Презентация на тему: " Goal of the Cardiovascular System: deliver blood to all parts of the body Does so by using different types of tubing, attached to a pulsatile pump Elastic." — Транскрипт:
Goal of the Cardiovascular System: deliver blood to all parts of the body Does so by using different types of tubing, attached to a pulsatile pump Elastic arteries Muscular arteries Arterioles Capillaries Venuoles Veins Distribution system broken up into areas called vascular beds Skin Digestive (splanchnic) Muscle
Structure of vasculature changes in response to different needs
Why does blood flow through this closed circuit? Blood flows down a pressure gradient The absolute value of the pressure is not important to flow, but the difference in pressure (DP or gradient) is important to determining flow. What happens to pressure if we decrease the volume of a fluid filled compartment (i.e. ventricles during systole)? P directly proportional to F The resulting pressure is called the driving pressure in the vascular system
Even though there are many mechanisms for altering the radius of the vascular system, pressure still drops as blood moves further away from the heart. Why?
Resistance = tendency of the vascular system to oppose flow; Flow = Influenced by: length of the tube (L), radius of the tube (r), and viscosity of the blood ( ) Poiseuilles Law R = L r 4 In a normal human, length of the system is fixed, so blood viscosity and radius of the blood vessels have the largest effects on resistance 1 R
All four tubes have the same driving pressure. Which tube has the greatest flow? The least flow? Why?
Even with a decrease in overall pressure, the pressure in the vessels is not constant. The pressure in the vessels mirrors the pressures generated in the heart – systolic and diastolic pressures. Systolic = ventricles contracting Diastolic = ventricles filling Why does the diastolic pressure rise between the left ventricle and the arteries? Normal blood pressure = 120/80 High blood pressure = 140/90 What could be happening to increase both the diastolic and systolic blood pressure?
Blood Pressure Reflects the driving pressures produced by the ventricles Because arterial pressure is pulsatile, a single value is used to represent the overall driving pressure. This is called the mean arterial pressure. MAP = diastolic P + 1/3(systolic P-diastolic P) Why does diastolic pressure account for a greater proportion of the overall value? SVR = systemic vascular resistance CO = cardiac output SV = stroke volume MAP = Q x R arterioles Explain how these two equations are equivalent