L15 Systemic Circulation I Flashcards
Elastin, Smooth m., collagen in vessel wall
Elastin: in Arteries only. High compliance (elastic is stretchy)
Smooth muscle: in both arteries and veins, but more in arteries
Collagen: mainly in veins; Low compliance makes vein stiff to withstand high pressures
Pulse Pressure profiles in circulatory system
Pressure Pulse shows the Systolic and Diastolic Pressures for phases in the circulatory system
Pulse Pressure = SP - DP —> 120-80 = 40mmHg
LV - 0-120mmHg
Aorta - 90-120mmHg (dichrotic notch keeps DP at 90)
artery - 80-130mmHg (Pulse Pressure begins to widen)
arteriole - LARGEST P DROP 50-100mmHg
capillaries and veins have NO PULSE PRESSURE bc blood is constantly flowing
Mean Arterial Pressure decreases as you get away from the Heart; this drives the blood forward
High Pulse Pressure = bad because it’s an afterload on the heart and can cause damage in long term
Compliance
The propensity to change volume with pressure change
Low compliant vessel like an artery is more stiff and doesn’t just open. This vessel would have higher arterial pressure because a slight change in velocity would cause a large P change
High compliance veins easily stretch, which reduces their P.
Continuous capillary
BL and endothelium is continuous
tight junctions
in muscle and connective tissue
Fenestrated capillaries
F for filtering
BL and endothelium is continuous but has some holes
can have diaphragms (used for filtering)
used by kidney and intestine
Discontinuous capillaries
lots of big holes in endothelium and BL
liver, bone marrow, spleen —- things that pass large substances
Windkissel property of the aorta
The closing of the aortic valve and subsequent recoil of the aortic wall is like a secondary pump that pushes blood forward, this second pushing of the blood is the DP.
With a very low compliant aorta, that is stiff, this recoil doesn’t happen and it allows the DP to just die off instead of giving it a boost
Pressure Pulse
This is the radial pulse you can feel at the wrist.
This pulse is created by an energy wave created by pumping of blood that travels through the VESSEL WALL at 5-15 m/s (BF = 1m/s)
A low compliant/stiff vessel will not carry energy as well and therefore the velocity of propagation increases. (energy travels better through stiff things than non-stiff things)
Related to Pulse Pressure
Pulse Pressure vs. Pressure Pulse
Pulse Pressure: ~blood pressure —- the difference b/t SP and DP
Pressure Pulse: the pulse that a pressure wave creates in vessel walls
