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Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The blood vessel wall is made up of three layers: the tunica intima, the tunica media, and the tunica externa (Figure 1.7). The innermost layer, the tunica intima, is made up of a basement membrane and endothelium, which is in contact with the blood as the blood moves through the blood vessel lumen. The endothelial cells secrete chemicals such as endothelin and nitric oxide, which can trigger a local vasoconstriction or vasodilation. The endothelium also provides a smooth surface that minimizes the friction at the wall. The basement membrane and the internal elastic lamina make up the rest of the tunica intima. The network of collagen fibers within the basement membrane and the layers of elastic fibers within the lamina provide tensile strength to the wall while also allowing for stretching and recoiling.
Vessel Wall Imaging
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
The size of the mouse arterial wall thickness is <50 mm. The arterial wall of small animals such as rats and mice consists of three tunics (from inside to outside): the tunica intima, the tunica media, and the tunica adventitia. Although the main anatomic and histologic structure of the vasculature in humans and mice are similar, differences such as thinner walls in mouse arteries and the prominent presence of cardiomyocytes around the pulmonary veins of mice have been noticed (Laflamme et al. 2012). Moreover, in a mice coronary artery study, the authors reported that the microstructure of the three arterial layers slightly differs between species. In the coronary arteries of mice, the tunica intima consists of an endothelial layer, an inconspicuous subendothelial connective tissue, and an undulating internal elastic lamina. The tunica media consists of circularly arranged smooth-muscle fibers, and the tunica adventitia consists of collagen and elastic fibers (Khan et al. 2006). Of note, histologically altered arterial wall presenting different biomechanical and microstructural properties can be achieved using various transgenic mice models such as the n fibulin-5 null mice, enabling the investigation of a variety of cardiovascular diseases (Stone et al. 2004; Wan et al. 2010; Wan and Gleason 2013).
Nanofibers: Production Techniques and Applications
Published in Raj K. Keservani, Anil K. Sharma, Rajesh K. Kesharwani, Drug Delivery Approaches and Nanosystems, 2017
Hemant K. S. Yadav, Nour A. H. Alhalabi, Ghufran A. R. Alsalloum
The function of blood vessels in the body is to carry and transport blood from and to the heart. Depending on their location and function, blood vessels have various sizes, mechanical and biochemical properties, cellular content, and structural organization. Tissue of blood vessels and the heart are delicate and complex in structure, and any damage to them can lead to serious health problems. The vessel wall consists of three layers, tunica intima, tunica media, and tunica adventitia. The innermost layer is the tunica intima, with non-thrombogenic monolayer endothelial cells. Separated from the tunica intima, by an internal elastic lamina, is the tunica media, which is composed of concentrically organized smooth muscle cells. The tunica adventitia is the outermost layer and is composed of collagenous extracellular matrix and fibroblast cells. Generally, the ECM surrounding the vascular cells contains collagen (type 1 and type 3) elastin, proteoglycans and glycoproteins (Kanani and Bahrami, 2010). The ECM of cardiac tissue has cells in fiber-like bundles, which allows mechanical coupling of adjacent fibrils.
On the importance of tunica intima in the aging aorta: a three-layered in silico model for computing wall stresses in abdominal aortic aneurysms
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Mario de Lucio, Marcos Fernández García, Jacobo Díaz García, Luis Esteban Romera Rodríguez, Francisco Álvarez Marcos
The obtained results show an early exponential stiffening of tunica intima that makes it definitely load-bearing when it becomes thickened because of intimal hyperplasia. Intimal hyperplasia may be caused by two factors. The first one is the collagenization; The diffuse thickening of the innermost layer of the abdominal aorta has been associated by many studies with collagenization of the elastic and hyper-plastic layers, which increases the dispersion in the families of collagen fibers and stiffens up the intimal layer. The second factor could be related to the proliferation of smooth muscle cells between the endothelium and the internal elastic lamina. In any case, the intimal layer shows the highest percentages of stress absorption.