Lesson 2C Part2 Flashcards
Capillary bed consists of
Aterioles, capillaries and venules
Each beat of the heat proppels ___cc of blood from ventricle into the arterial tree
70
Why must the hearts output be stored during systole
The capillary network cant keep up
Each beat pumps approx ____ml of blood into aterial system
70ml
Each minute approx ___ liters of blood is ejected
5 litres
Even though the mean pressure gradually declines past the resistance vessel
The systolic portion of the pressure wave actually increase
Why does systolic portion of pressure wave go up after resistant vesses
This phenomenon is due to increasing stiffness of the vessel walls toward the periphery and the reflected waves which are enhanced by increasing peripheral resistance
In the circulatory system there are
High pressure, high energy arterial reseviour
Low pressure, low energy venous pool
During diastole, energy stored in
The stretched elastic walls of the arteries
Sotred elastic energy is used to
Propel blood forward through the peripheral resistance vessels
The pressure is highest during ____ and lowest during
Highest during ventricular systole and lowest during ventricular diastole
Normla patient blood pressure
120/80
Systolic/diastolic
Aortic pressure
120mmHg
Vena cava blood pressure
4mmHg
how is energy lost in circulation? In the form of _____
Heat
The resistance offered by the peripheral circulation is known as
Systemic vascular resistance
The main resistance vessels are
Arterioles
Simple flow model
An increase in resistance in a large distributing artery because of atheroma must be compensated by a decrease in the resistance of the small arteries and arterioles
The compensation of dilation by arterioles eventually results in
Reduction of flow to organs and ischemia because no further dialation is possible. Any increase in the degree of stenosis leads to a reduction in flow
Why are the arterioles considered autoregulatory
They dynamically change in diameter to increase or decrease flow
Happens during exercise
3 sources of peripheral resistance
Blood viscosity
Blood vessel diameter
Total vessel length
Viscosity determines (4)
Friction against vessel walls
Rate of venous return
Work required to pump the heart
How much oxygen is transported to tissues and organs
Hemoconcentrated blood will flow
More steadily (higher velocity)
What is hematocrit
The percentage of red blood cells in the total blood volume
Hematocrit increases when
There are more red blood cells OR if there is less plasma
Doubling the hematocrit does what to the viscosity
More than doubles
Polycythemia is what
A condition of abnormal elevation in red cell hematocrit causing higher blood viscosity
Anemia causes
Low hematocrit and reduced blood viscosity
