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Cardiovascular II
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Outline Cardiac Cycle Cardiac Output Fetal Circulation Blood Vessels
Stroke Volume Heart Rate Fetal Circulation Blood Vessels Blood Flow Blood Pressure Circulatory System Response to Exercise
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Cardiac Cycle Cardiac cycle refers to all events associated with blood flow through the heart
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Phases of the Cardiac Cycle
Figure 19.19b
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Phases of the Cardiac Cycle
Figure 19.19a
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Cardiac Output (CO) and Reserve
CO is the amount of blood pumped by each ventricle in one minute CO = HR x SV
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Regulation of Stroke Volume
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Factors Affecting Stroke Volume
Preload Contractility Afterload
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Preload
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End Diastolic Volume
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Contractility
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Figure 12.27
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Afterload The pressure that must be overcome for the ventricles to eject blood Can be important in people with high blood pressure because it reduces the ability of the ventricles to eject blood
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Afterload
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Regulation of Heart Rate: Autonomic Nervous System
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Chemical Regulation of the Heart
The hormones epinephrine and thyroxine increase heart rate Intra- and extracellular ion concentrations must be maintained for normal heart function
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Ion Imbalances Hypocalcemia Hypercalcemia Hypernatremia Hyperkalemia
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Congestive Heart Failure (CHF)
Congestive heart failure (CHF), caused by: Coronary atherosclerosis Increased blood pressure in aorta Successive myocardial infarcts Dilated cardiomyopathy (DCM)
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Blood Vessels
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Generalized Structure of Blood Vessels
Figure 20.1b
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Blood Flow
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Resistance Resistance – opposition to flow
Measure of the amount of friction blood encounters as it passes through vessels Generally encountered in the systemic circulation Referred to as peripheral resistance (PR) The three important sources of resistance are blood viscosity, total blood vessel length, and blood vessel diameter
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Resistance Factors: Viscosity and Vessel Length
Resistance factors that remain relatively constant are: Blood viscosity – thickness or “stickiness” of the blood Blood vessel length – the longer the vessel, the greater the resistance encountered
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Thought Questions
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Radius Effects
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Figure 12.21
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Blood Pressure (BP) Force per unit area exerted on the wall of a blood vessel by its contained blood
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Systemic Blood Pressure
Figure 20.5
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Figure 12.30
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Figure 12.31
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Capillary Blood Pressure
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Figure 12.40
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Figure 12.41
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Figure 12.47
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Venous Blood Pressure Venous BP is steady and changes little during the cardiac cycle The pressure gradient in the venous system is only about 20 mm Hg A cut vein has even blood flow; a lacerated artery flows in spurts
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Figure 12.45
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Thought Question
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Control of Blood Pressure
Affecting Total Peripheral Resistance Affecting Cardiac Output Affecting Stroke Volume Affecting Heart Rate Affecting Total Blood Volume
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Figure 12.53
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Baroreceptor Activity
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Total Peripheral Resistance Local Control
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Local Control
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Total Peripheral resistance Neural & Hormonal Control
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Total Peripheral Resistance Summary
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Stroke Volume
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Heart Rate
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Short Term Regulation - Summary
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Long Term Regulation
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Circulatory Shock Circulatory shock – any condition in which blood vessels are inadequately filled and blood cannot circulate normally Results in inadequate blood flow to meet tissue needs Three types include: Hypovolemic shock Vascular shock Cardiogenic shock
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Figure 12.56
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Figure 12.59
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Thought Question What would happen if all of the vessels in your body vasodilated at the same time?
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Response to Exercise
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Figure 12.61
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Figure 12.62
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Figure 12.63
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Figure 12.64
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Figure 12.65
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Thought Questions Take Home Exam Extra Credit
What are some of the methods of treating high blood pressure and how do they affect blood pressure? Why do they recommend exercise to decrease high blood pressure?
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Summary Cardiac Cycle Cardiac Output Fetal Circulation Blood Vessels
Stroke Volume Heart Rate Fetal Circulation Blood Vessels Blood Flow Blood Pressure Circulatory System Response to Exercise
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