Cardiovascular II
Post on 22-Feb-2016
66 Views
Preview:
DESCRIPTION
Transcript
Cardiovascular II
Outline
• Cardiac Cycle• Cardiac Output– Stroke Volume– Heart Rate
• Fetal Circulation• Blood Vessels• Blood Flow• Blood Pressure• Circulatory System Response to Exercise
Cardiac Cycle
• Cardiac cycle refers to all events associated with blood flow through the heart
Phases of the Cardiac Cycle
Figure 19.19b
Phases of the Cardiac Cycle
Figure 19.19a
Cardiac Output (CO) and Reserve• CO is the amount of blood pumped by each
ventricle in one minute
• CO = HR x SV
Regulation of Stroke Volume
Factors Affecting Stroke Volume
• Preload
• Contractility
• Afterload
Preload
End Diastolic Volume
Contractility
Figure 12.27
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
Afterload
Regulation of Heart Rate: Autonomic Nervous System
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
Ion Imbalances
• Hypocalcemia
• Hypercalcemia
• Hypernatremia
• Hyperkalemia
Congestive Heart Failure (CHF)
• Congestive heart failure (CHF), caused by:– Coronary atherosclerosis
– Increased blood pressure in aorta
– Successive myocardial infarcts
– Dilated cardiomyopathy (DCM)
Blood Vessels
Generalized Structure of Blood Vessels
Figure 20.1b
Blood Flow
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
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
Thought Questions
Radius Effects
Figure 12.21
Blood Pressure (BP)
• Force per unit area exerted on the wall of a blood vessel by its contained blood
Systemic Blood Pressure
Figure 20.5
Figure 12.30
Figure 12.31
Capillary Blood Pressure
Figure 12.40
Figure 12.41
Figure 12.47
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
Figure 12.45
Thought Question
Control of Blood Pressure
• Affecting Total Peripheral Resistance
• Affecting Cardiac Output– Affecting Stroke Volume– Affecting Heart Rate
• Affecting Total Blood Volume
Figure 12.53
Baroreceptor Activity
Total Peripheral Resistance Local Control
Local Control
Total Peripheral resistanceNeural & Hormonal Control
Total Peripheral Resistance Summary
Stroke Volume
Heart Rate
Short Term Regulation - Summary
Long Term Regulation
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
Figure 12.56
Figure 12.59
Thought Question
• What would happen if all of the vessels in your body vasodilated at the same time?
Response to Exercise
Figure 12.61
Figure 12.62
Figure 12.63
Figure 12.64
Figure 12.65
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?
Summary
• Cardiac Cycle• Cardiac Output– Stroke Volume– Heart Rate
• Fetal Circulation• Blood Vessels• Blood Flow• Blood Pressure• Circulatory System Response to Exercise
top related