BSC2086 A P II Exam 3 Study Guide Lesson 10 Blood Vessel Dynamics Circulatory Pressure P difference in pressure across the systemic circuit o 100 mmHg Circulatory pressure MUST overcome total peripheral resistance R resistance of entire cardiovascular system Total Peripheral Resistance o Vascular resistance o Blood Viscosity o Turbulence 1 BSC2086 A P II Exam 3 Study Guide Cardiovascular Pressures 2 BSC2086 A P II Exam 3 Study Guide Pressure depends on o Vessel diameters o Total cross sectional areas o Pressures o Velocity of blood flow Arterial Blood Pressure o Systolic Pressure Peak arterial pressure during ventricular systole o Diastolic Pressure Minimum arterial pressure during diastole Why doesn t the diastolic pressure drop to zero when the heart is relaxed at the end of diastole Elastic fiber stretching recoiling o Pulse Pressure Difference between systolic pressure and diastolic o Recoil squeezes blood and provides pressure pressure o Mean Arterial Pressure MAP MAP Diastolic Pressure 1 3 Pulse Pressure Ex If BP is 120 90 o MAP 90 1 3 120 90 100 mmHg Normal Blood Pressure 120 80 systolic pressure diastolic pressure Abnormal Blood Pressure Hypertension Hypotension o Hypertension Abnormally high blood pressure Greater than 140 90 o Hypotension Abnormally low blood pressure Less common than hypertension 3 BSC2086 A P II Exam 3 Study Guide Mostly caused by overly aggressive drug treatment of hypertension Elastic Rebound o Arterial walls Stretch during systole Rebound recoil to original shape during diastole Keep blood moving during diastole Pressures in Small Arteries and Arterioles o Pressure distance MAP and pulse pressure decrease with distance from heart Blood pressure decreases with friction Pulse pressure decreases due to elastic rebound By time blood reaches precapillary sphincter NO pressure fluctuations remain Venous Pressure and Venous Return Determines the amount of blood arriving at right atrium each minute o Low effective pressure in venous system o Low venous resistance is assisted by Muscular compression of peripheral veins Compression by skeletal muscles pushes blood toward heart one way valves Respiratory Pump thoracic cavity action Inhaling decreases thoracic pressure o Pulls air into lungs blood into inferior vena cava Exhaling increases thoracic pressure o Pushes venous blood into right atrium Why not backwards away from heart 4 BSC2086 A P II Exam 3 Study Guide Squeezes veins have one way valves so blood goes only one direction back to the heart Capillary Pressures and Capillary Exchange o Vital to homeostasis o Moves materials across capillary walls by Diffusion Filtration Reabsorption o Diffusion Movement of ions or molecules from high concentration to lower concentration along the concentration gradient Extra energy NOT required for this process Diffusion Routes Water ions and small molecules i e glucose o Diffuse between adjacent endothelial cells o Or through fenestrated capillaries Some ions Na K Ca2 Cl o Diffuse through channels in plasma membranes Large water soluble compounds o Pass through fenestrated capillaries Lipids lipid soluble materials i e O2 CO2 o Diffuse through endothelial plasma membranes Membrane made of phospholipids Plasma proteins o Cross endothelial lining in sinusoids Ex Sinusoidal capillaries in liver o Filtration Water and small solutes forced through capillary wall Leaves larger solutes in bloodstream Driven by hydrostatic pressure from an area of higher pressure to an area of lower pressure o Reabsorption Result of osmotic pressure OP Blood Colloid Osmotic Pressure BCOP Oncotic Pressure Caused by suspended blood proteins that are too large to cross capillary walls Equals pressure required to prevent osmosis Draws fluid back into the capillaries 5 BSC2086 A P II Exam 3 Study Guide o Interplay between filtration and reabsorption Ensures that plasma interstitial fluid are in constant communication and mutual exchange Accelerates distribution of Assists in the transport of Nutrients hormones and dissolved gases throughout tissues Insoluble lipids tissue proteins that cannot enter bloodstream by crossing capillary walls Has a flushing action that carries bacterial toxins and other chemical stimuli to disease Lymphatic tissues organs responsible for providing immunity to Net Hydrostatic Pressure P between inside outside of capillary Forces water out of solution o Out of capillary into interstitial fluid Net Osmotic Pressure Forces water into solution o From outside capillary to inside capillary Both net hydrostatic pressure AND net osmotic pressure control filtration and reabsorption through capillaries o Factors that contribute to net hydrostatic pressure Capillary Hydrostatic Pressure CHP Interstitial Fluid Hydrostatic Pressure IHP o Net capillary hydrostatic pressure tends to push water solutes out of capillaries and into interstitial fluid o Net Capillary Colloid Osmotic Pressure Is the difference between Blood Colloid Osmotic Pressure BCOP o and Interstitial Fluid Colloid Osmotic Pressure ICOP Pulls water and solutes into a capillary from interstitial fluid 6 BSC2086 A P II Exam 3 Study Guide Net Filtration Pressure NFP The difference between net hydrostatic pressure and net osmotic pressure o NFP CHP IHP BCOP ICOP o Under normal conditions IHP ICOP so the equation can be simplified NFP CHP BCOP Capillary Exchange o At arterial end of capillary NFP 0 Fluid moves out of capillary into interstitial fluid o At venous end of capillary NFP 0 Fluid moves into capillary out of interstitial fluid o Transition point between filtration and reabsorption is closer to venous end than arterial end o Capillaries filter more than they reabsorb Excess fluid enters lymphatic vessels Capillary Dynamics o Hemorrhaging reduces CHP NFP Increases reabsorption of interstitial fluids recall of fluids o Dehydration increases BCOP Because it increases blood volume Accelerates reabsorption o Increase in CHP or decrease in BCOP Fluid moves out of blood Builds up in peripheral tissues Edema results from starvation liver disease plasma proteins not made Cardiovascular Regulation Tissue Perfusion Blood flow through the tissues o Carries O2 nutrients to tissues and organs o Carries CO2 and wastes away o Affected by Cardiac output 7 BSC2086 A P II Exam 3 Study Guide Peripheral resistance Blood pressure Cardiovascular regulation changes blood flow to a specific area o At an appropriate time o o Without changing blood pressure and blood flow to vital organs
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