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Respond to stretch caused by blood pressure
Higher pressure produces more nerve impulses/sec;
Carotid sinus: sensory nerve = cranial nerve IX (glossopharyngeal)
Aortic arch: sensory nerve = cranial nerve X (vagus)
„h Sensors: pressure sensors in the arteries of the upper body:
„h Respond to stretch caused by blood pressure
„h Higher pressure produces more nerve impulses/sec; lower blood pressure causes fewer nerve impulses/sec
„h Carotid sinus: sensory nerve = cranial nerve IX (glossopharyngeal)
„h Aortic arch: sensory nerve = cranial nerve X (vagus)
„h Integrating Center: medulla oblongata of the brain
„h Sensory nerves go to nucleus tractus solitarius
„h Detected blood pressure is compared with desired pressure (set point)
„h Centers used to correct blood pressure:
„h Cardiac accelerator center: increases cardiac output: uses cardiac accelerator nerve
„h Cardiac inhibitor center: decreases cardiac output: uses vagus nerve
„h Vasoconstrictor center: constricts arterioles and veins: uses spinal nerves
„h Constriction of blood vessels raises resistance to flow (R)
„h Effectors: Heart:
„h SA Node: controls heart rate (HR)
„h Vagus nerve slows heart
„h Cardiac accelerator speeds up heart
„h Heart muscle: controls stroke volume (SV)
„h Cardiac accelerator nerve increases SV
„h No vagus fibers go to heart muscle
„h Arteries & veins
„h Results: If pressure is low:
„h Reflex will increase cardiac output (CO = HR X SV)
„h Reflex will constrict arterioles & veins
„h If pressure is high:
„h Reflex will decrease CO
„h Decreased reflex activity will dilate arterioles and veins
„h Reflex will restore correct blood pressure
„h P = CO X R
BIBILIOGRAPHY:
Text book of physiology(21st edition)-[976-981]
Human physiology-Jennet-{182-183]
Human physiology(basis of medicine) Gillian Pocock and Christopher D. ...
Cardiovascular physiology by Hans-Joachim and Karl{222-225]
Introduction to cardiovascular physiology by Levick {334-337]
B.
Approximate Word count = 1771
Approximate Pages = 7.1
(250 words per page double spaced)
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