Blood Pressure

Contents 1 Basic Concepts 2 Regulation of Blood Pressure 3 Fast Term Mechanism 4 Long Term Mechanism 5 Summary 6 References

edit Basic Concepts

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

edit Regulation of Blood Pressure

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

edit Fast Term Mechanism

• 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

edit Long Term Mechanism

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

edit Summary

• 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…

edit References

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]