Systemic and Arterial Blood Pressure (Nursing)

00:01 So now let's look at the different pressures throughout the body.

00:04 Starting with systemic blood pressure.

00:07 So the pumping action of the heart is going to generate our blood flow.

00:12 The pressure results when the flow is opposed by the resistance in our vessels.

00:17 Our systemic pressure is going to be highest at the aorta.

00:22 And as the blood flows throughout our system, it's going to decline throughout the pathway.

00:28 The steepest drop of systemic pressure is going to happen we move into the arterioles.

00:35 So as you can see in the graph, blood pressure is highest in the largest vessels beginning at the aorta and leaving the heart.

00:43 As the diameter of the vessels decrease and move further away from the aorta, the pressure decreases.

00:51 Once the blood passes through the capillaries and goes to the veins, the pressure is very low.

00:59 This is why our venous system is considered a low pressure system.

01:05 So now let's look at the different types of blood pressure.

01:08 Starting with arterial blood pressure.

01:11 Our arterial blood pressure or the blood pressure in our arteries is determined by two factors: First, the elasticity of the artery, especially of the arteries close to the heart.

01:25 This is referred to as compliance or the distensibility of our arteries.

01:31 Second, the volume of the blood that is forced into the arteries at any given time.

01:39 So the blood pressure nearest to the heart is pulsatile.

01:43 It's going to rise and fall with each heartbeat.

01:48 So we measure the arterial blood pressure using two parameters.

01:53 The systolic pressure is going to be the pressure that is exerted in the aorta during a ventricular contraction.

02:01 The left ventricle is going to pump blood into the aorta, and this is going to impart a kinetic energy that causes the aorta to stretch.

02:11 The average systolic pressure is about 120 mm Hg in a normal adult.

02:18 The second parameter is our diastolic pressure.

02:21 This is going to be the lowest level of aortic pressure when the heart is in diastole or at rest.

02:30 We also have the pulse pressure.

02:32 The pulse pressure is measured as the difference between the systolic and the diastolic pressure.

02:39 Our pulse is going to be the throbbing of our arteries due to the difference in the pulse pressures, which can be felt under our skin.

02:50 We can also measure the mean arterial pressure, which is the pressure that propels our blood to our tissues.

02:58 The pulse pressure phases out as we get to the end of the arterial tree, and flow becomes nonpulsatile with a steady mean arterial pressure, the further away we get from the heart.

03:13 Our heart is going to spend more time in diastole than it does in systole.

03:18 So our mean arterial pressure cannot just be simply an average of the diastole to the systole.

03:27 We measure our mean arterial pressure by adding the diastolic pressure to 1/3 of the pulse pressure.

03:35 Where if you recall, the pulse pressure is equal to the systolic minus the diastolic pressure.

03:42 So for example, if an individual has a blood pressure of 120/80, where 120 is the systolic pressure and 80 is the diastolic pressure, then the pulse pressure is going to be 40.

03:57 And the mean arterial pressure will be measured as 80 + 1/3 of 40, which gives you about 93 mm Hg.

04:08 Note, that the pulse pressure and the mean arterial pressure are both going to decline with increasing distance from the heart.