Vasculature Flashcards
what purpose do blood vessels serve in the cardiovascular system?
serve as a pathway for blood to travel from one part of the body to another
Blood flow =
Pressure gradient/resistance
PRESSURE GRADIENT
refers to the difference in pressure between one spot and another
the greater the pressure gradient, the greater the blood flow
RESISTANCE
refers to anything that would hinder blood flow
Primary factor that could affect resistance
VESSEL DIAMETER/WIDTH - changes regularly
blood viscosity and vessel length also affect resistance
VESSEL WIDTH is REGULARLY CHANGED to
REDIRECT BLOOD FLOW FROM ONE ORGAN TO ANOTHER
OR
TO MAINTAIN ADEQUATE BLOOD PRESSURE
VASOCONSTRICTION
involves smooth muscles in the vessel wall contracting and narrowing the vessel
VASODILATIONS
refers to the smooth muscle relaxing and widening (dilating) the vessel
Know intrinsic and extrinsic vasocontrictors and vasodilators?
ARTERIES lead away from heart chambers, branching into
small arteries known as ARTERIOLES
ARTERIOLES branch into _____, where ___________ take place
CAPILLARIES;
where exchanges between the blood and the tissues take place
VEINS lead back towards heart chambers, beginning as
small veins, knowns as VENULES, formed by the merging of capillaries and leading to large veins near the heart
Tunica interna
inner lining of the vessel, in direct contact with the blood in the LUMEN
What varies from one type of vessel to another
the presence, composition, and thickness of the walls
LARGEST ARTERIES
have less smooth muscle and MORE ELASTIC TISSUE in the tunica media, which allows them to STRETCH AND THEN RECOIL
MEDIUM, MUSCULAR ARTERIES - tunica media
contains more SMOOTH MUSCLE fibers, less elastic tissue
functions of medium, muscular arteries
DISTRIBUTE BLOOD (GENERAL) VIA VASOCONSTRICTION/DILATION
functions of ARTERIOLES
notable sites for VASOCONSTRICTION AND VASODILATION
greatest influence on BLOOD PRESSURE
determine SPECIFIC CARDIAC OUTPUT DISTRIBUTION (along with smaller arteries)
CAPILLARY WALLS
single layer of endothelial cells
capillaries may have ____ between the cells
PORES (FENESTRATIONS)
function of pores
EXCHANGE of substances between blood and tissues
function of venules
RETURN BLOOD TO LARGER VEINS
two kinds of VENULES
- POSTCAPILLARY VENULES
- MUSCULAR VENULES
POSTCAPILLARY VENULES
smallest venules
form when several capillaries unite
walls are very porous serve as the site for WBC emigration
