Understanding How The Nervous System Regulates Blood Pressure :
Our blood pressure is regulated from minute to minute by nerves. At specific locations in the walls of the large arteries, special sensors "measure" blood pressure by responding to the amount of stretch in the walls of the arteries. An important location of these sensors is the carotid sinus, which is in the arteries that run up the neck to supply the head with blood.When you suddenly sit or stand up after lying down. Gravity pulls the blood downward, lowering the blood pressure in the carotid sinus in your neck. If the carotid sinus reflex didn't act promptly, sending out nerve impulses (over sympathetic nerves) to increase heart output and constrict the arterioles, you would faint from the decreased flow of blood to your head.
Located along portions of the carotid artery and the aorta are several hundred pressure detectors called baroreceptors. These specialized cells operate like ‘stretch’ detectors that respond to alterations in blood pressure in the arteries and send neural signals to the brainstem to inform the brain which component of the autonomic nervous system should fire. Inadequate blood pressure should result in a signal to increase either heart rate or vasoconstriction via the sympathetic nervous system.
# Your blood pressure changes when you change position.
# When your heart contracts, it pushes blood into the arteries causing an increase in blood pressure (systolic pressure). When your heart relaxes and refills with blood, the pressure in the arteries decreases (diastolic pressure).
# Standing causes 500 to 700 ml of blood to pool in the legs, so there is less blood for the heart to pump. This results in a decrease in blood pressure.
# Special cells called baroreceptors (located close to the neck arteries) sense this decrease in blood pressure. They counteract by triggering the heart to beat faster and pump more blood in order to stabilize the blood pressure.
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