뒤로Blood Vessels - Anatomy & Physiology
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Blood vessels are tube-like structures forming a circulatory system to transport blood throughout the body.
Angiogenesis is the formation of new blood vessels.
Blood vessels can dilate, constrict, pulsate, proliferate (angiogenesis), allow exchange with surroundings, have diverse wall structures, and can self-repair, unlike rigid pipes.
Arteries, arterioles, capillaries, venules, and veins.
Capillaries wrap around alveoli to facilitate gas exchange.
Blood vessels typically have three tunics: tunica intima, tunica media, and tunica externa.
Endothelium (simple squamous epithelium), subendothelium (basement membrane and loose connective tissue), and internal elastic lamina in larger arteries.
The tunica media is the middle layer, mostly smooth muscle and elastic fibers, responsible for vasoconstriction and vasodilation to regulate blood flow and pressure.
Composed mostly of collagen fibers and vasa vasorum; it protects, reinforces, and anchors the blood vessel to surrounding tissues.
Arteries have thicker tunica media with more elastic fibers and smaller lumens; veins have thinner walls and larger lumens.
Elastic arteries (largest, near heart), muscular arteries (medium-sized, more smooth muscle), and arterioles (smallest, regulate blood flow into capillaries).
They stretch to hold blood from heart contraction and recoil during diastole to keep blood flowing.
Capillaries are the smallest blood vessels facilitating exchange of nutrients, gases, and wastes between blood and tissues.
Continuous capillaries, fenestrated capillaries, and sinusoid capillaries.
Most common, least permeable; found in muscle, nervous tissue, and connective tissue.
Endothelial cells contain fenestrations (small pores) allowing moderate permeability; found in kidneys, endocrine glands, and small intestines.
Capillaries with discontinuous endothelium and basement membrane, allowing passage of larger molecules and cells; found in liver, bone marrow, spleen.
An extensive network of numerous, branched, connected capillaries facilitating microcirculation.
Arterioles and precapillary sphincters regulate blood flow by vasoconstriction and vasodilation.
Anastomoses are convergence points of blood vessels providing alternate routes for blood flow, important during blockages.
Arterial anastomoses, venous anastomoses, and arteriovenous anastomoses.
Hemodynamics is the study of the physical principles of blood flow.
Blood flow is the volume of blood passing a point per time; blood pressure is the force blood exerts on vessel walls; resistance is friction opposing blood flow.
Blood flow is proportional to pressure difference and inversely proportional to resistance: \(F=\frac{\Delta P}{R}\)
Blood viscosity, vessel length, and vessel diameter (most easily altered).
Larger diameter decreases resistance, increasing blood flow; smaller diameter increases resistance, decreasing flow.
Arteries withstand higher blood pressure and regulate blood flow via thicker tunica media.