AP2 EXAM 3 STUDY GUIDE 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 Lesson 10 Blood Vessel Dynamics Pressure and Resistance Circulatory Pressure Total Peripheral Resistance Vascular resistance Blood viscosity Turbulence Dialated blood vessel blood inside not touching wall receives less friction Constricted blood vessel more blood brushes wall to increase resistance Go over vocab Small changes in r have big effects on R as r increases R decreases An Overview of Cardiovascular Pressures Vessel diameters Total cross sectional areas Pressures Velocity of blood flow Slide 11Note the greatest cross sectional area is in the capillaries Slide 12 Note the largest drop in BP occurs at the arterioles resistance vessels 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 relaxes at the end of diastole Because of elastic arteries elastic fibers stretch and recoil Pulse pressure Difference between systolic pressure and diastolic pressure Mean arterial pressure MAP know this formula MAP diastolic pressure 1 3 pulse pressure i e BP 120 90 MAP 90 1 3 120 90 100 mmHg Abnormal Blood Pressure hyper hypotension Normal 120 80 systolic pressure diastolic presure Hypertension Abnormally high blood pressure Greater than 140 90 Hypotension Abnormally low blood pressure treatment of hypertension Elastic Rebound helps normalize BP Arterial walls Stretch during systole Rebound recoil to original shape during diastole Keep blood moving during diastole Less common than hypertension mostly caused by overly aggressive drug 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 By the time blood reaches precapillary sphincter no pressure fluctuations remain Slide 18 Arterioles greatest drop in pressure Venous Pressure and Venous Return Determines the amount of blood arriving at right atrium each minute Low effective pressure in venous system Low venous resistance is assisted by 1 Muscular compression of peripheral veins Compression by skeletal muscles pushes blood toward heart one way valves 2 The respiratory pump Thoracic cavity action Inhaling decreases thoracic pressure pulls air into lungs and blood into inferior vena cava less pressure on veins Exhaling raises thoracic pressure pushes venous blood into r atrium decrease in volume not backwards Capillary Pressures and Capillary Exchange Vital to homeostasis Moves materials across capillary walls by Diffusion Filtration fenestrated capillaries Reabsorption Diffusion Movement of ions or molecules Does not require excess energy Diffusion Routes From high concentration to lower concentration along the concentration gradient 1 Water ions and small molecules such as glucose Diffuse between adjacent endothelial cells Or through fenestrated capillaries 2 Some ions Na K Ca2 Cl Diffuse through channels in plasma membranes 3 Large water soluble compounds Pass through fenestrated capillaries 4 Lipids and lipid soluble materials such as O2 and CO2 Diffuse through endothelial plasma membranes 5 Plasma proteins Cross endothelial lining in sinusoids i e sinusoidal capillaries in liver Filtration Driven by hydrostatic pressure from an area of high pressure to an area of lower pressure Water and small solutes forced through capillary wall Leaves larger solutes in bloodstream Reabsorption The result of osmotic pressure OP Blood colloid osmotic pressure BCOP Also referred to as 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 Interplay between Filtration and Reabsorption 1 Ensures that plasma and interstitial fluid are in constant communication and mutual exchange 2 Accelerates distribution of 3 Assists in the transport of Nutrients hormones and dissolved gases throughout tissues Insoluble lipids and tissue proteins that cannot enter bloodstream by crossing capillary walls 4 Has a flushing action that carries bacterial toxins and other chemical stimuli to Lymphatic tissues and organs responsible for providing immunity to disease Interplay between Filtration and Reabsorption Net hydrostatic pressure dP between inside outside of capillry Forces water out of solution out of capillary into interstitial fluid Net osmotic pressure Forces water into solution from outside capillary to inside Both control filtration and reabsorption through capillaries Factors that Contribute to Net Hydrostatic Pressure 1 Capillary hydrostatic pressure CHP 2 Interstitial fluid hydrostatic pressure IHP Net capillary hydrostatic pressure tends to push water and solutes 1 Blood colloid osmotic pressure BCOP 2 Interstitial fluid colloid osmotic pressure ICOP Out of capillaries Into interstitial fluid Net Capillary Colloid Osmotic Pressure Is the difference between Pulls water and solutes Into a capillary From interstitial fluid Net Filtration Pressure NFP The difference between Net hydrostatic pressure Net osmotic pressure NFP Net hydrostatic pressure Net osmotic pressure NFP CHP IHP BCOP ICOP Usually in normal conditions the IHP ICOP are equal to each other so the equation can be simplified to NFP CHP BCOP simplify for normal conditions Capillary Exchange At arterial end of capillary NFP 0 filtration occurs Fluid moves out of capillary Into interstitial fluid Fluid moves into capillary At venous end of capillary NFP 0 reabsorption occurs Out of interstitial fluid Transition point between filtration and reabsorption Is closer to venous end than arterial end Capillaries filter more than they reabsorb Excess fluid enters lymphatic vessels Capillary Dynamics Hemorrhaging Dehydration Reduces CHP and NFP Increases reabsorption of interstitial fluid recall of fluids Increases BCOP blood vol dec BCOP inc less fluid in blood but same amount of solute Accelerates reabsorption 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 Carries O2 and nutrients to tissues and organs
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