Cardiovascular System Pt. 2 E&P2 PDF

Capillaries - Capillaries: arterial branch and form smaller and less muscular vessels called metarterioles - Materioles: end in microscopically small blood vessels called capillaries that contain 6% of total blood vol. (smaller component where gas exchange occurs) - Capillary wall: consists of singl...

Capillaries - Capillaries: arterial branch and form smaller and less muscular vessels called metarterioles - Materioles: end in microscopically small blood vessels called capillaries that contain 6% of total blood vol. (smaller component where gas exchange occurs) - Capillary wall: consists of single layer of rolled up endothelial cells - Some capillaries are so narrow that only 1 blood cell at a time cane squeeze through Capillaries: Blood Flow - Precapillary sphincter: has ring of smooth muscle that encircles capillary at its origin and controls its diameter - Sphincter constriction and relaxation provide means for blood flow regulation w/in specific tissue to meet metabolic requirements - 2 factor trigger precapillary sphincter relaxation to open more capillaries: - 1. Driving force of: - Increase local BP + - Intrinsic neural control - 2. Local metabolites produced in exercise Capillary Blood Flow at Rest and During Exercise - During activity/exercise → open precapillary sphincters and can get most nutrients and oxygen to fuel Venous System Components - Capillaries feed deoxygenated blood into small veins or venules - Veins in lower body empty into inferior vena cava = bodies largest vein - Inferior vena cava returns blood to → right atrium from: - Abdomen - Pelvis - Lower extremities - Veins in upper body empty into superior vena cava and joint the inferior vena cava at the heart (mixed venous blood) - Superior vena cava returns blood to right atrium from: - Head - Neck - Shoulder - Thorax - Abdominal wall Venous Return - Low capacitance = low capacity to store blood w/ not much flexibility or malleability - High capacitance = high capacity to store blood w/ lots of flexibility - Venous side: low pressure and lots of blood volume = high capacitance - Any movement → cardiac output and venous return occurs Valves in Veins - Valves functions: are one way - Prevent backflow of blood (a) - Do NOT hinder normal 1-way flow (b) - Blood moves through veins by action of nearby active muscle (c) - Contraction of smooth muscle (d) Blood Flow and BP in Systemic Circulation at REST - BP w/in each portion of arterial system relates to total area (resistance) in that section - Arterioles to capillaries → vascular area dips Various Veins - Varicose vein: open damage valve that allow blood flow through BUT also allows blood flow to push back→ leads to damaged area b/w 2 valves - Causes veins to reshape - Change in flow → vein easily rechange BP Response to Resistance Exercise - During exercise → systolic BP and diastolic BP increase - Aerobic: not much change in diastolic but change in systolic - Anaerobic/resistance: diastolic and systolic increase - Upper body: lower BP than lower body - Load of stimulus and size of musculature active expenditure matters and changes BP response - Imparts arterial circuit due to tension being created in musculature under that load - Don’t see in aerobic exercise BP Response to Steady-Rate Physical Activity - During rhythmic muscle activity: vasodilation in active muscles decrease TPR to increase blood flow through peripheral vasculature - Alternate muscle contraction/relax. → propels blood through vascular circuit back to the heart - Increase blood flow during steady-rate exercise rapidly increases SBP during first few minutes - SBP often decreases as steady-rate exercise continues b/c: - Arterioles in active muscles continue to dilate, further decrease peripheral resistance to blood flow DBP generally remains unchanged throughout exercise BP Response to Graded Exercise (VO2 max) BP Response to Upper Body PA/Exercise - At given percentage of VO2max in each exercise mode: arm-based exercise increase SBP and DBP vs. leg exercise - Smaller arm muscle mass and vasculature offer greater resistance to blood flow than activation of larger leg mass and blood supply - Indvs. w/ cardiovascular dysfunction should rhythmically exercise relatively large muscle groups vs. limited muscle mass exercises and at a lower intensity BP Response in Exercise Recovery - Massive decrease in systolic and slight decrease/stays the same in diastolic → even gets to below level prior to exercising