Blood pressure regulation
How our body compensate the sudden elevation of blood pressure
Increased blood pressure will stretch the baroreceptors located in the aortic and carotid sinuses.
The baroreceptors in turn will stimulate the cardioinhibitory centre in the medulla oblongata
Which will enhance the parasympathetic activities through vagus nerve.
This results in decreased heart rate or bradycardia
Stretching the baroreceptors also supress the vasomotor centre in medulla oblongata and the sympathetic stimulation of the blood vessels
Which results in vasodilation
Additionally, increased blood pressure will increase the cardiac output
And Atrial natriuretic peptide hormones
Both supress the renin angiotensin aldosterone system (RAAS)
This suppression results in increased water and sodium excretion by the kidney
Which leads to decreased blood volume
Additionally, suppression of angiotensin II results in vasodilation
All these autoregulatory mechanisms results in returning of blood pressure to normal levels
Now we will study the autoregulatory mechanism in case of hypotension
If the blood pressure decreases the baroreceptors stretching will be decreased
Consequently, the shrunk baroreceptors will stimulate the cardiac accelerator centre in medulla oblongata
Which will stimulate the sympathetic output
Which increases the heart rate.
Decrease stretching in the baroreceptors will also enhance the sympathetic stimulation to peripheral blood vessels
To induce vasoconstriction
Thus, normal blood pressure will be elevated to near normal levels
Additionally, decreased cardiac output
Will supress the atrial natriuretic hormone
Both factors lead to stimulation of renin angiotensin aldosterone system
And less water and sodium will be excreted into the urine
Thus, blood volume will be increased
Additionally, angiotensin II induces peripheral vasoconstriction
These autoregulatory mechanisms will result in returning of blood pressure to normal levels