Chapter 10 - blood pressure Flashcards
F =
flow rate of blood through a vessel
flow rate through a vessel is _________ to the pressure gradient and ________ to vascular resistance
directly proportional
inversely related
delta P
pressure gradient difference
- the higher the delta P, the greater the F
R =
resistance of blood vessels
- resistance is a measure of opposition of blood flow through a vessel
three things that oppose flow of blood
blood viscosity
vessel length
vessel radius
major determinant of resistance to flow is _______
vessel’s radius
slight change in radius produces significant change in ______
blood flow
arteries
carry blood away from heart to tissues
- specialized to serve as rapid-transit passageways for blood from heart to organs
3 layers of arteries
tunica interna (inner - endothelium) tunica media tunica externa - outer
arterial connective tissue contains: collagen fibers
provides tensile strength
arterial connective tissue contains: elastin fibers
provide elasticity to arterial walls/compliance (rubber band bounce into shape analogy)
due to large radius, arteries offer little ______ to blood flow
resistance
arteries act as ________ to provide driving force for blood when heart is relaxing
pressure resovoir
aterioles defined
smaller branches of arteries - deliver blood to organs
arterioles: major ______ - due to smaller radius
resistance vessels
vasoconstriction
narrowing of vessel/decrease radius
- smooth muscle (tunica media) contracts
- increase resistance
- decrease flow
vasodilation
increase in vessel radius
- smooth muscle relaxes
- decrease resistance
- increase flow
only blood supply to ______ remains constant
brain
control of diameter: local metabolic changes
- higher metabolic activity = higher blood flow
- lower metabolic activity = lower blood flow
- vasodilate in response to: decrease O2, increase CO2, increase acid, increase K+, increase adenosine
control of diameter: local vasoactive mediators
- endothelial cells release vasoactive paracrines to affect arteriole radius
- NO reduces intracellular Ca+ concentration in smooth muscle = vasodilation
control of diameter: local physical influences on arteriolar radius
local application of heat and cold
- prevent swelling = cold
- opening up blood flow = hot
- shear stress - NO release
control of diameter: sympathetic stimulation
- s.m. of arterioles richly innervated
- alpha 1 = excitatory
- increase activity = vasoconstrict
- decrease activity = vasodilate
- establishes vascular tone
- regulate flow into organs and MAP
- establishes vascular tone
control of diameter: histamine
vasodilation
control of diameter: angiotension II
potent vasoconstrictor
vascular tone
reflects the state of partial s.m. contraction to establish baseline resistance
- ex. severely allergic people to bee stings lose their vascular tone
MAP = overall ____
BP
