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Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
NO's role in skin temperature regulation centers on its effects on the smaller arteries. It signals the vascular smooth muscle in the tunica media to relax, resulting in vasodilation and increased blood flow. This potent vasodilator plays a major role in establishing both whole-body and regional “vascular tone.” So prominent are its vasodilating effects that NO is also known as endothelium-derived relaxing factor (EDRF). It is synthesized endogenously in essentially all tissues by nitric oxide synthase (NOS). Synthesis of NO requires the amino acid L-arginine, oxygen, and various cofactors, notably NADPH.
The patient with acute cardiovascular problems
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
The middle layer, the tunica media, is composed of smooth muscle and elastic fibrous tissue that is much thicker in arteries than in veins. This is to enable the arterial wall to expand and contract in response to the pressures generated by the contraction of the left ventricle and plays a crucial role in the control of blood pressure. The venous system is a much lower pressure system, and therefore the elastic muscular middle layer does not need to be as thick.
Structure of Initial and Collecting Lymphatic Vessels
Published in Waldemar L. Olszewski, Lymph Stasis: Pathophysiology, Diagnosis and Treatment, 2019
The adventitial layer consists of fibroblasts, collagenous fibers and fiber bundles, which are more or less loosely arranged and predominantly oriented parallel to the axis of the vessel. Nonmyelinated nerve fibers are also seen in this layer or close to it. The outer wall of collecting vessels is also supplied by a rich network of blood vessels (vasa vasorum). The blood vessels, however, do not enter the tunica media.
Targeting VCAM-1: a therapeutic opportunity for vascular damage
Published in Expert Opinion on Therapeutic Targets, 2023
Mayarling F Troncoso, Magda C Díaz-Vesga, Fernanda Sanhueza-Olivares, Jaime A Riquelme, Marioly Müller, Luis Garrido, Luigi Gabrielli, Mario Chiong, Ramon Corbalan, Pablo F Castro, Sergio Lavandero
The cardiovascular system includes the heart and blood vessels that pump and deliver blood throughout the body. Blood vessels are structured in three layers: the tunica intima, media, and adventitia. The tunica intima, or inner layer, comprises endothelial cells (EC) in contact with the blood. The tunica media or medial layer is formed mainly by vascular smooth muscle cells (VSMC) and the extracellular matrix, such as collagen and elastin, that regulates vascular tone and the integrity of vessels. In capillaries, the medial layer does not contain VSMC, but pericytes form a thin wall that facilitates the transport of blood components [3]. The adventitia layer, or outer layer, comprises fibroblasts, nerves, and small arteries (Vasa vasorum) that deliver nutrients to this layer [4].
Ultrastructural changes in resistance arterioles of normotensive and hypertensive premenopausal women with uterine fibroids
Published in Ultrastructural Pathology, 2023
LM Brewster, ID Perrotta, Z Jagernath, Z Taherzadeh, GA van Montfrans
The shape, orientation, and electron-density of smooth muscle cells in the tunica media varied across the vessel wall and between samples. Some smooth muscle cells were typically spindle-shaped, arranged in a circumferential or helical pattern around the vessel lumen with many appositional contacts among these myocytes, which showed a rather uniform intracellular electron-density due to the abundance and wide distribution of myofilaments. However, in normotensive and to a greater extent in hypertensive patients (both untreated and treated uncontrolled), there were areas in tunica media with a heterogeneous appearance of smooth muscle cells with a more rounded or cuboid shape, loss of intercellular appositional contact points, and various degrees of intracellular electron-lucency due to degenerative changes of the contractile apparatus.
Histopathological and ultrastructural study of carotid atherosclerotic plaques: a study of four cases
Published in Ultrastructural Pathology, 2021
Ru Yong-xin, Zhang Xue-bin, Dong Shu-xu, Zhang Yongqiang, Li Ying, Liu Jing, Gao Ying-dai, Shang Hong-Cai, Brian Eyden
The observation that all of the cells in the basal bands were positive for α-SMA is liable to allow the misinterpretation of a whole basal band as part of the tunica media stripped off together with an atherosclerotic plaque during the operation. Combining H&E, Congo red and α-SMA staining, every basal band included two parts with distinct patterns:- layers of d-VSMCs organized in elastin networks as normal tunica media at the bottom; and layers of irregular cells with common features of myofibroblasts and VSMCs inside the former part. The existence of d-VSMCs demonstrated that tunica media was affected during atherosclerosis.18,19 The layers of irregular myoid cells inside the affected tunica media confirmed that the cells were derived from MMSCs and constructed a pseudo-media.20,21 In case 2, the hemorrhage between the pseudo-media and the affected tunica media hinted at a reasonable mechanism of sporadic aortic aneurysms and dissections in cardiovascular diseases.22