Cardiovascular Pathology: Overview Flashcards
Atherosclerosis is
a Pathological change in the wall of the artery.
Number 1 cause of death in Canada is:
Atherosclerosis, responsible for MI, stroke, aneurysm, peripheral vascular disease)
Tunica intima:
layer of endothelial cells
Tunica media:
smooth muscle
Tunica externa:
connective tissues
Fatty streak is:
universal lipid accumulation in proliferating intima. Occur almost to everyone over 20.
Fibrous tissue accumulate in the intima is called
atherosclerosis (Abnormal)
Major clinical Manifestations of Atherosclerosis:
- Usually asymptomatique
- Angina
- MI
- Transient Ischemic Attack
- Ischemic stroke
- Peripheral Arterial Disease
Angina vs MI:
Angina: partially occluded the coronary artery, when there is activity, increase demand in supply but cannot meet the demand on O2.
MI: Completely occluded, pain is more severe.
Transient Ischemic Attack vs Ischemic stroke:
TIA: partially occluded the vessel in the brain.
Ischemic stroke: completely occluded in the brain.
Peripheral Arterial Disease:
not enough blood flow to the legs causing intermittent claudication. During activity, blood flow to the legs become inadequate and they will experience pain. As it progress, pain can be experienced at rest.
Key components of the pathogenesis of Atherosclerosis:
Endothelial dysfunction
Chronic Inflammation
Damage to the endothelium due to:
- Hyperlipidemia
- Hypertension (physical injury)
- Smoking (7000+ compounds, some damage the endothelium)
Damage to the endothelium cause the cell to become dysfunctional or altered:
- Increase permeability
- Platelets and lymphocytes release mediators (Platelets release PDGF and lymphocyte release IL-1 and IFN)
- Monocytes release MDGF as they migrate into the tunica media vessel wall (do not belong there) and become macrophages
- Fibroblasts and smooth muscles cells get involved and release other mediators (eg. growth factors)
Which region of the vessel, the endothelium is more vulnerable to hemodynamic stress (Hypertension)?
The branch point, at the bifurcation.
Which region of the vessel, the endothelium is more vulnerable to developing plaque?
The branch point, at the bifurcation.
Inflammatory component of atherosclerosis: involve T-cells and Macrophages
- Monocytes migrate into the wall of the vessel, particles of LDL are able to access the inner wall, which damage the endothelium.
- Inside the wall of the vessels, macrophages (have a specific receptor for LDL) swallow a lot of LDL and becomes a foam cell.
- Release of cytokine and free radical
- Necrosis in the middle of the plaque starts to form as these are accumulating and a fibrous cap is formed (create an extracellular matrix)
- Inflammation in the vessel wall, the smooth muscle cells become involved and start proliferating in direction of the tunica intima due to signaling molecules. (mitosis)
- Smooth muscles cells change properties (accumulate lipid, become foam cells, synthesize collagen, elastin and glycoprotein)
- Lymphocytes get involve too, a fatty streak is developed and get bigger and bigger.
Lipoproteins role:
Allows the transportation of lipid in an aqueous medium (eg. blood)
Lipoprotein component:
Inside the lipoprotein (triglycerides and cholesterol)
On the surface (Apo proteins and phospholipids)
Accumulation of lipoprotein:
- Protein on the surface are distrinctive (allow different cells to recognize the different lipoproteins and take them in)
- Lipoprotein are absorbed in chylomicrons from interstine.
- Chylomicron absorbs the fats and brings them to the liver.
- The liver repackages them, altered them, lipoproteins get removed, until the end product: HDL
4 types of lipoproteins:
Very low-density lipoproteins (VLDL)
Intermediate density lipoproteins (IDL)
Low density lipoproteins (LDL)
High density lipoproteins (HDL)