24th lecture (vascular pathogogy) Flashcards
the complications for atherosclerosis is? 4
- aneurism
- rupture
- thrombosis
- critical narrowing
sometimes endothelial damage can lead to enlargement of the of the vessel
A special note about where the nutrition for blood vessels is coming from?
its coming from the adventitial side of the vessels, which contain lots of small vessels. The larger vessels have many more cells.
Capillary endothelial cells and pericytes get their oxygen from the lumen of the vessels, and large veins also do too.
what happens during endothelial cell injury?
The surround cells and structures will detect the components of the blood as foreign material and thus a recruitemtn of certain types of mesenthymial cells to build up a wall against the foreign material to protect structures outside of the vessel.
Thus we can see more and more thickened material in the vessel wall, as vessels thicken.
what is the problem with excessive endothelial damage that causes vessels to thicken?
the vessels thicken to such an extent that the blood cannot flow well enough for the organ to survive as the vessel lumen is narrowed. Hypertension could occur. The hypertension could cause further endothelial damage and this increases the amount of connective tissue in the vessel wall causing the positive feedback loop.
what material builds up the structure of vessels during injury?
with elastic staining we can see that not only cell but other connective tissue elements such as multiple layers of elastic fibers. The elastic fibers will not be degraded as fast as they are built up and thus accumulation of elastic can be seen in hypertension.
In small vessels only few nuceli is seen. there is a material that accumulates under the endothelial cells will contain a lot of collagen, glycoaminoglycans, is seen as a homogeneous layer with HE stain.
This can disturb the function of the smooth muscle cells. Do to the damage of the endothelial cells material can leave the vessel into the interstitial spaces.
what happens to capillaries that are damaged?
capillaries should have very flat endothelial cells with no visible cytoplasm. But in a damages state the endothelial cells will have enlarged cell nuclei and inflammatory cells can also be seen which can disturb the endothelial cells homeostasis.
Describe atherosclerosis?
under endothelial cells a collection of cell, necrotic material are visible.
Macrophages will accumulate later on along with lipids, inflammation can take place as well.
an almost unlimited inflammation can take place here. The main goal is to separate the accumulated materiel from the other structures, which is why we will have fibrous cap structure around the plaque.
This is a protective process.
describe the process of atherosclerosis plaque formation?
- endothelial injury (hypertension, virus, toxins)
- endothelial dysfunction (material leaves the vessels)
- Macrophages activate and smooth muscle is recruited.
- macrophages and smooth muscle cells engulf lipid
- smooth muscle cell proliferation, collagen and other ECM deposition.
what do we see in the beginning state of atherosclerosis plaque formation?
-fatty streaks (these start forming from birth) the plaques can become calcified.
In more advanced state multiple thrombi can form upon ulceration.
what can cause the enlargement of vessel during the formation of plaques or damage?
The enlargement could be caused by a weak point that cause a:
small bubble like enlargement: saccular aneurysm
longitudinal symmetrical aneurysm: fusifrom aneurysm
This can form in both small and large vessels too.
what could happen if a vessel ruptures?
the rupture could close up do to additional material around the vessels or only the inner layers of the vessels may be affected causing bleeding along the vessels between the layers.
The biggest problems are the aneurysm of the circle of willus in the brain (1 of 20 people have a problem with these vessels. Since these aneurysms cannot be detected by physical examinations. If the aneurysms can lead to symptoms, but they can also lead to inter-cranial bleeding.
The endoscopical procedure to fix this: fill up the lumen of the aneurysms with collagen rich material. A small metal clip can be used to close the aneurysms. Normally the arteries should be blue showing that the vessel is thin and filled up with blood, if its yellow it a plaque.
enlarged aneurysms can push on the brain.
traumatic brain injury in boxing and sports can cause the problems of vascular injury and then ruptures and then neuron death in the brain.
how do we fix a dilated aorta?
we can place a stent in the dilated aorta. Idealy the blood should go through stent. The “empty” area between the stent and the aorta wall will be filled up with coagulated blood as some RBC can make their way into the area and coagulate do to the lack of laminar flow.
the thrombus can support the stent. Eventually granulation tissue will form and eventually the thrombi will become very hard tissue to support the stent.
Other times an artificial vessel can replace a section of the aorta in an open chest surgery. The rest of the aorta they use as an outer surface of the vessel which minimizes the immunological reaction.
Note what happens during aortic rupture and what types of ruptures exist?
Death of the patient could occur withing seconds.
Different ruptures require different surgerys
-Debakey I: the entire aorta is affected.
-Debakey II: ascending aorta
-Debakey III: the descending aorta is ruptures and a large section may need replacement.
- 1 and 2 are type A
- 3 is type B
Why is debakey I so dangerous? its not only the blood loss but also the narrowing of the vessels leading to the brain and renal gland, causes necrosis of the internal organs.
under the microscope what disturbance can be seen in vascular layers?
elastic fibers show disturbances of the basic structure such as:
-enlargement of the laminar layers of the elastic fibers. The background could be genetic and mutations, TGF-B mutation could be one, but many exist.
hypercholesterolemia can also cause damage.
when blood is found in the body cavity what does the color indicate?
dark = coagulated
Bright red = fresh
