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

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

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

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

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

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

.75 seconds 1 cardiac cycle

Filling Heart Chambers: Cardiac Cycle LUB= AV valve closing DUB = semilunar valve closing Atrial contraction Mid-to-late diastole (ventricular filling) Ventricular systole (atria in diastole) Early diastole Isovolumetric contraction phase Ventricular ejection phase Isovolumetric relaxation Ventricular filling Left atrium Right atrium Left ventricle Right ventricle 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

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.

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

Pulse Figure 11.18

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.

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

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

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

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

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

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”

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

Effect of Various Factors on Blood Pressure and Heart Rate

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

Causes of changes to PR BP = CO  PR Increasing PR will increase BP Increase PR Decrease PR Narrow Blood Vessel (vasoconstriction) Widen Blood Vessels (vasodialation) Arteriosclerosis Increase Blood Volume Decreased Blood Volume (hemorrhage) BP = CO  PR Increasing PR will increase BP Decreasing PR will decrease BP

Vasoconstriction/Vasodilatation 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

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

BP = CO  PR Increased CO  Increased BP Decreased CO  Decreased BP Change in CO Increase CO Decrease CO Increased pulse rate Decreased pulse rate Exercise ->increased pulse rate

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

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.

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

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

Factors Determining Blood Pressure Figure 11.21

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