Vasculature (L17) Flashcards
Define the Laplace relationship
This is the force necessary in the vessel wall to oppose rupture. We can think of this as wall tension. This tension is equal to the pressure in the vessel multiplied by the radius, divided by the wall thickness. Thus small vessels with thick walls will have the smallest force necessary to oppose rupture.
Relationship between Laplace’s relationship and anyeurisms
An anyeurism is a thinning and bulging of a vessel wall. This means that it would need to overcome a relatively larger amount of pressure to avoid bursting.
Compliance
Opposite of vessel stiffness
The amount of pressure a vessel generates is inversely proportional to the compliance. If something has lower compliance, it can’t bend as much and generates more pressure.
Broadly speaking, what are the 3 layers of vessels (innermost to outermost)
Tunica intima, tunica media (media) , tunica adventitia (adventitia)
When we think about arteries what is the composition of the tunica intima?
Single layer of endothelial cells, a sub-endothelial layer, and an elastic laminae. This is stretchy and works like a spring (highly compliant)
Tunica media in arteries
very thick layer of smooth muscle (NOT compliant), which allows vessels to vasoconstrict. Another elastic laminae is also present on top of the smooth muscle layer.
Tunica adventitia in arteries
Layer of collagen and fibroblasts, this is pound-for-pound stronger than steel. However, this layer in arteries is smaller than that in veins.
Tunica intima in veins
Endothelium and sub-endothelial layer (NO elastic laminae in this layer)
Tunica media in veins
A thin layer of smooth muscle (once again, there is no elastic laminae here)
Tunica adventitia in veins
A thick layer of collagen and fibroblasts
What are vaso vassorum?
The vaso vassorum are the vessels that feed vessels. basically, to get smooth muscles to contract, you’re going to need to provide them with energy. So there are little vessels that kind of reach in there and feed them.
Veins have (what kind of compliance). This means they can serve (what purpose with regard to blood volume)?
Veins have high compliance because they are never filled. This means they can serve as capacitance vessels and can act as a “storage” of blood (although blood is never stagnant)
arteries have (what kind of compliance). Therefore, with regard to their physiological purpose, they are considered (what kind of vessels)
Low compliance; they are filled up. They are considered resistance vessels.
Label the parts of this vessel and name what it is
This is a transverse section of a large elastic artery.
A: Internal elastic laminae
B: Tunica media (squiggles are the elastin in this layer )
C: Tunica adventitia
D: Endothelium
E: Small blood vessels
Label the parts of this vessel and say what it is
This is a medium caliber (muscular ) artery
A: Endothelium
B: Internal elastic laminae
C: Tunica media (showing darkly stained smooth muscle cells)
D: Tunica adventitia
E: Small vessels feeding big vessel
Name parts of this histology diagram and vessel types shown
A: Adipose tissue
B: Small artery
C: Capillaries
D: Small vein (you can tell by how thin it is & The fact that it is not filled all the way)
Name the parts of this vessel and its type
This is a cross-section small arteries.
A: Internal elastic laminae (Squiggles)
B: tunica media (smooth muscle)
C: Adventitia
D: Internal elastic laminae (squiggles)
E: Tunica media (smooth muscle)
name vascular structures in image
Small arteries and venules
A: Lymphatic system
B: Venules
C: Arterioles (VERY thick walls)
How does the aorta behave like a hydraulic (Windkessel) filter?
The aorta is compliant because of those elastin fibers. Thus, when blood is pumped in, the aorta will stretch. This stretch means you have a larger container for the same amount of fluid, which means this is a lower pressure on the system. However, the elastin will store the energy in the form of potential energy (pressure). If you’re lacking in compliance no pressure energy can be stored which means it’s harder to squeeze stuff down.
Age-related compliance of aorta
As you age, the compliance (stretchiness) of your aorta decreases, which can lead to hypertenisve outcomes. This can lead to an increased risk of LV heart failure. This is because elastin is slowly replaced by collagen which is very stiff
This can be mitigated by exercise but not reversed by exercise.
Continuous capillaries
No holes
Good for gas and nutrient exchange, but only if that thing can easily travel with water (so not like large lipids or proteins)
Most common
Fenestrated capillaries
has some small holes but is more or less continuous capillary; this is the kind of vessel in for instance glomerular areas. This allows for bigger nutrients to move in and out with more ease and not just very small electrolytes. This is not only in renal but enteric systems.
Discontinuous capillary
This is a capillary with BIG BOY holes. This is when you’d want to be able to get a WHOLE ASS CELL in and out of there. For instance, in bone marrow and spleen. Or by the liver where you synthesize a lot of proteins like albumin for plasma.
What is this vessel and what are the arrows pointing to?
This is a transverse section of a continuous capillary (no visible holes). The arrows are pointing to little blebs that are pinocytotic vesicles being released into it.
What is this vessel type. What are the arrows?
Transverse section of a fenestrated capillary.
Arrows are indicating the fenestrations (small holes) that are allowing for better exchange of nutriens.
What are pulse pressure and pressure pulse?
Pressure pulse is the measurement of pulse pressure.
Pulse pressure is the aortic vs diastolic blood pressure (so for instance, pulse pressure of smeone who was 120/80 would be 40).
Now, When you inject blood into the aorta it creates a pressure wave. This is like a sound wave and moves very fast, faster than the flow of blood. The pulse pressure is the measurement of that sound wave’s movement. Therefore, if you’re comparing pulse pressure times at location A in the arm vs location B in the leg, which are distant from one another, this difference will give you the pressure pulse, which can give you an idea of how stiff the arteries are because a stiffer artery is less compliant and will mean this sound wave will travel slower.
There is some normal stiffening of arteries in pregnancy that can increase the time associated with pressure pulse. I hate pregnancy.
