Arterial Blood PressureANATOMY & PHYSIOLOGY 13-14

点脉 Dim Mak = “Press Artery”

Pressure Point Fighting

Arterial Blood Pressure WHAT IT IS:

Def: Measurement of the pressure exerted by the fluid medium (blood) on the interior walls of the circulatory vasculature

Measured as variance between:◦ Systolic (high)◦ Diastolic (low)

Arterial Flow Primarily carrying oxygenated blood away from body

Vasculature is more muscular with elastic fibers to prevent distension (stretching out)

Visceral muscle of arteries can contract to maintain blood pressure

FILTRATION 20 l/day enters capillaries

17 l/day leaves

3 l/day directed to lymphatic system

Venous Circulation 60%-65% of blood currently venous return

Valves (similar to semilunar valves) prevent backflow of blood

SURFACE AREA OF VASCULATURE V. VELOCITY OF BLOOD FLOW

As the surface area of the vasculature increases the velocity drops

As the total distance from the heart increases, velocity decreases (but not consistently)

Assessment of Arterial Blood Pressure

Measured in millimeters of mercury (mmHg)

Ratio of systolic/diastolic (i.e. 120/80)

SYSTOLE v. DIASTOLE Systole is the period of time in circulatory physiology defined by the following events:

Electrical Systole = QRS complex of EKG

Mechanical Systole = contraction of ventricular myocardium

Arterial Systole = blood ejected into aorta via aortic semilunar valve and pulmonary artery via pulmonary semilunar valves from the left and right ventricles respectively

Diastole is the period of time in circulatory physiology defined by the following events:

Electrical Diastole = P wave of EKG

Mechanical Diastole = contraction of atrial myocardium

Arterial Diastole = blood ejected into right ventricle from right atrium via tricuspid valve while simultaneous movement of blood from left atrium into left ventricle via bicuspid valve

Where and how is blood pressure regulated by the body?

Baroreception Baroreceptors located in the carotid sinus measure the arterial blood pressure

Messages sent from baroreceptors to the medulla oblongata via the Glossopharyngeal nerve

Return pathway to sino-atrial node via the Vagus nerve

VASOREGULATION Vasodilation = increase diameter of vasculature

Vasoconstriction = decrease diameter

How is arterial blood pressure assessed externally?

SphygmomanometryAUSCULTATION

Manually listen for Kortokoff sounds while pressure is released on artery

OSCILLATION

Electronically sense oscillations in blood flow that correspond with cardiac events

Mean Arterial Pressure (MAP)