normal human range is variable • Normal • 140–110 mm Hg systolic • 80–75 mm Hg diastolic • Hypotension • Low systolic (below 110 mm HG) • Often associated with illness • Hypertension • High systolic (above 140 mm HG) • Can be dangerous if it is chronic