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Transmural pressure is the difference in pressure between two sides of a wall or equivalent separator. According to myogenic theory smooth muscle contract in response to increased transmural pressure and relax to decreased transmural pressure For body vasculature or other hollow organs, see Smooth muscle#External substances
Critical closing pressure is the internal pressure at which a blood vessel collapses and closes completely. [1] When blood pressure falls below critical closing pressure, the vessel is unable to overcome external pressure (either from environment or vascular smooth muscle) and flow stops.
On the other hand, gravity causes a gradient in blood pressure between the top and bottom of the lung of 20 mmHg in the erect position (roughly half of that in the supine position). Overall, mean pulmonary venous pressure is ~5 mmHg. Local venous pressure falls to -5 at the apexes and rises to +15 mmHg at the bases, again for the erect lung.
Veins (/ v eɪ n /) are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart.Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal circulations which carry oxygenated blood to the heart.
Veins carry "used or spent" blood back to the heart, to remove carbon dioxide, lactic acid, and other metabolic products. The neurovascular unit regulates cerebral blood flow so that activated neurons can be supplied with energy in the right amount and at the right time. [ 1 ]
The converse argument is that generally artery walls are thicker and more muscular than veins as the blood passing through is of a higher pressure. This means that it would take longer for any oxygen to diffuse through to the cells in the tunica adventitia and the tunica media, causing them to need a more extensive vasa vasorum.
The increase in pulse pressure may result in increased damage to blood vessels in target organs such as the brain or kidneys. [23] [24] This effect may be exaggerated if the increase in arterial stiffness results in reduced wave reflection and more propagation of the pulsatile pressure into the microcirculation. [23]
It can cause the affected limb to swell, and cause pain and an overlying skin rash. In the worst case, a deep vein thrombosis can extend, or a part of a clot can break off as an embolus and lodge in a pulmonary artery in the lungs, known as a pulmonary embolism .The decision to treat deep vein thrombosis depends on its size, a person's symptoms ...