Circulation Flashcards
What are the 2 divisions of the circulatory system?
Pulmonary and systemic circulation
State how much each system contributes to the total circulation
Pulmonary circulation: 9%
Systemic circulation: 84%
Coronary circulation: 7%
List the functional parts of the circulatory system and state the function of each
Arteries: transport blood under high pressure to tissues
Arterioles: control conduits releasing blood into capillaries
Capillaries: exchange fluids, nutrients, electrolytes, hormones, etc
Venules: collect blood from capillaries
Veins: conduits for blood transport from venules back to the heart
Why does the left ventricle have the highest pressure as opposed to the RV?
The pressure in the left ventricle is highest because it has to pump a greater percentage of blood to the entire body, unlike the RV which only pumps blood to the lungs only.
Therefore, the LV has to generate enough pressure to exceed the pressure in the aorta (which is high), in order to pump blood to the aorta and to the rest of the body.
State the basic principles of circulatory function
- Blood flow to most tissues is controlled according to the tissue need
- Cardiac output is the sum of all the local tissue flows
- Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control
What determines blood flow through blood vessels?
Pressure difference: of blood between 2 ends of the vessel (pressure gradient),
Vascular resistance: impediment to blood flow through vessel wall
How is blood flow calculated?
Flow = P2 - P1/Resistance
Explain the different types of blood flow
Blood Flow
Quantity of blood passing particular point in circulation in a given period of time
Laminar flow of Blood in vessels
Blood flowing at a steady rate through a long, smooth blood vessel, it flows in streamlines.
The velocity of flow in the center of the vessel is far greater than that toward the outer edges.
Turbulent flow of Blood in vessels
Blood flowing in all directions in the vessel and continually mixing within the vessel.
What causes turbulent flow in a blood vessel?
When rate of blood flow ↑↑, passes an obstruction in a vessel, makes a sharp turn or passing rough surface; the flow becomes Turbulent.
Define blood pressure and state the normal Bp value
Is the force exerted by the blood against any unit area of the vessel wall. It is measured in millimetres of mercury (mmHg). Resting BP 120/80mmHg
Define resistance to blood flow and write down the formula to calculate.
Is the impediment to blood flow in a vessel. It is calculated indirectly through the measurement of blood flow and the pressure difference between 2 points in the vessel.
R = Change in pressure/ flow
Define total peripheral vascular resistance
The rate of blood flow through circulatory system = rate of blood pumping by the heart (cardiac output);blood flow =100 mL/sec. The pressure difference from systemic arteries to systemic veins = 100 mmHg; therefore, resistance of entire systemic circulation = 100/100, or 1 peripheral resistance unit.
