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62 Cards in this Set
- Front
- Back
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Role of blood vessels |
Move blood to and from lungs and out of heart Provide oxygen and nutrients and remove wastes |
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Order of vessels |
Left ventricle Arteries Arterioles Capillaries Venues Veins Right atrium |
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Properties of Blood vessels |
requires specializations depending on the location of vessels requires ability to self regulate and respond to ANS Arteries and veins as conduits; cap are workhouses RESILIENT FLEXIBLE |
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Blood vessel structure |
Tunica Intima Tunica media Tunica externa |
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Tunica intima |
innermost layer endothelial layer with connective tissue (basal lamina) -internal elastic membrane IN ARTERIES |
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Tunica media |
middle; has concentric layers of smooth muscle cells with connective tissue supporting; thickest layers for many ARTERIES -separated from external by external elastic membrane |
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Tunica externa |
connective tissue sheath; joins with surrounding connective tissue to stabilize BV -THICKEST LAYER FOR MANY VEINS |
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Vasa vasorum |
small arteries and veins supply the tunica media and externa of larger vessels |
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Arteries need: |
elasticity- to passively absorb pressure changes contractility- to actively change diameter/ respond to sympathetic stimulation -vasoconstriction - decrease diameter -vasodilation - increase diameter |
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Elastic arteries |
CONDUCTING ARTERIES large vessels leading away from heart diameter up to 2.5 cm -elasticity required to dampen the pressure changes that alternating cycles of systole and diastole elastic recoil |
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Muscular arteries |
DISTRIBUTION ARTERIES (medium sized) responsible for supplying muscles and organs with blood; MOST ARTERIES ARE LIKE THIS -diameter of .4 -.5 mm -pressure points to control severe bleeding (also pulse points) |
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Arterioles |
RESISTANCE VESSELS (smaller diameter) -respond to local stimulation so can vasodilator in response to low O2 to increase blood flow and sympathetic stim to vasoconstrictor -controls blood flow thru cap beds |
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Metartioles |
short vessels that link arterioles to venues and lead into cap -has vascular smooth muscle cells form pre capillary sphincters around entrance to cap -constriction of these reduces blood flow -relaxation allows flow |
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Vasomotion |
cyclical contraction and relaxation of vascular smooth muscle helps to divert blood flow across entire cap bed * auto regulation increases blood flow to more active tissues |
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How much blood is in the cap at any given time? |
25% capillaries with blood in them |
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Capillaries |
-Composed of endothelial cell layer and basement membrane (only tunica intima) -thin walls of cap and slow flow allows for bi-directional exchange of products |
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Continuous |
found in all tissues except epithelia and cartilage -small solutes, water, lipid soluble (not blood cell or plasma port) -may be modified with tight junctions to form blood brain barrier |
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Fenestrated |
has pores spanning the endothelial layer -also allows small peptides, hormones out -choroid plexus, endocrine organs, kidney |
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Sinusoid |
smilier to fenestrated, but gaps between endothelial cells and missing or incomplete basal lamina, so even plasma proteins and RBCs can pass; liver, bone marrow, spleen |
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Shortcuts |
Collateral arteries - arterial anastomoses Thoroughfare channel Arteriovenous anastomoses |
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Collateral arteries - arterial anastomoses |
arteries that fuse before entering arterioles |
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Thoroughfare channel |
met arteriole that continues through capillary bed from arteriole to venue |
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Arteriovenous anastomoses |
direct connection between arteriole and venule to completely bypass the cap bed |
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Veins |
thinner walls because lower pressure (closer to left vent. higher pressure) |
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Venules |
has valves (folds of tunica) resists back flow keeps blood flow unidirectional -improves venous return -venous pooling |
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Medium sized veins |
also has valves |
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Distribution of blood |
more blood systemic (84%) than pulmonary (about 16%) -heart, arteries capillaries - 30-35% blood -venous system - 65-70% blood (veins as capacitance vessels |
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What shunts blood from veins to arteries to keep arterial blood level near normal despite large losses of blood; triggered by symp nervous system? |
venoconstriction |
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Venous reserve |
(20% total blood volume) |
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Aneurysm |
bulge in weakened wall of BV where elastic and connective tissue elements can no longer support the pressure; may rupture, causing a stroke in the brain or excessive bleeding |
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Arteriosclerosis |
thickening and toughening of artery walls -in coronary arteries, causes coronary artery disease -can be either calcifications |
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Atherosclerosis |
which is when lipid deposits in tunica media that damage the endothelial lining (high cholesterol) |
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Role of cardiovascular system |
regulate blood flow increase flow to more active regions -local regulation -systemic extrinsic make sure exchange of nutrients and wastes can occur |
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What is blood flow usually equal to? |
Cardiac Output |
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What is flow determined by? |
change of pressure / resistance |
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Pressure |
Hydrostatic pressure Circulatory pressure |
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Hydrostatic pressure |
pressure from liquid inside vessels pushing OUT against walls -flow rate is directly proportional to pressure gradient -pressure gradient is highest at the pump (heart), lowest at the right atrium |
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Circulatory pressure |
pressure gradient throughout circulatory system -BP -CHP Venous Pressure |
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Blood Pressure |
arterial pressure (100-35 mmHg near cap bed) |
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Capillary Hydrostatic Pressure |
pressure within the cap beds (35-18 mmHg) |
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Venous Pressure |
pressure within the venous system (gradient from the venues to right atrium) (18-2 mmHg) |
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Total peripheral resistance |
resistance of entire cardiovascular system; opposes the flow of blood
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Peripheral resistance |
resistance of the arterial system f= delta P/R |
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Vascular resistance |
friction -vessel length (increase length, increase resistance) -vessel diameter (increase diameter, decrease resistance) -viscosity (increase viscosity, increase resistance) -turbulence (increase turbulence, increase resistance) |
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Laminar vs Turbulent flow |
smooth vs disrupted |
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Elastic rebound in arterial pressure |
forces most of it forward towards capillaries so keeps blood moving during diastole |
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Importance of capillary exchange |
provides nutrients and O2 removes wastes and CO2 transfer of fluids to lymphatics |
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Capillary exchange affected by: |
Diffusion Filtration Reabsorption |
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Diffusion |
possible routes - thru cell (lipid sol) between endothelial cells, thru pores, thru channels |
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Filtration |
when water (carrying small solutes) is forced out of cap; occurs due to CHP |
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Reabsorption |
When water (and suspended small solutes) are "reclaimed" back into cap; occurs due to osmotic pressure -BCOP |
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CHP |
35 mmHg at arterial end 18 mmHg at venous end |
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Hydrostatic pressure of interstitial fluid |
0 |
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BCOP |
25 mmHg the whole way |
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interstitial fluid colloid osmotic pressure |
0 |
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Net filtration pressure |
NFP = net hydrostatic pressure - net colloid osmotic pressure NFP = (CHP - IHP) - (BCOP - ICOP) |
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NFP at arterial end = |
10 mmHg (causes fluid to move out) when positive |
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NFP at venous end = |
-7 mmHg (causes fluid to move in) when negative |
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How much filtered blood is moved back in? |
85% and 15% goes into lymphatic vessels (eventually returns to venous system) |
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Venous pressure and Venous return |
very low pressure, but also very low resistance venous return in legs must overcome gravity MUSCULAR COMPRESSION RESPIRATORY PUMP |
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Muscular compression |
skeletal muscle contractions |
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Respiratory pump |
inhaling decreases pressure in thoracic cavity which pulls air into lungs and blood into inferior vena cava and right atrium; THEN exhale, increases pressure in thoracic cavity, causes blood to be forced into the right atrium; keeps blood moving along |
