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Stack #14564
ch21
Question | Answer |
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how many distinct layers do the walls of arteries and veins have? | three distinct layers. 1. Tunica Intima, turnica media, turnica externa |
tunica intima | innermost layer of a blood vessel |
internal elastic membrane | in arteries, tunica intima contains this thick layer of elastic fibers |
tunica media | the middle layer of the vessel walls |
external membrane | thin band of elastic fibers that separates the tunica externa |
tunica externa | outermost layer of blood vesseland forms a connective tissue sheath |
vasoconstriction | when stimulated, arterial smooth muscles contract and thereby constrict the artery |
vasodilation | relaxation of these smooth muscles increases the diameter of lumen. |
what 3 things do vasoconstriction and vasodilation affect? | 1) the afterload of the heart 2) peripheral blood pressure 3) capillary blood flow |
elastic arteries | conducting arteries; large vessels that transport large volumes of blood away from the heart. Examples of elastic arteries are: pulmonary trunk, aorta, as well as their major arterial branches |
muscular arteries | medium-sized arteries or distribution arteries. they distribute blood to the body's skeletal muscle and internal organs. Have thick tunica media and smooth muscle cells, as opposed to elastic tunica media |
Arterioles | smaller than muscular arteries. in the tunica media, smooth muscle cells donot complete a whole layer. |
arteriosclerosis | thickening and toughening of the arterial walls. |
what are the 2 major forms of arteriosclerosis? | 1) Focal calcification 2) Atherosclerosis |
focal calcification | the gradual degeneration of smooth muscle in the tunica media and deposit of calcium salts |
atherosclerosis | associated with damage to the endothelial lining and the formation of lipid deposits in the tunica media |
plaque | fatty mass of tissue that projects into the lumen of the vessel |
resistance (R) | force opposing blood flow |
resistance vessels | arterioles that force opposing blood flow |
aneurysm | when local arterial pressure exceeds the capacity of the elastic componets of the tunics |
continuous capillary | the endothelium is a complete lining. It supplies most regions of the body. Located on every tissue except epithelia and cartilidge |
fenestrated capillaries | capillaries that contain "windows", or pores that span the endothelial lining. The pores permit the rapid exchange of water and solutes as large as small peptides between plasma and interstitial fluid |
sinusoids | resemble fenestrated capillaries that are flattened and irregular. In contrast to fenestrated capillaries, sinusoids commonly have gaps between adjacent endothelial cells, and the basal lamina is either thinner or absent. Blood moves thru slowly |
Capillary bed | an interconnected network of capillaries since capillaries do not function as individual units |
capillary plexus | same as capillary bed |
precapillary sphincter | a band of smooth muscle that guards the entrance to the capillary |
metarteriole | the wall in the initial part of a passageway that have smooth muscles capable of changing its diameter |
thoroughfare channel | the rest of the passageway that resembles a typical capillary in structure |
collaterals | multiple arteries that bring blood to the capillary bed |
arterial anastomosis | fusion of 2 collateral arteries that supply a capillary bed |
arteriovenous anastomoses | direct connections between arterioles and venules. |
vasomotion | the cycling of contraction and relaxation of smooth muscles that change blood flow thru capillary beds |
veins | collect blood from all tissues and organs and return it to the heart |
venules | collect blood from capillary beds, are the smallest venous vessels |
medium sized veins | range from 2mm to 9mm in internal diameter, the tunica media is thin and contains few smooth muscle cells |
large veins | includes the superior and inferior vena cavae and all their tributaries within the abdominopelvic and thoracic cavities |
valves | folds of tunica intima that project from the vessel wall and point in the direction of blood flow. Thepermit blood flow in one direction |
capacitance vessels | another term for veins because they expand easily |
venoconstriction | reduces the amount of blood within the venous system and increases the volume within the arterial system and capillaries |
venous reserve | 20% of total blood volume. It is the amt of blood that can be shifted from veins in the liver, skin, and lungs to the gereral circulation |
hydrostatic pressure (HP) | a fluid pressure that is conducted in all directions. pushes a liquid in a higher pressure to a lower pressure |
Capillary hydrostatic pressure (CHP) | the pressure within capillary beds |
venous pressure | pressure within the venous system |
total peripheral resistance | the resistance of the entire CV. |
peripheral resistance | resistance of the arterial system |
vascular resistance | resistance of the blood vessels, is the largest component of peripheral resistance. The amount of friction depends on the length and diameter of the vessel |
turbulance | phenomenon that increases resistance and slows blood flow as a result of high flow rates, irregular surfaces, and sudden changes in vessel diameter |
systolic pressure | the peak blood pressure measured during ventricular systole |
diastolic pressure | the minimum blood pressure at the end of the ventriculardiastole |
pulse pressure | the difference between the systolic and diastolic pressures |
mean arterial pressure (MAP) | calculated by adding one-third of the pulse pressure to diastolic pressure |
elastic rebound | helps maintain blood flow along the arterial network while the left ventricle is in diastole |
hypertension | abnormally high blood pressure |
hypotension | abnormally low blood pressure |
Capillary hydrostatic pressure (CHP) | blood pressure in a capillary |
osmotic pressure | indication of cosmotic water movement. The pressure that must be applied to prevent osmotic pressure movement across a membrane |
net filtration (NFP) | the difference between the net hydrostatic pressure and the net osmotic pressure |
edema | abnormal accumulation of interstitial fluid |
fainting | temporary loss of consciousness |