Connective tissue arterial wall

Fig. 55. An artery in a vitamin C-deficient guinea pig, showing vacuolation of both endothelium and connective tissue of wall (near site of bone injury).

Due to the significant amount of elastic connective tissue and smooth muscle in their walls, arteries tend to recoil rather powerfully, which keeps the pressure within them high. In contrast, veins contain less elastic connective tissue and smooth muscle so the tendency to recoil is significantly less and the pressure remains low. 

Atherosclerosis is a wide-spread pathology, manifested chiefly by the deposition of cholesterol in arterial walls, which results in the formation of lipid plaques (atheromas). Lipid plaques are specific foreign bodies around which the connective tissue develops abnormally (this process is called sclerosis). This leads to the cal-cification of the impaired site of a blood vessel. The blood vessels become inelastic and compact, the blood supply through the vessels is impeded, and the plaques may develop into thrombi. 

Function and location of elastin Cause of Marfan syn drome Elastin is a connective tissue protein with rubber-like properties. Elastic fibers composed of elastin and glycoprotein microfibrils, such as fibrillin, are found in the lungs, the walls of large arteries, and elastic ligaments. [Note Mutations in the fibrillin gene are responsible for Marfan syndrome]... 

The test of BASYC tubes as small-vessel prosthesis for other artificial pipehnes (arteries, veins, lymph, and urine leading vessels) is under progress. Initial results of the implantation of BASYC material into jugular veins of 10 white rats showed no complications such as wall-proliferation, stenosis or thrombosis. A normal blood flow through the interposition as well as the formation of connective tissue around it were detectable 4 and 12 weeks, respectively, after the operation [124]. 

Blood vessels include capillaries, arterioles, arteries, and veins. Each of these structures is composed of three layers the intima, media, and adventitia (Figure 3.12). For example, in elastic arteries the wall consists of an intimal layer containing endothelial cells and connective tissue a media containing smooth muscle cells, collagen, and elastic fibers and an adventitia containing collagen fibers, nerves, and blood vessels. In cross-section,... 

During inflammation, degranulation of immune cells releases serine proteases that pass through and bind to the capillary wall. Increased levels of Bik suppress these immune cell proteases and protect the extracellular matrix in arterial walls and connective tissue [4]. Bik inhibits phagocytic destruction of cells. Bik has been shown to inhibit elastases, granzymes A and K [4, 57], Mast cell tryptases (J3- and a-tetrameric forms with a molecular weight of 134 kDa) are resistant to aprotinin [58]. Lymphocytes serine esterase TL2 is not inhibited by Bik [59]. 

Hyaluronic acid consists of repeating disaccharides of /3-D-glucopyranosyluronic acid-(l— 3)-iV-acetyl-D-galactosamine linked p- l 4) to the next disaccharide. This proteoglycan can have between 500 and 50,000 residues per chain [92]. Hyuronic acid is found widely distributed in mammalian cells and tissues, where it is found in synovial fluid that lubricates the joints, in the vitreous humor of the eye, and in connective tissue, such as the umbilical cord, the dermis, and the arterial wall. It also occurs as a capsular polysaccharide around certain bacteria, such as pathogenic streptococci [92]. 

Peniciiiamine Taic and other siiicates Tetradecyisuifate Na Vascular lesion in connective tissue matrix of arterial wall, glomerular immune complex deposits, inhibits synthesis of vascular connective tissue Pulmonary arteriolar thrombosis, emboli Sclerosis of veins Glomerulonephritis... 

The normal artery wall is composed of three layers intima, media, and adventita (Figure 20-10). On the luminal side, the intima contains a single layer of endothelial cells. These cells permit passage of water and other substances from blood into tissue cells. On the peripheral side, the intimal layer is surrounded by a fenestrated sheet of elastic fibers (the internal elastic lamina). The middle portion of the intimal layer contains various extracellular components of connective tissue matrix and fibers and occasional smooth cells, depending on the type of artery, and the age and sex of the subject. 

Biopsy specimens of PAH include constrictive lesions and complex lesions. Constrictive lesions comprise medial hypertrophy and intimal thickening. Medial hypertrophy is defined as the increase in both number and cross-sectional area of the SM cells lining the walls of the pre- and intra-acinar pulmonary arteries intimal thickening implies an increased number of fibroblasts in the thin layer between a SM cell and lamina propria of the blood vessel. These changes can be seen in both IPAH and pulmonary venous hypertension. In contrast, complex lesions are considered pathognomonic for PAH. The complex or plexiform lesion consists of focal proliferation of endothelial channels consisting of fibroblasts, SM cells, and connective tissue matrix. These lesions disrupt vascular vessel wall and serve as a nidus for in situ thrombosis. 

Proteoglycans are found in interstitial connective tissues, for example, the synovial fluid of joints, the vitreous humor of the eye, arterial walls, bone, cartilage, and cornea. They are major components of the ECM in these tissues. The proteoglycans interact with a variety of proteins in the matrix, such as collagen and elastin, fibronectin (which is involved in cell adhesion and migration), and laminin. 

Cardiovascular disease is the primary cause of death, in both the United States and Europe, with arteriosclerosis being the most common form. The process of arteriosclerosis is considered to consist largely of the accumulation of lipids within the artery wall [1]. By surgical therapy new pathways (conduits) are being constructed, connecting the aorta or other major arteries and distal segments of arteries (e.g., coronary arteries) with vessels beyond the stenosis or obstructing lesions. By this means, blood supply to ischemic tissues can be re-established... 

Cells in an arterial wall have multiple attachments to surrounding connective tissue. 

The arteries are composed of elastin and collagen fibers and smooth muscles in a complex circumferential organization with a variable helix. Accordingly, the arteries are compliant vessels, and their wall stiffness increases with deformation, as in all other connective tissues. Because of their ability to expand as transmural pressure increases, blood vessels may function to store blood volume under pressure. In this sense, Aey fimction as capacitance elements, similar to storage tanks. The linear relationship between the volume V and the pressure defines the capacitance of the storage element, or the vascular capacitance ... 

Atherosclerotic plaques The protruding masses that form on the inner walls of arteries in atherosclerotic disease. A mature plaque consists partly of lipid, mainly cholesterol esters, which may be free or contained in lipid-engorged macrophages called foam cells, and partly of an abnormal proliferation of smooth-muscle and connective-tissue cells. 

A characteristic feature of a gel is its elastic behavior the gel deforms by an imposed force and it relaxes to its original state after releasing the force. Elastin, a crosslinked polypeptide network takes care of the elasticity of human and animal connective tissues, such as skin, ligaments, and arterial walls. For a more extensive discussion on the rheological properties of gels, the reader is referred to Chapter 17. 

While it is difficult to obliterate multiple arteriovenous connections via the feeding arteries, this can be easily achieved by packing the lumen of the single venous channel of the lesion. Although this might induce transient pressure elevation inside the nidus, rupture and bleeding does not occur, as the nidus is located within the dura and is surrounded by thick walls, reinforced by connective tissue proliferation (Houdart et al. 1993). In contrast to brain AVMs, venous occlusion is feasible... 

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