39. Control of the arterial blood pressure. Mechanisms of the quick short-term, quick ongoing, and long-term regulation.

arterial blood pressure

Mean arterial blood pressure is P) is the average pressure at each moment during

one cardiac cycle: MAP =DBP +1/3 PP

àDBP= diastolic blood pressure which is the minimum blood pressure value during a

cardiac cycle 60-90mmHg

àPP= pulse pressure which is the difference between the values of the systolic and diastolic

pressure: PP= SBP – DBP

SBP= is the maximum blood pressure value during a cardiac cycle 100-140mmHg

=Normal MAP is 70-100mmHg

Mechanisms of the quick short-term regulation: / quick ongoing

- Sympathetic NS by adrenaline acting of B1 receptors à increases the excitability

(batmotropic), contractility (chromotropic), velocity (dromotropic), tonus (tonotropic), and

heart rate (ionotripic). Increases heart rate à increases cardiac output à increase BP

- Parasympathetic NS by noradrenaline acting on M2 receptors à decreases the the

excitability (batmotropic), contractility (chromotropic), velocity (dromotropic), tonus

(tonotropic), and heart rate (ionotripic)

- Vasomotor receptors = controls the vasocontractions and vasodilation of the blood

vessels

- Baroreceptors = monitor blood pressure in the carotid sinus and the aorta. If the arterial

blood pressure is increased, it will stimulate the vagus nerve. If the arterial blood pressure is

decreased, it will stimulate the sympathetic nervous system.

Mechanisms of quick on-going regulation: -Renin-angiotensin system à when the blood pressure is low, the kidneys detect the change and secrete renin which then leads to a cascade of reactions to form angiotensin II. =Secretion of aldosterone, vasopressin, and increases the sense of thirst

long term + WHAT IS BLOOD PRESSURE

Mechanisms of long-term regulation:

-Aldosterone à acts in kidneys; produces Na+ channels and K+ channels= Na+ and H2O

will get reabsorbed, K+ will get secreted

-Vasopressin à acts in kidneys; produces aquaporins for water retention = increased blood

pressure

-Thirst

The standard units for measuring the blood pressure are millimeters of mercury (mm Hg) or kPa.

Actually blood pressure means the force exerted by the blood against any unit area of the vessel

wall. When one says that the pressure in the vessel is 100 mm Hg, this means that the force exerted is

sufficient to push a column of mercury up to a level 100 mm high

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