Cardiology 4: Vascular System Flashcards
what is flow (q)
volume of fluid displaced through a vessel with respect to time (L/min)
flow is determined by what 2 things?
- pressure difference (Pi - Po)
2. resistance (R) across a vessel
resistance is ____ proportional to flow
inversely
pressure difference is ____ proportional to flow
directly
resistance is primarily determined by the ____ of the vessel
radius
a small change in radius results in a ___change in resistance
very large
whenever the radius decreases, the flow decreases to the power of ___
4
what is velocity?
distance fluid travels along a vessel with respect to time
velocity is determined by what 2 things?
- flow through the vessel
2. cross-sectional area of vessel
velocity is ____ proportional to flow
directly
veloccity is ____ proportional to cross sectional area
inversly
as the cross-sectional area increases, the velocity of blood ____
decreases
vasculature plays an active role in regulating ____ and ___ for efficient matching of flow and demand
blood pressure and distribution of flow
each vessel type has a specific function that is determined by its ____
structure
structural feature of arteries
elastic
structural feature of arterioles
can change radius
structural feature of capillaries
material exchange
structural feature of veins
expandable
what is the one common structural feature of all the vasculature of the circulatory system?
a smooth, single-celled layer of endothelium
___ arteries have thick walls with 3 layers
systemic
what are the 3 layers of the systemic arteries?
- intima
- media
- adventitia
describe the structure of the intima
single layer of endothelial cells acting as a metabolically active barrier between blood and the vessel wall
describe the structure of the media
thick layer of elastin and collagen (strength) and vascular smooth muscle (for contraction)
there are 2 main structures of arteries that give them their characteristic functions, what are these structures and their functions?
- large radius: low resistance tubes conductine blood to organs
- elasticity: pressure reservoir for maintaining blood flow during diastole
the arteries store ___ to maintain blood flow during diastole
pressure
what is the function of arterioles?
regulate rate and distribution of blood flow
arterioles are composed of ___ and ____ arranged in rings that allow for vasoconstriction and vasodilation
endothelium and smooth muscle
what are the 2 control systems of the arterioles and what systems control those systems?
- Intrinsic (local conditions surrounding BV control)
2. extrinsic (nervous system input controls)
what are the 3 sources of intrinsic control of blood flow?
- autoregulation / myogenic regulation
- endothelium-mediated regulation
- metabolic regulation
in autoregulation / myoregulation, blood flow is adjusted to _____ based on _____
local pressure; vessel stretch
in autoregulation / myoregulation, changes in local blood pressure cause changes in arteriolar radius and resistance to maintain _____
stable local flow
arterioles ___ with increased local blood flow and ____ with decreased pressure
constrict; dilate
in endothelium mediated regulation, endothelium lining produces substances that ___ or ___ arteriole smooth muscle
relax; contract
give 2 substances that the endothelium produces to induce relaxation of arteriole smooth muscle
nitric oxide; prostacyclin
give 2 examples of substances that the endothelium produces to induce contraction of the ateriole smooth muscle
angiotensin 2 and endothelin