B3W3 Trans Phys Regulation of flow Flashcards
Distribution Vessels
Conductance vessels or arteries
Diffusion/filtration vessels
capillaries
Resistance vessels
arterioles and venules
Microcirculation
arterioles, capillaries, and venules
Collection vessels
Capacitance Vessels or Veins
Blood pressure and volume distribution
Blood pressure is higher arterially than venously but increases in volume on the venous side
Pulse Pressure
Difference between systolic and diastolic pressure in an artery (SBP-DBP)
Determined by stroke volume and vessel compliance V/P
High Pulse Pressure
Atherosclerotic disease or rigid arteries
Low pulse pressure
hypothyroidism reduced CO or low SV
Perfusion pressure
Change in pressure from arterial side to venous side
Determinants of Perfusion pressure
Vasoconstriction and vasodilation of small vessels, mainly arterioles and venules, which regulate blood pressure and flow
Flow equations
Flow = velocity x cross sectional area
Flow = pressure / resistance
Local Vasodilators
Nitric Oxide
Hydrogen Ions
Adenosine
Prostaglandins
Local Vasoconstrictors
Endothelin
Oxygen
Area Vs. Blood velocity
High Area = Lower Blood Velocity but same flow due to cross sectional area
Pressure Volume Distribution
As the Mean Pressure decreases Percent Volume increases, until the vena cava
Elastance Vs. Compliance
Elastance is ability to bounce back to original shape
Compliance is how easy it is to change the shape
Vein and Artery Compliance and Elastance
Artery High Elastance Low Compliance
Vein Low Elastance High Compliance
Contraction of Smooth Muscle
Calcium in -> Calcium release from SR -> Ca with Calmodulin -> Calcium with calmodulin activates MLCK -> MLCK phosphorylates MLC into p-MLC to increase contraction
Relaxation of Smooth Muscle
cAMP inhibits MLCK
cGMP activates PKG which inhibits activated MLCK
cGMP also inhibits l type calcium channel
