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hemodynamics th emeans by which blood flow is altered and distributed and by which BP is regulated angiogenesis the growth of new blood vessels blood vessels these form a closed system of tubes that carry blood away from the heart arteries carry blood from the heart to the tissues arterioles these are small arteries that connect to capillaries` capillaries these are sites of substance exchange between the blood and body tissue venules these connect capillaries to larger veins veins these convey blood from the tissues back to the heart vaso vasorum these are small BV that supply blood to the cells of the arterial and veinal walls 3 how many layers do the walls of blood vessels have? tunica interna innermost layer of BV composed of a layer of endothelium endothelium this helps prevent blood clotting by providing a smooth surface and secreting biochemicals that inhibit platelet aggregation vasodilators, vasoconstrictors endothelium regulates blood flow by secreting _________ and __________. Tunica media the middle, thickest tunic. makes up bulk of arterial wall smooth muscle, CT two types of muscle tissue BV are composed of autonomic NS, hormones what regulates the Tunica Media Vasoconstriction reduction in the lumen as the smooth muscle contracts vasodilation increase in the lumen as the smooth muscle relaxes tunica externa also called the adventitia tunica externa the outer layer mainly consisting of fibrous CT (thickest layer in veins) protects, reinforces vessel the functions of the tunica externa elasticity and contractility the functional properties of the arteries. vasospasm injury to artery or arteriols cause muscle contraction to reduce blood loss, also called ______________. elastic arteries large arteries with more elastic fivers and less smooth muscle pressure reservoir the function of the elastic arteries muscular arteries these deliver blood to specific body organs and account for most of the named arteries arterioles deliver blood to capillaries arterioles function in regulating blood flow from arteries into capillaries and in altering arterial blood pressure increases, decreases arteriole dilation ___________ blood flow to capillaries and _______ pressure in the arteries decreases, increases arteriole constriction __________blood flow to the capillaries and _________ pressure in the arteries epithelia, cornea, lens, cartilage places that lack capillaries metabolism capillary density within tissues varies directly with the tissues' rate of ___________ continuous capillaries intercellular clefts are gaps between neighboring cells fenestrated capillaries plasma membranes have many holes sinusoidal capillaries very large fenestrations and incomplete basement membrane continuous, fenestrated, sinusoidal three structurally different types of capillaries venules small veins collecting blood from capillaries veins return blood to the heart parallel veins run _______to arteries valves veins have these to prevent the back flow of blood positive feedback an example of this is the increase in venous constriction in response to a drop in arterial pressure 64 percentage of blood volume at rest that reside in the systemic veins and venules venoconstriction increased muscular activity produces this hemorrhage this causes venoconstriction to help maintain blood pressure 13 percentage of blood volume in arteries and arterioles diffusion most important method of moving materials in and out of a capillary oxygen, carbon dioxide, glucose, amino acids, hormones List different substances that diffuse through the capillaries blood brain barrier doesnt allow diffusion of water-soluble materials transcytosis passage of material across endothelium in tiny vessicles by endocytosis and exocytosis insulin an example of a substance that is transported via transcytosis is ___________.