Blood Pressure

Blood pressure (BP) A constant flow of blood is necessary to transport oxygen to the cells of the body The arteries maintain an average blood pressure of around 90 mmHg This helps push the blood from the arteries into the capillaries In the capillaries, oxygen transfers from the blood to the cells

Systole and Diastole The arteries fluctuate between a state of: In systole, the pressure in the arteries increases as the heart pumps blood into the arterial system. As the pressure increases, the elastic walls of the arteries stretch This can be felt as a pulse in certain arteries Maximum systolic pressure is typically 110-120 mmHg

Systole and Diastole The arteries fluctuate between a state of: In diastole, the recoil of the elastic arteries forces blood out of the arterial system into the capillaries The pressure in the arteries falls as blood leaves the system Minimum diastolic pressure is typically 70-80 mmHg

Systole and Diastole Systolic pressure – pressure exerted on arterial walls during ventricular contraction Diastolic pressure – lowest level of arterial pressure during a ventricular cycle Pulse pressure – the difference between systolic and diastolic pressure

Baroreceptors How does the body know that there has been a fall in blood pressure? Baroreceptors on the aorta and carotid artery respond to falls in BP They send signals to the cardiovascular centre in the brain stem medulla The medulla sends signals along the sympathetic nerves to the arterioles and heart, increasing SVR and cardiac output