Day 2: Cardiovascular System Objectives Explain the meaning of blood pressure Explain the relationship between blood pressure and arterial pressure. Describe what happens to pressure has it travels through the many blood vessels. Explain how Blood Pressure is measured using a simple mathematical equation

Day 2: Cardiovascular System What do we mean by blood pressure? Home Page Day 2: Cardiovascular System What do we mean by blood pressure? Hydrostatic pressure because blood is fluid ARTERIES ARTERIOLES CAPILIARIES HEART Because blood is being pumped, it will exert pressure on the blood vessels As blood travels through the blood vessels, it’s hitting against the inner walls of these vessels This exert a pressure on the blood vessels ….called BLOOD PRESSURE Heart beat send blood out to the body via blood vessels

Day 2: Cardiovascular System Factors Affecting Blood Flow Home Page Day 2: Cardiovascular System Factors Affecting Blood Flow Peripheral Resistance is the opposition to blood flow It affects mainly arterioles because arterioles have thin flexible-extendable walls. Arterioles walls can constrict or dilate causing peripheral resistance Link to Arterioles diagram CROSS-SECTION OF ARTERIOLES Dilated walls Constrict walls Point out to students the main function of the circulatory system: 1. obtain and distribute oxygen = P.R = P.R Low blood pressure High blood pressure

Day 2: Cardiovascular System Relationship between P.R. and B.P. Vaso-constriction and dilation of Arterial wall Smaller the diameter of arterial wall, the greater the Peripheral Resistance ( opposition to blood flow). The more resistance to blood flow, the greater the pressure needed to move blood through the arterial vessels. High Peripheral Resistance = High blood Pressure Small diameter wall Low Peripheral Resistance = Low Blood Pressure Large diameter wall

Day 2: Cardiovascular System How do we measure blood pressure Home Page Day 2: Cardiovascular System How do we measure blood pressure HEART VEINS-vena cava Aorta-ARTERIES ARTERIOLES VENULES Exchange of materials through diffusion CAPILIARIES CAPILIARIES If the arrows indicate blood flow and the size of the arrows indicate pressure, where is pressure greatest in this simple blood flow diagram? Explain what happens to pressure as blood travels from the heart to the body and from the body back to the heart. 5

Day 2: Cardiovascular System Check your understanding Blood Pressure is really a measure of Arterial pressure We can replace blood pressure with arterial pressure So… Arterial Pressure = Peripheral Resistance High Arterial Pressure = High Peripheral Resistance Low Arterial Pressure = Low Peripheral Resistance

Less pressure on Arterial wall Day 2: Cardiovascular System Cardiac Output (C.O.) Define Cardiac Output: The measure of how much blood is pumped out from the heart. Or Heart Rate. Take a moment and let’s measure your heart rate… List some factors that can increase your heart rate or cardiac output A HEART B HEART Low Cardiac Output High Cardiac Output Less pressure on Arterial wall More pressure on Arterial wall High Blood Pressure Low Blood Pressure

Day 2: Cardiovascular System Formula for calculating Blood presure (Arterial Pressure) Blood Pressure = Peripheral Resistance High Peripheral Resistance = High Arterial Pressure Low Peripheral Resistance = Low Arterial Pressure (Arterial Pressure) Blood Pressure = Cardiac Output High Cardiac output = High Arterial Pressure Low Cardiac output = Low Arterial Pressure (Arterial Pressure) B.P. = Peripheral Resistance X Cardiac output

Day 2: Cardiovascular System Factors Affecting Blood Flow Home Page Day 2: Cardiovascular System Factors Affecting Blood Flow Factors affecting blood flow Peripheral Resistance Blood Vessel Diameter Blood viscosity Total Vessel Length Cardiac Output These modules are design to link to other PowerPoint that further emphasize each point, either through an in class activity or a PowerPoint diagram . The cardiac output module is design with a specific activity that may take a few minutes to conduct in class. This can be done as a simple demonstration to illustrate how cardiac output increases blood flow, thereby increasing blood pressure. The bulk of the class period will be spent working on a heart model.

Blood viscosity is the measure of thickness of blood. Return to Module Slide Blood Viscosity If blood viscosity increases with added RBC, which item you think would have the most concentration of RBC? Blood viscosity is the measure of thickness of blood. Blood consist of 4 components: RBC, WBC, PLATELETS AND PLASMA RBC is the largest of the blood components More RBC means more thickness Less RBC means less thickness

More mass means more blood Vessels needed to cover Return to Module Slide Blood Vessel Length Total Blood Vessel Length Longer the blood vessel, the longer it will take for blood to travel and the greater the pressure needed to push blood through Obesity adds to overall total vessel length. gain 2.2lbs = gain 400 miles of b.v. 1 k.g. = 650 km of B.V. More mass means more blood Vessels needed to cover

Blood vessel diameter: Return to Module Slide Blood Vessel Diameter Blood vessel diameter: Anything that vasoconstrict blood vessels will increase P.R. Anything that will vasodilate blood vessels will decrease P.R.