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Endothelial cells within blood vessels can alter the strength of their structure to maintain the vascular tone of the blood vessel they line, prevent vascular rigidity, and even help to regulate blood pressure within the cardiovascular system. Endothelial cells accomplish these feats by using depolarization to alter their structural strength.
The classical explanation of HPV involves inhibition of hypoxia-sensitive voltage-gated potassium channels in pulmonary artery smooth muscle cells leading to depolarization. [ 3 ] [ 4 ] This depolarization activates voltage-dependent calcium channels , which increases intracellular calcium and activates smooth muscle contractile machinery which ...
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported.The current through HCN channels, called the pacemaker current (I f), plays a key role in the generation and modulation of cardiac rhythmicity, [13] as they are responsible for the spontaneous depolarization in pacemaker action potentials in the heart.
The type I (glomus) cells in the carotid (and aortic bodies) are derived from neuroectoderm and are thus electrically excitable. A decrease in oxygen partial pressure, an increase in carbon dioxide partial pressure, and a decrease in arterial pH can all cause depolarization of the cell membrane, and they affect this by blocking potassium currents.
It is also possible that a high degree block can result after cardiac surgery during which the surgeon was in close proximity to the electrical conduction system and accidentally injured it. Reversible causes of Mobitz II and third-degree heart block include untreated Lyme disease , hypothyroidism , hyperkalemia (high levels of potassium), and ...
This system is especially significant in the kidneys, where the glomerular filtration rate (the rate of blood filtration by the nephron) is particularly sensitive to changes in blood pressure. However, with the aid of the myogenic mechanism, the glomerular filtration rate remains very insensitive to changes in human blood pressure.
The aortic bodies measure partial gas pressures and the composition of arterial blood flowing past it. [7] These changes may include: oxygen partial pressure. [7] [8]carbon dioxide partial pressure.