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 AV valves open during ventricular systole 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 Semilunar valves open during ventricular diatole 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.
1 cardiac cycle
Fil ing Heart Chambers: Cardiac Cycle LUB= AV valve Left atrium closing Right atrium DUB = semilunar valve closing Left ventricleRight ventricle Ventricular Atrial Isovolumetric Ventricular Isovolumetric filling contraction contraction phase ejection phase relaxation Mid-to-late diastole Ventricular systole Early diastole (ventricular filling) (atria in diastole) LUB DUB is caused by the closing of the heart valves- the first sound is longer and louder and the second sound, w Fi h g i u c re h 11.7 is short and sharp
Abnormal Sounds might indicate…….1.Valve deformities that can seriously hamper cardiac function and ultimately weaken the heart.2.Abnormalities in the conduction system of the heart.3.Inadequate blood supply to the heart. “Heart block" or "AV block." is when the electrical impulse Cardiac ischemia is the name signal from the heart’s upper to for lack of blood flow and lower chambers is impaired or oxygen to the heart muscle. doesn’t transmit. 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 tel . 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 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
Comparison of Blood Pressures in Different Vessels Figure 11.19
Measuring Arterial Blood Pressure with Sphygomomanometer 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. Auscultation is the technical term for listening to the internal sounds of the body, usually Sounds ousifn K g a steth ooscoro pe tkoff Sounds caused by the resumption of blood flow into the forearm. Auscultatory blood pressure measurement showing 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
Blood Pressure Write systolic pressure first and diastolic last (120/80 mm Hg) Pressure in blood vessels decreases as distance from the heart increases…..veins are further away from the heart than arteries are.
Blood Pressure: Effects of Factors BP is blood pressure BP is affected by age, weight, time of day, exercise, body position, emotional state 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 Narrowing of blood vessels and increased blood volume increases PR BP = CO × PR
Blood Pressure: Effects of Factors Neural factors Autonomic nervous system adjustments (sympathetic division) Renal factors Regulation by altering blood volume Renin—hormonal control
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