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Even at resting levels of blood pressure, arterial baroreceptor discharge activates SN neurons. Some of these SN neurons are tonically activated by this resting blood pressure and thus activate excitatory fibers to the nucleus ambiguus and dorsal nucleus of vagus nerve to regulate the parasympathetic nervous system.
Baroreceptors respond very quickly to maintain a stable blood pressure, but their responses diminish with time and thus are most effective for conveying short term changes in blood pressure. In people with essential hypertension the baroreceptors and their reflexes change and function to maintain the elevated blood pressure as if normal. The ...
An antihypotensive, also known as vasopressor, is an agent that raises blood pressure by constricting blood vessels, thereby increasing systemic vascular resistance. This is different from inotropes which increase the force of cardiac contraction. Some substances do both (e.g. dopamine, dobutamine).
Cardiac output (CO) is affected by two factors, the heart rate (HR) and the stroke volume (SV), the volume of blood pumped from one ventricle of the heart with each beat (CO = HR × SV, therefore BP = HR × SV × TPR). In reflex bradycardia, blood pressure is reduced by decreasing cardiac output (CO) via a decrease in heart rate (HR). [citation ...
When blood pressure falls many physiological cascades commence in order to return the blood pressure to a more appropriate level. The blood pressure fall is detected by a decrease in blood flow and thus a decrease in glomerular filtration rate (GFR). Decrease in GFR is sensed as a decrease in Na + levels by the macula densa.
For most people, recommendations are to reduce blood pressure to less than or equal to somewhere between 140/90 mmHg and 160/100 mmHg. [2] In general, for people with elevated blood pressure, attempting to achieve lower levels of blood pressure than the recommended 140/90 mmHg will create more harm than benefits, [3] in particular for older people. [4]
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Pulse pressure is calculated as the difference between the systolic blood pressure and the diastolic blood pressure. [3] [4]The systemic pulse pressure is approximately proportional to stroke volume, or the amount of blood ejected from the left ventricle during systole (pump action) and inversely proportional to the compliance (similar to elasticity) of the aorta.