Physiology of the cardiovascul essays

Physiology of the cardiovascul essays The Cardiovascular System-Blood Pressure and The ECG Blood pressure is the force of blood distending the arterial walls. Blood pressure is measured in the Brachial artery using a sphygmomanometer, the average resting bp in a normal person is 120/80. The higher number is the systolic blood pressure (SBP), which is produced as blood is expelled from the heart during ventricular systole. The lower number indicates diastolic blood pressure (DBP), this corresponds to the pressure being exerted on the blood vessels during the relaxation phase (diastole) of the cardiac cycle. Blood is delivered to all tissues of the body by maintaining arterial blood pressure, which is dependent on cardiac output (volume of blood pumped by the heart per minute) and peripheral resistance (which is increased by constriction and decreased by dilation of the arterioles). Blood pressure is controlled by chemoreceptors which signal to the vasomotor center in brain causing vasoconstriction as well as barorecepteors. Humans have myelinated Baroreceptors, found in the carotid artery in the neck, the pulmonary arteries and in the aortic arch. They respond to stretch in arterial walls caused by changes in blood pressure. The set point for blood pressure can be changed by other receptor inputs or other inputs to the brain (8). Arterial blood pressure increases and decreases with every heart beat, baroreceptors in the carotid artery are sensitive to oscillations in the normal range of 1-10 H and pressure changes from 60-180 mmHg. Rate of pressure change as well as to the steady or mean pressure are detected. If the pulse pressure decreases,baroreceptor firing rate also decreases This is important during conditions such as hemorrhagic shock where pulse pressure as well as mean pressure decreases. Therefore, a combination of reduced mean pressure and pulse pr essure reinforces the baroreceptor reflex. Compliance (The ability of a blood vessel wall to expand and c...