Blood Pressure

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Basic Concepts[edit | edit source]

Blood Pressure – the force exerted by the blood against any unit of area of the vessel wall (in mmHg)

During each heartbeat, the BP changes between 2 values:

  • a maximum – SYSTOLIC PRESSURE – pressure when the heart releases the blood in the vessels - about 120 mmHg
  • a minimum – DIASTOLIC PRESSURE – pressure in the blood vessels between each heartbeat (when the heart is resting) - about 80 mmHg

Pulse Pressure – difference between systolic and diastolic pressures (40 mmHg)

Mean Arterial Pressure (MAP) – the average pressure within an artery over a complete cycle of one heartbeat

MAP = Diastolic Pressure + 1/3 Pulse Pressure

Total Peripheral Resistance - sum of resistance of all peripheral vasculature in systemic circulation


Regulation of Blood Pressure[edit | edit source]

There are 2 main mechanisms that regulate blood pressure:

  • Short/Fast Term Mechanism - Neurally mediated baroreceptor mechanism that regulate blood vessel diameter, heart rate and contractility
  • Slower/Long Term Mechanism - Hormonally regulated renin-angiotensin-aldosterone mechanism that regulate blood volume


Fast Term Mechanism[edit | edit source]

  • Is a negative feedback system that is responsible for the minute to minute regulation of arterial blood flow
  • The sensor for MAP is provided by baroreceptors (stretch receptors) located in the carotid sinus and aortic arch
  • Sensitive between 80 – 150 mmHg


Long Term Mechanism[edit | edit source]

  • Slow hormonal mechanism by adjustment of blood volume
  • Renin – angiotensin – aldosterone System

Bloodpressure.jpg

Summary[edit | edit source]

  • BP: FORCE EXERTED BY BLOOD AGAINST ANY UNIT AREA OF THE VESSEL WALL
  • BP HAS DIFFERENT VALUE THROUGH THE CIRCULATORY SYSTEM
  • ARTERIAL PRESSURE PULSATION: 120/80 mmHg
  • REGULATION VIA AUTONOMIC AND HORMONAL SYSTEM
  • BP IS CONTINUALLY CHANGING DEPENDING ON ACTIVITY, TEMPERATURE, DIET, PHYSICAL OR EMOTIONAL STATE, MEDICATION…


References[edit | edit source]

Guyton, Arthur C.; Hall, John E. Guyton and Hall textbook of medical physiology. 12th ed. USA: Saunders, 2011. GUYTON, Arthur C, et al. Textbook of Medical Physiology. 12th edition. USA : Saunders, 2011. [1] [2]