The physiology and hemodynamics of the normal venous circulation
Peter Gloviczki, Michael C. Dalsing, Bo Eklöf, Fedor Lurie, Thomas W. Wakefield, Monika L. Gloviczki in Handbook of Venous and Lymphatic Disorders, 2017
The primary purpose of the venous circulation is to return blood to the heart for reoxygenation and recirculation. Understanding volume and pressure relationships is essential for understanding normal and abnormal venous function. The enormous capacity of the venous reservoir plays a major role in the maintenance of cardiovascular homeostasis by accommodating volume shifts. Regulation of venous tone is an important aspect of volume accommodation and works in concert with arterial control mechanisms that effect changes in the distribution of cardiac output. Sympathetic-mediated adjustments of smooth muscle tone are most pronounced in the splanchnic and cutaneous distributions, which are also the most densely innervated. In the upright posture, the physiological effects of gravity and hydrostatic pressure would appear to oppose return flow, but these effects are largely offset by competent valvular function and an efficient peripheral pump mechanism.
Electrophysiology
A. Bakiya, K. Kamalanand, R. L. J. De Britto in Mechano-Electric Correlations in the Human Physiological System, 2021
The cardiopulmonary system consists of blood vessels that carry nutrients and oxygen to the tissues and removes carbon dioxide from the tissues in the human body (Humphrey & McCulloch, 2003; Alberts et al., 1994). Blood is transported from the heart through the arteries and the veins transport blood back to the heart. The heart consists of two chambers on the top (right ventricle and left ventricle) and two chambers on the bottom (right atrium and left atrium). The atrioventricular valves separates the atria from the ventricles. Tricuspid valve separates the right atrium from the right ventricle, mitral valve separates the left atrium from the left ventricle, pulmonary valve situates between right ventricle and pulmonary artery, which carries blood to the lung and aortic valve situated between the left ventricle and the aorta which carries blood to the body (Bronzino, 2000). Figure 3.9 shows the schematic diagram of heart circulation and there are two components of blood circulation in the system, namely, pulmonary and systemic circulation (Humphrey, 2002; Opie, 1998; Milnor, 1990). In pulmonary circulation, pulmonary artery transports blood from heart to the lungs. The blood picks up oxygen and releases carbon dioxide at the lungs. The blood returns to the heart through the pulmonary vein. In the systemic circulation, aorta carries oxygenated blood from the heart to the other parts of the body through capillaries. The vena cava transports deoxygenated blood from other parts of the body to the heart.
Basic medicine: physiology
Roy Palmer, Diana Wetherill in Medicine for Lawyers, 2020
The heart is the muscular pump that drives blood around the body. It has long been known that blood will spurt from a cut artery under high pressure, but it was thought to oscillate to and fro until William Harvey showed that blood circulates from small arterial branches through tiny vessels in the tissues (capillaries) before being collected by veins and returned to the heart The dynamo behind this circulation is the heart, which contracts 60–80 times per minute throughout an individual’s life. The heart contains four chambers and is responsible for two separate circulatory systems (Figure 1.1). The systemic circulation supplies all the organs in the body with oxygenated blood, while the pulmonary circulation delivers exhausted blood to the lungs where it is replenished with oxygen. The heart chambers comprise two atria which collect the blood and pass it through valves into the two ventricles, which contract forcefully to distribute blood throughout the body. The cardiac cycle consists of diastole, the phase of filling, and systole in which contraction of the atria is immediately followed by contraction of the ventricles.
Novel formulations of metal-organic frameworks for controlled drug delivery
Published in Expert Opinion on Drug Delivery, 2022
Congying Rao, Donghui Liao, Ying Pan, Yuyu Zhong, Wenfeng Zhang, Qin Ouyang, Alireza Nezamzadeh-Ejhieh, Jianqiang Liu
More accurate optimization on the size, morphology, surface characteristics, etc. To ensure the extension of the blood circulation, stability under physiological conditions, control cargo release, enhance cell absorption, and in vivo system targeted administration. Although the MOF surface has made significant progress in engineering, many types of MOFs are still limited in the aqueous solution and buffer solution, which hinders drug-controlled release. In terms of MOF, the synthesis of MOF is mainly under the heat conditions of high boiling point. It is carried out in polar solvents, such as dimethylformamide (DMF) and diethylformamide (DEF) [194]. Due to the increased environmental issues and growing demand for sustainable products and processes, introducing/developing more green methods (for reducing waste generation, organic solvent-free techniques, producing fewer hazard by-products) is a critical issue [195–197].
Modelling and simulation of fluid flow through stenosis and aneurysm blood vessel: a computational hemodynamic analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
J. V. Ramana Reddy, Hojin Ha, S. Sundar
Blood vessels play an important role in the circulatory system; These are in the form of tubes that carry blood between the heart and all parts of the body. The blood vessel size varies enormously; in the case of arteries, it varies from 1 mm to 8 µm while 1 mm to 20 µm for veins. An artery carries oxidized blood away from the heart, whereas a vein is the blood vessel that collects and transports blood toward the heart. The general appearance of the arteries is rounded lumen, while veins are irregular and often collapse. As compared to arteries, veins are thin-walled vessels with a large and irregular lumen. The diseases of arteries, veins, and lymph vessels alert to blood flow disorders that affect circulation, thus resulting in disturbance in organ function. An aneurysm is a pathological condition. It weakens the blood vessel wall due to the bulging area in that area, resulting in an abnormal widening or ballooning more significant than 50% of the standard diameter. The arteries are mostly exposed to an aneurysm rather than a vein among the several blood vessels.
Right Ventricular-Pulmonary Arterial Coupling and Outcomes in Heart Failure and Valvular Heart Disease
Published in Structural Heart, 2021
Bahira Shahim, Rebecca T. Hahn
Compared with the systemic circulation, pulmonary circulation has a much lower vascular resistance, greater pulmonary artery distensibility, and a lower peripheral pulse wave reflection coefficient.12 Pulmonary vascular impedance reflects the opposition to pulsatile flow, and determines, together with pulmonary vascular resistance (PVR), the RV afterload.9 RV afterload is reflected by arterial elastance (Ea), a load-independent measure of “total” ventricular afterload (both pulsatile and resistive components). It is measured as RV end-systolic pressure divided by stroke volume.24 PVR is a measure of the resistance of both capillaries and veins and is calculated as the difference between the mean pulmonary arterial pressure and pulmonary capillary wedge pressure, divided by the cardiac output. In the normal RV, mean pulmonary artery pressure is a reasonable approximation of end-systolic pressure. Thus, in the normal RV Ea could be estimated as PVR x heart rate.25 Although PVR represents only the resistive component of Ea, and pulmonary arterial compliance represents the pulsatile component, the latter contributes only ~23% to total afterload26 in normal patients and those with arterial pulmonary hypertension (PH) and support the use of the simplified formula. However, if post-capillary PH is present, the pulsatile component of Ea increases27 and stroke work is significantly reduced.28 Taking into account both resistive and pulsatile components of Ea may then be more important.