BSC 2086 01 Anatomy and Physiology II Spring 2013 10 Blood Vessel Dynamics 2012 Pearson Education Inc An Introduction to Blood Vessels and Circulation Learning Outcomes 21 2 Explain the mechanisms that regulate blood flow through vessels describe the factors that influence blood pressure and discuss the mechanisms that regulate movement of fluids between capillaries and interstitial spaces 21 3 Describe the control mechanisms that regulate blood flow and pressure in tissues and explain how the activities of the cardiac vasomotor and respiratory centers are coordinated to control blood flow through the tissues 2012 Pearson Education Inc An Introduction to Blood Vessels and Circulation Learning Outcomes 21 4 Explain the cardiovascular system s homeostatic response to exercise and hemorrhaging and identify the principal blood vessels and functional characteristics of the special circulation to the brain heart and lungs 21 5 Describe the three general functional patterns seen in the pulmonary and systemic circuits of the cardiovascular system 21 9 Discuss the effects of aging on the cardiovascular system and give examples of interactions between the cardiovascular system and other organ systems 2012 Pearson Education Inc 21 2 Pressure and Resistance Circulatory Pressure P difference in pressure across the systemic circuit about 100 mm Hg Circulatory pressure must overcome total peripheral resistance R R of entire cardiovascular system 2012 Pearson Education Inc 21 2 Pressure and Resistance Total Peripheral Resistance Vascular resistance Blood viscosity Turbulence 2012 Pearson Education Inc Figure 21 9 Factors Affecting Friction and Vascular Resistance Friction and Vessel Length Internal surface area 1 Resistance to flow 1 Flow 1 Internal surface area 2 Resistance to flow 2 Flow 21 Friction and Vessel Diameter Greatest resistance slowest flow near surfaces Least resistance greatest flow at center Resistance to flow 1 Resistance to flow 16 Vessel Length versus Vessel Diameter Diameter 2 cm Diameter 1 cm Factors Affecting Vascular Resistance Plaque deposit Turbulence 2012 Pearson Education Inc Turbulence Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc Table 21 1 Key Terms and Relationships Pertaining to Blood Circulation 2012 Pearson Education Inc 21 2 Pressure and Resistance An Overview of Cardiovascular Pressures Vessel diameters Total cross sectional areas Pressures Velocity of blood flow 2012 Pearson Education Inc Figure 21 10b Relationships among Vessel Diameter Cross Sectional Area Blood Pressure and Blood Velocity within the Systemic Circuit Cross sectional area cm2 2012 Pearson Education Inc Total cross sectional area of vessels Figure 21 10c Relationships among Vessel Diameter Cross Sectional Area Blood Pressure and Blood Velocity within the Systemic Circuit Average blood pressure mm Hg 2012 Pearson Education Inc Average blood pressure 21 2 Pressure and Resistance Arterial Blood Pressure Systolic pressure Peak arterial pressure during ventricular systole Diastolic pressure Minimum arterial pressure during diastole Why doesn t the diastolic pressure drop to zero when the heart is relaxed 2012 Pearson Education Inc 21 2 Pressure and Resistance Arterial Blood Pressure Pulse pressure Difference between systolic pressure and diastolic pressure Mean arterial pressure MAP MAP diastolic pressure 1 3 pulse pressure For example if the BP is 120 90 MAP 90 1 3 120 90 90 1 3 30 90 10 100 mm Hg 2012 Pearson Education Inc 21 2 Pressure and Resistance Abnormal Blood Pressure Normal 120 80 systolic pressure diastolic presure Hypertension Abnormally high blood pressure Greater than 140 90 Hypotension Abnormally low blood pressure Most cases caused by overly aggressive drug treatment of hypertension 2012 Pearson Education Inc 21 2 Pressure and Resistance Elastic Rebound Arterial walls Stretch during systole Rebound recoil to original shape during diastole Keep blood moving during diastole 2012 Pearson Education Inc 21 2 Pressure and Resistance Pressures in Small Arteries and Arterioles Pressure and distance MAP and pulse pressure decrease with distance from heart Blood pressure decreases with friction Pulse pressure decreases due to elastic rebound 2012 Pearson Education Inc Figure 21 11 Pressures within the Systemic Circuit Systolic Pulse pressure Mean arterial pressure Diastolic mm Hg 2012 Pearson Education Inc 21 2 Pressure and Resistance Venous Pressure and Venous Return Determines the amount of blood arriving at right atrium each minute Low effective pressure in venous system 2012 Pearson Education Inc 21 2 Pressure and Resistance Venous Pressure and Venous Return Low venous resistance is assisted by 1 Muscular compression of peripheral veins Compression of skeletal muscles pushes blood toward heart one way valves 1 The respiratory pump Thoracic cavity action Inhaling decreases thoracic pressure pulls air into lungs and blood into inferior vena cava Exhaling raises thoracic pressure pushes venous blood into right atrium 2012 Pearson Education Inc 21 2 Pressure and Resistance Capillary Pressures and Capillary Exchange Vital to homeostasis Moves materials across capillary walls by Diffusion Filtration Reabsorption 2012 Pearson Education Inc 21 2 Pressure and Resistance Diffusion Movement of ions or molecules From high concentration to lower concentration along the concentration gradient Extra energy is not required for this process 2012 Pearson Education Inc 21 2 Pressure and Resistance Diffusion Routes 1 Water ions and small molecules such as glucose Diffuse between adjacent endothelial cells Or through fenestrated capillaries 1 Some ions Na K Ca2 Cl Diffuse through channels in plasma membranes 2012 Pearson Education Inc 21 2 Pressure and Resistance Diffusion Routes 3 Large water soluble compounds Pass through fenestrated capillaries 3 Lipids and lipid soluble materials such as O2 and CO2 Diffuse through endothelial plasma membranes 3 Plasma proteins Cross endothelial lining in sinusoids sinusoidal capillaries 2012 Pearson Education Inc 21 2 Pressure and Resistance Filtration Driven by hydrostatic pressure from an area of high pressure to an area of low pressure Water and small solutes forced through capillary wall Leaves larger solutes in bloodstream 2012 Pearson Education Inc 21 2 Pressure and Resistance Reabsorption The result of osmotic
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