Phys: The Heart As A Pump Flashcards
(103 cards)
**just fyi…know the circuit of the heart pump and flow
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What is constant in normal intact circulation?
Total blood volume
An increase in the volume of blood in one area must be accompanied by what..?
A decrease in blood volume in another area
What determines the distribution of blood circulating to the different regions of the body?
-output of the left ventricle
-the contractile state of the resistance vessels (arterioles)
Blood vessels serve as a ________system of passive conduits that delivers blood to and from the tissue
Closed
Blood vessels participate ___________ in the regulation of blood flow to the organs.
Actively
What happens when resistance in the blood vessels (particularly arterioles) is altered?
Blood flow to that organ is altered
The aorta is made up of primarily what tissue?
Elastic tissue
What are the most muscular vessels?
Arterioles
In the large arteries, frictional resistance is relatively _______ and pressures are _______________ than those in the aorta
Small, slightly less
Maximum resistance of blood flow occurs in which vessels?
Arterioles
Where in the vessels is pressure drop the greatest?
The terminal segment of small arteries and arterioles
Is capillary blood flow pulsatile or non-pulsatile?
Non-pulsatile
What progressively dampens pulsatile pressure?
-elasticity of arterial walls
-frictional resistance of small arteries and arterioles
Characteristics of arteries:
-thick walled
-elastic
-highest pressure
Characteristics of arterioles:
-smooth muscle
-highest resistance to blood flow
-alpha 1 receptors
-beta 2 receptors
What does alpha 1 cause in the arterioles?
Contraction or constriction of the vascular smooth muscle
What does beta 2 cause in the arterioles?
Cause dilation or relaxation of vessels in the skeletal muscle
How do arterioles change resistance in the vessels?
Through sympathetic nerve activity via Catecholamines and other vasoactive substances
What is the structure of capillaries?
Thin-walled and lined with a single layer of endothelial cells
Where does the greatest pressure drop occur?
Arterioles
What occurs in the capillaries?
-gas exchange
-is a site for nutrients
Characteristics of veins and venules:
-thin-walled
-endothelial cells layer
-modest amount of elastic tissue, smooth muscle, and skeletal muscle
-large capacitance
-alpha 1 receptors
What is cardiac output?
The rate at which blood is pumped from either ventricle