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The Beneficial Effect of Omega-3 PUFA and L-Arginine on Endothelial Nitric Oxide (NO) Bioavailability
Published in Robert Fried, Richard M. Carlton, Flaxseed, 2023
Robert Fried, Richard M. Carlton
Arterial blood vessels have three major structures: The innermost layer, the tunica intima (also called tunica interna), is simple squamous epithelium surrounded by a connective tissue basement membrane with elastic fibers. The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer. It not only provides support for the vessel but also changes vessel diameter to regulate blood flow and blood pressure. The outermost layer, which attaches the vessel to the surrounding tissue, is the tunica externa or tunica adventitia. This layer is connective tissue with varying amounts of elastic and collagenous fibers. The connective tissue in this layer is quite dense where it is adjacent to the tunica media, but it changes to loose connective tissue near the periphery of the vessel.
Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
The tunica media is the middle layer of the vessel wall. It is made up of both smooth muscle and connective tissue and shows the greatest variation among the blood vessels of the circulatory system. When the smooth muscle contracts in vasoconstriction, there is a decrease in radius, an increase in resistance, and a resulting decrease in blood flow. The external elastic lamina forms the outer portion of the tunica media. The tunica externa (or adventitia) is made up of collagen and elastin fibers, which contribute to the mechanical properties of the blood vessels. It also helps anchor the vessels to the surrounding tissue. In the larger vessels, there are small blood vessels (the vasa vasorum) that supply the outer layers of the blood vessel wall with oxygen and nutrients. A weakened area of the wall with less connective tissue reinforcement may result in a region of expansion (a “bulge”) known as an aneurysm. This could be a result of a genetic defect (such as Marfan’s syndrome) or a disease state such as atherosclerosis and syphilis. If the wall becomes further stretched, it may result in rupture. Surgery is often done to repair this and prevent further rupture. This will be discussed further in Chapter 6.
Cardiovascular System
Published in David Sturgeon, Introduction to Anatomy and Physiology for Healthcare Students, 2018
The average adult has approximately five litres of blood distributed throughout the cardiovascular system in a number of different vessels (Figure 7.1). There are three main types of blood vessel: arteries, veins and capillaries. Structurally, arteries and veins are very similar. Both have a fibrous outer layer or membrane called the tunica adventitia or tunica externa (from the Latin for ‘outer coat’). Beneath this is a layer of smooth muscle and elastic tissue called the tunica media (‘middle coat’). The inner lining (tunica intima) of both vessels consists of a single layer of simple squamous epithelial cells known as endothelium (Figure 7.2). The endothelium is in direct contact with the blood and provides an uninterrupted and non-thrombogenic surface (i.e. it discourages clotting). Although both arteries and veins are constructed from the same three layers of tissue there are a number of distinct anatomical differences between them. Firstly, arteries always travel away from the heart (‘A’ for ‘artery’ and ‘away’) and veins travel towards it. Secondly, arterial walls are thicker than veins since they contain more smooth muscle and elastic tissue in the tunica media. Smooth muscle is necessary for vasoconstriction and vasodilation in both vessels but the quantity reflects the different pressures exerted by the blood against artery and vein walls (see Chapter 8). Finally, since veins return blood to the heart (at low pressure) many, particularly those of the lower limb, contain valves in order to prevent backflow.
Four-day pulse of sodium cromoglycate modulates pulmonary vessel wall remodeling during 21-day hypoxia in rats
Published in Experimental Lung Research, 2018
Tomáš Novotný, Jiří Uhlík, Luděk Vajner
H21 – Morphological findings in lung arteries of rats exposed to 21-day normobaric hypoxia were in logical continuity with our findings in 4-day hypoxia experiment,[1] when first morphological remodeling changes of pulmonary arteries were induced and noticeably detectable.[25] After 3 weeks of hypoxia, we observed fully developed remodeling of peripheral (resistance) arteries in accordance to references.[26,27] All morphological aspects of these processes are visible, and gene expression is supposed to be changed in accordance to hypoxia exposure.[28] Hypoxic remodeling of muscular peripheral arteries led to trilaminar transformation of tunica adventitia. We presume this change to edema of tunica adventitia, which can be caused by specific hypoxic constrictive lesion of muscular pulmonary arteries.[29] This arrangement is different from large conduit arteries, which preserve bilaminar physiological arrangement of tunica adventitia in spite of hypoxic remodeling. Such an organization of tunica adventitia is referred to as tunica adventitia and tunica externa.[30]
Systemic effects after intravitreal injection of bevacizumab in new born rabbit eyes
Published in Cutaneous and Ocular Toxicology, 2018
Yih-Shiou Hwang, Chi-Hsien Liu, Yin-Cheng Huang, Chih-Shan Chen, Tun-Lu Chen, Nan-Kai Wang, Yen-Po Chen, Kwan-Jen Chen, Chi-Chun Lai, Wei-Chi Wu
The histology of the respiratory system (Figure 1) showed normal trachea, bronchi, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli in all groups of animals. The histology of the heart (Figure 2) showed normal epicardium, myocardium, and endocardium in all groups of animals. The histology of the aorta showed normal tunica externa, tunica media, and tunica intima in all groups of animals. The histology of the digestive organs (Figure 3) showed normal esophagus, stomach, small intestine, and colon. The mucosa, submucosa, muscularis externa, and adventitia of the gastrointestinal systems showed no differences in any group of animals. The histology of the liver (Figure 4) revealed normal hepatocytes, central vein, and portal canal, and there was no infiltration of inflammatory cells in any group of animals. The gallbladder showed normal tunica mucosa, tunica submucosa, tunica muscularis, and tunica serosa in all groups of animals. The histology of the kidney (Figure 5) showed normal glomeruli and tubular structures in all groups of animals. Ureters and urinary bladders also showed normal histology in all groups of animals. Testis histology did not show abnormalities in tunica albuginea, seminiferous tubules, ductuli efferentes, epididymis, or vas deferens.