systolic and diastolic_ Physiology class.pptx

Systolic and diastolic blood pressure

1. Arterial Blood pressure

2. Arterial Blood pressure Generally, the termed ‘blood pressure’. Arterial blood pressure is defined as the lateral pressure exerted by the column of blood on wall of arteries. It is the pressure is exerted when blood flows through the arteries.

3. Expressions of Arterial pressure Systolic blood pressure is defined as the maximum pressure exerted in the arteries during systole. Normal systolic pressure: 120 mm Hg (110 mm Hg to 140 mm Hg). Diastolic blood pressure is defined as the minimum pressure exerted in the arteries during diastole . Normal diastolic pressure: 80 mm Hg (60 mm Hg to 80 mm Hg). Pulse pressure is the difference between the systolic pressure and diastolic pressure. Normal pulse pressure: 40 mm Hg (120 – 80 = 40) Mean arterial blood pressure is the average pressure existing in the arteries. Note: It is not the arithmetic mean of systolic and diastolic pressures. It is the diastolic pressure plus one third of pulse pressure.

4. Mean arterial Pressure calculation Formula to calculate mean arterial blood pressure: Mean arterial blood pressure = Diastolic pressure + 1/3 of pulse pressure Example 80+40/3= 93.3 mm Hg

5. Variations of Arterial Blood pressure Arterial Blood pressure is altered under certain physiological and pathological conditions,some physiological varations include: Age. After meal Body build. During sleep Sex. After excercise Pathological variations include Hypertension and hypotension.

6. Factors that maintain arterial Blood pressure This refers to factors necessary for the maintenance of blood pressure .These factors are either local or mechanical. The types of local factors include Central factors- referring to the heart Peripheral factors- referring to blood and blood vessels.

7. Central factors Cardiac Output: Systolic pressure is directly proportional to cardiac output. Whenever the cardiac output increases, the systolic pressure is increased and when cardiac output is less, the systolic pressure is reduced. Cardiac output increases in muscular exercise, emotional conditions, etc. So in these conditions, the systolic pressure is increased. In conditions like myocardial infarction, the cardiac output decreases causing fall in systolic pressure. Heart Rate Moderate changes in heart rate do not affect arterial blood pressure much.however in significant changes in heart rate affect the blood pressure by altering cardiac output

8. Peripheral factors Blood volume -Blood pressure is directly proportional to blood volume. Blood volume maintains the blood pressure through the venous return and cardiac output. If the blood volume increases, there is an increase in venous return and cardiac output, resulting in elevation of blood pressure Peripheral resistance : is the most important factor, which maintains diastolic pressure. Diastolic pressure is directly proportional to peripheral resistance. Peripheral resistance is the resistance offered to the blood flow at the periphery. Resistance is offered at arterioles, which are called the resistant vessels. When peripheral resistance increases, diastolic pressure is increased and when peripheral resistance decreases, the diastolic pressure is decreased.