Skin Microcirculation
John H. Barker, Gary L. Anderson, Michael D. Menger in Clinically Applied Microcirculation Research, 2019
The skin is the largest organ of the human body (in an adult, it measures approximately 3 mm thick × 2 m2 and weighs 2 kg) at any given time in resting, normo-thermic conditions contains 4.5% of the body’s circulating blood; by comparison, this same figure for skeletal muscle is 13.2%.58 When inflamed, it can increase blood flow many-fold and sustain this for repair. The skin microcirculation can be defined anatomically as arterioles, capillaries, venules, lymphatic capillaries, and arteriovenous anastomoses, or all vessels presenting a diameter of less than 300 µm. The larger vessels supplying the skin microcirculation can be said to arise from three separate sources: the direct cutaneous vessels, the musculocutaneous perforators, and the fasciocutaneous perforators.31 The larger vessels from these three systems spread through the subcutaneous tissue, giving branches to the supplying arterioles in the overlaying dermis (Figure 1).
The cardiovascular system
C. Simon Herrington in Muir's Textbook of Pathology, 2020
The microcirculation is the capillaries, the arterioles that supply them, and the venules that drain the blood from the capillary bed. A capillary consists of a single endothelial cell encircling a lumen that only just admits the passage of red blood cells. Intercellular junctions join adjacent endothelial cells. The microcirculation is adapted to each organ and tissue. Thus, the liver sinusoids and kidney have a highly permeable fenestrated endothelium, whereas the capillaries in the brain are watertight and contribute to the blood–brain barrier. Capillary endothelial cells are surrounded by pericytes, which support them, synthesize basement membrane, and can differentiate into a variety of cell types including vascular smooth muscle cells. Capillaries act as a semipermeable membrane. They retain most of the protein but permit free exchange of fluid.
Diagnostics of Functional Abnormalities in the Microcirculation System Using Laser Doppler Flowmetry
Andrey V. Dunaev, Valery V. Tuchin in Biomedical Photonics for Diabetes Research, 2023
The main function of the microcirculation is to transport blood and substances to and from tissues. When the blood moves along the capillary, a huge number of water molecules and dissolved particles diffuse in one direction and in the other through the capillary wall, ensuring constant mixing of the tissue fluid and plasma. The permeability of capillaries for various substances is different and depends on the size of their molecules and the type of capillaries themselves. One of the most important purposes of delivering oxygen to the tissues is achieved by blood transport. Cells are constantly in need of oxygen, which they receive by diffusion from the blood through the interstitial fluid. The primary function of the blood is to deliver oxygen to tissues. The circulatory system pumps oxygen-rich blood through the capillary network. The microcirculatory system is organized in such a way that all cells have at least one adjacent capillary for diffusive oxygen exchange, and red blood cells deliver oxygen to the tissues as they pass through the capillaries [24].
Intervention of 3D printing in health care: transformation for sustainable development
Published in Expert Opinion on Drug Delivery, 2021
Sujit Kumar Debnath, Monalisha Debnath, Rohit Srivastava, Abdelwahab Omri
A lot of researches are carried out in the field of tissue engineering to generate new functional tissue using live cells and scaffolding. It comprises the development of a biological substitute to whole organs or tissue transplantation. 3D painting gives a potential solution for the growing concern of patients die due to a lack of organ transplantation and a shortage of organ donors [77]. The revolution of 3D printing technology helps to replicate natural skin structures at a lower price. This skin is successfully used in the testing of pharmaceutical products like cosmetics, chemical products. Thus, this advancement prevents the unnecessary use of animal skin to evaluate any product [46]. The importance of in vivo vascularization is increasing with micro-scale geometry. Microvasculature creates a complex network that exchanges nutrients to arterioles, capillaries, and venues. Therefore, the interest is growing to promote cell viability and drug response by incorporating vasculature [79]. 3D microfluidics prepared by digital light processing, stereolithography apparatus can be transparent and easy to observe. The micro-channel prepared by these techniques is accurate and suitable for varieties of module interfaces. 3D printing serves as a useful platform to analyze the drug penetration and metabolism by allowing dynamic dosing in cell culture (spheroids). Among the 3D cell cultures, multicellular tumor spheroid is the most commonly employed spheroids. These spheroids can grow to 1 mm in diameter and demonstrate heterogeneous microregions like in-vivo tumors [80].
Impact of tetraplegia vs. paraplegia on venoarteriolar, myogenic and maximal cutaneous vasodilation responses of the microvasculature: Implications for cardiovascular disease
Published in The Journal of Spinal Cord Medicine, 2022
Michelle Trbovich, Yubo Wu, Wouter Koek, Joan Zhao, Dean Kellogg
Structural remodeling of the macrocirculation occurs as soon as 3–6 weeks after SCI consisting of decreased large vessel diameters and increased arterial stiffness.1–5 While such rapid and extensive remodeling of large conduit vessels is well established, structure and function of the microvasculature, has been less explored. Abnormalities in the microvasculature are demonstrable in the cutaneous microcirculation of persons at high risk of cardiovascular disease (CVD).6 Since the prevalence of CVD is higher in SCI persons than their able-bodied (AB) counterparts and is a leading cause of mortality in persons with SCI, greater understanding of the microvasculature after SCI is essential.6,7 More specifically, whether the microcirculation follows the same pattern as the macrocirculation is unknown. Maximal cutaneous vasodilation occurs when smooth muscle is fully relaxed with local skin heating of 42°C.8,9 Maximal cutaneous vasodilation responses are reduced in persons with microvascular disease from diabetes, hypertension, end organ damage and cardiovascular disease.6,7,10–12 The impact of SCI on maximal cutaneous vasodilation responses is not well defined, however given the cutaneous circulation is easily accessible, examining them is relatively safe and can yield valuable information of their contribution to the high mortality from CVD in this population.
Bias and Non-Diversity of Big Data in Artificial Intelligence: Focus on Retinal Diseases
Published in Seminars in Ophthalmology, 2023
Cris Martin P Jacoba, Leo Anthony Celi, Alice C. Lorch, Ward Fickweiler, Lucia Sobrin, Judy Wawira Gichoya, Lloyd P Aiello, Paolo S. Silva
Diversity in retinal image databases is essential as there are clear anatomical differences in fundus appearance and disease pathology between different ethnicities. On average, patients of African descent have darker fundus pigmentation than patients of White European descent due to the elevated concentration of melanin within uveal melanocytes.23 These histologic differences are also apparent in optical coherence tomography (OCT) imaging, where eyes of African descent have greater choriocapillary visibility, while eyes of White descent have greater choroidal-scleral junction visibility. Retinal vascular parameters between a multiethnic Asian population (Indian, Malay and Chinese) differed significantly among the three groups.24 The Indian cohort had the widest venular and arteriolar calibers, while the Chinese cohort had the most vessel tortuosity. The variation between populations is linked to systemic issues that include hypertension, diabetes, and stroke risk. These parameters have been proposed as an area of research to understand the link between systemic disease and the microvasculature.25–29 A nuanced understanding of baseline inter-ethnic differences must be incorporated in ML approaches to study vascular parameters in order to arrive at accurate conclusions.
Related Knowledge Centers
- Arteriole
- Tissue
- Vein
- Venule
- Capillary
- Circulatory System
- Blood
- Blood Vessel
- Metarteriole
- Lymph Capillary