PHTY208 Lecture Notes - Lecture 8: Edema, Subcutaneous Tissue, Femoral Vein
Disorders of blood flow in the systemic circulation
• Disorders of blood flow can cause hypoxia and impaired oxygenation of local tissue
• Disturbances can result from changes in
o Vessel walls - atherosclerosis, vasculitis
o Acute vessel obstruction
o Abnormal vessel dilation - aneurysms or varicose veins
• Disorders of arterial circulation
o Hyperlipidemia
• High amount of lipids
• Can be an elevation of one or more than these:
▪ Triglycerides
• Used in energy metabolism
▪ Phospholipids
• Important structural constituents of lipoproteins, bloodclotting
components, the myelin sheath, and cell membranes
▪ Cholesterol
• Chemical activity similar to other lipid substances
• Type of lipoproteins
▪ Chylomicrons
▪ Very–low-density lipoprotein (VLDL)
• Carries large amounts of triglycerides
▪ Intermediate-density lipoprotein (IDL)
▪ Low-density lipoprotein (LDL)
• Main carrier of cholesterol
• Bad fats
▪ High-density lipoprotein (HDL)
• 50% protein
• Good fats
• Hypercholesterolemia
▪ Elevated serum cholesterol levels
•
240 mg/dL or greater
•
Levels that could contribute to a heart attack, stroke, or other
cardiovascular event associated with atherosclerosis
▪ Primary hypercholesterolemia
•
Elevated cholesterol levels that develop independent of other
health problems or lifestyle behaviors
▪ Secondary hypercholesterolemia
•
Elevated cholesterol levels that are associated with other health
problems and behaviors
▪ Implicated in the development of atherosclerosis
▪ Management
•
Reduction of LDL cholesterol
• Diet (reduce saturated and trans fat)
• Exercise
• Weight reduction if overweight
• Smoking cessation
• Lipid and/or cholesterol lowering drugs
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o Atherosclerosis
• Development
▪ Formation of fibrofatty lesions in the intimal lining that fills and stiffens
the larger and medium-sized arteries
▪ These plaques are often complicated by thrombus
▪ Types of lesions associated with atherosclerosis
• Fatty streaks
• Fibrous atheromatous plaque
• Complicated lesion
▪ A plaque will damage the vessel and change the architecture of the
vessel
• The blood vessel becomes twisted further impeding blood flow
▪ Initial event in plaque development is endothelial dysfunction
• Chemical irritants (smoking), haemodynamic stress
(hypertension)
▪ LDL and VLDL infiltrate vessel wall which can lead to further endothelial
dysfunction and inflammation
▪ Other cells migrate into the area
• Monocytes which become macrophages, T-lymphocytes and
smooth muscle cells
▪ These cells consume the fats for oxidation
• Cytotoxic at high levels
• Results in a hypoxic core
▪ Leads to fibrin infiltration and development of fibrous cap – stiffening
wall
▪ Calcium is deposited also contributing to hardening of vessel wall
• Fate of plaque
▪ Can continue to grow and cause narrowing of the vessel and production
of ischemia (reduction of blood flow)
•
Ischemia can result in hypoxia
▪ “tale plaue
•
Small lipid pool with thick fibrous cap and preserved lumen
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▪ Vuleale plaue
•
Large lipid pool, thin fibrous cap, many inflammatory cells
•
Can commonly rupture and cause a thrombus which can further
lead to narrowing
▪ Sudden vessel obstruction due to plaque haemorrhage or rupture
•
Acute myocardial infarction
▪ Occasionally the rupture can heal
•
Narrowed lumen
•
Fibrous intima
▪ Aneurysm formation due to weakening of the vessel wall
• Specific arterial involvement in atherosclerosis
▪ Larger vessels: the important complications are those of thrombus
formation and weakening of the vessel wall
▪ Medium-sized arteries: ischemia and infarction due to vessel occlusion
are more common
▪ Arteries supplying the heart, brain, kidneys, lower extremities, and
small intestine: most frequently involved
• Risk factors
▪ Hypercholesterolemia
▪ Cigarette smoking
▪ Hypertension
▪ Obesity
▪ Diabetes mellitus
▪ Family history of premature chronic heart disease (CHD) in a first-
degree relative
▪ Age e ≥ yeas; oe ≥ yeas
▪ HDL cholesterol <40 mg/dL
▪ C-reactive protein levels
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Document Summary
Important structural constituents of lipoproteins, bloodclotting components, the myelin sheath, and cell membranes: cholesterol, chemical activity similar to other lipid substances, type of lipoproteins, chylomicrons, very low-density lipoprotein (vldl, carries large amounts of triglycerides. Secondary hypercholesterolemia: elevated cholesterol levels that are associated with other health problems and behaviors. Implicated in the development of atherosclerosis: management, reduction of ldl cholesterol, diet (reduce saturated and trans fat, exercise, weight reduction if overweight, smoking cessation, lipid and/or cholesterol lowering drugs, atherosclerosis, development. Formation of fibrofatty lesions in the intimal lining that fills and stiffens the larger and medium-sized arteries: these plaques are often complicated by thrombus, types of lesions associated with atherosclerosis. Fibrous atheromatous plaque: complicated lesion, a plaque will damage the vessel and change the architecture of the vessel, the blood vessel becomes twisted further impeding blood flow. Initial event in plaque development is endothelial dysfunction: chemical irritants (smoking), haemodynamic stress (hypertension)
