Mean Arterial Pressure
Mean Arterial Pressure (MAP) is the average arterial pressure throughout one cardiac cycle (systole and diastole).
Can be calculated using a Formula:
MAP = DP + 1/3(SP - DP)
SP systolic pressure
DP diastolic pressure
MAP is normally between 60 and 110 mmHg.
If MAP below 60 mmHg for an extended period, end-organ manifestations such as ischemia and infarction can occur.
Mechanisms of regulating:
- Synthesis of nitric oxide (NO) in endothelial cells, bradykinin and the various prostaglandins leads to smooth muscle relaxation and dilation of the vessel.
- Endothelin is a local vasoactive compound leads to calcium release from the sarcoplasmic reticulum, which leads to smooth muscle contraction and constriction of the vessel
- The arterial baroreceptors found in the carotid sinus and aortic arch communicate with nucleus tractus solitarius in the medulla of the brainstem via the glossopharyngeal nerve (cranial nerve IX) (either raise or lower MAP)
- Renin-angiotensin-aldosterone cascade. Aldosterone acts on the distal convoluted renal tubules to increase sodium reabsorption and therefore increase water reuptake.
- Angiotensin II acts on the vasculature via the AT1 receptor to induce smooth muscle contraction, resulting in vasoconstriction.
