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A diagram explaining factors affecting arterial pressure. Pathophysiology is a study which explains the function of the body as it relates to diseases and conditions. The pathophysiology of hypertension is an area which attempts to explain mechanistically the causes of hypertension, which is a chronic disease characterized by elevation of blood pressure.
Hyperviscosity syndrome is a group of symptoms triggered by an increase in the viscosity of the blood.Symptoms of high blood viscosity include spontaneous bleeding from mucous membranes, visual disturbances due to retinopathy, and neurologic symptoms ranging from headache and vertigo to seizures and coma.
The causes of this condition are not well understood, but research suggests that it may be caused by a combination of hemodynamic and neurohumoral factors. [8]Some studies have found that orthostatic hypertension may be caused by increased vascular resistance, possibly due to excess plasma shifts or increased blood viscosity.
Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much oxygen is transported to tissues and organs.
Blood pressure varies over longer time periods (months to years) and this variability predicts adverse outcomes. [18] Blood pressure also changes in response to temperature, noise, emotional stress, consumption of food or liquid, dietary factors, physical activity, changes in posture (such as standing-up), drugs, and disease. [19]
The narrowing of the lumen can decrease renal blood flow and hence glomerular filtration rate leading to increased renin secretion and a perpetuating cycle with increasing blood pressure and decreasing kidney function. [12] The brain is another organ where hyaline arteriolosclerosis occurs prematurely in patients with high blood pressure.
In the arterioles blood pressure is lower than in the major arteries. This is due to bifurcations, which cause a drop in pressure. The more bifurcations, the higher the total cross-sectional area, therefore the pressure across the surface drops. This is why [citation needed] the arterioles have the highest pressure-drop. The pressure drop of ...
A hypertensive emergency is not based solely on an absolute level of blood pressure, but also on a patient's baseline blood pressure before the hypertensive crisis occurs. Individuals with a history of chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension , including fatigue ...