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Blood Pressure Physiology (view source)
Revision as of 10:02, 26 October 2010
, 10:02, 26 October 2010→Autonomic nervous system (ANS) responses
4) [[Kidney - Blood Pressure - Anatomy & Physiology|Kidney]] and fluid balance mechanisms
4) [[Kidney - Blood Pressure - Anatomy & Physiology|Kidney]] and fluid balance mechanisms
==Autonomic nervous system (ANS) responses==
Normal circulatory homeostasis depends upon there being a basal level of activity in both the sympathetic and parasympathetic nervous systems - the ANS is controlled by the cardioinhibitory and vasomotor centres within the medulla oblongata . The ANS is the most '''rapidly responding regulator''' of blood pressure.
Normal circulatory homeostasis depends upon there being a basal level of activity in both the sympathetic and parasympathetic nervous systems - the ANS is controlled by the cardioinhibitory and vasomotor centres within the medulla oblongata . The ANS is the most '''rapidly responding regulator''' of blood pressure.
==='''''Stimulus for activation'''''===
A drop in cardiac output results in a drop in arterial blood pressure, which is sensed by baroreceptors (pressure-sensitive nerve endings) located in the carotid sinus and aortic arch. A drop in signals from the baroreceptors to the vasomotor centre (VMC) of the brainstem in response to perceived hypoperfusion leads to a centrally controlled increase in activity of the sympathetic nervous system and an increased release of adrenaline from the adrenal medulla.
A drop in cardiac output results in a drop in arterial blood pressure, which is sensed by baroreceptors (pressure-sensitive nerve endings) located in the carotid sinus and aortic arch. A drop in signals from the baroreceptors to the vasomotor centre (VMC) of the brainstem in response to perceived hypoperfusion leads to a centrally controlled increase in activity of the sympathetic nervous system and an increased release of adrenaline from the adrenal medulla.
==='''''Response to stimulus'''''===
Adrenaline released from the adrenal medulla into the circulation, and noradrenaline released at nerve terminals, stimulates cardiac and vascular '''alpha and beta-receptors''', resulting in vasoconstriction of both the arterial and venous side of the circulation (alpha-receptors) and increased contractility of the heart (beta-receptors).
Adrenaline released from the adrenal medulla into the circulation, and noradrenaline released at nerve terminals, stimulates cardiac and vascular '''alpha and beta-receptors''', resulting in vasoconstriction of both the arterial and venous side of the circulation (alpha-receptors) and increased contractility of the heart (beta-receptors).