PTHY208 blood flow disorders week 4.1.1 athrosclerosis

PTHY208 blood flow disorders week 4.1

what is Lipoprotein

A complex that transports insoluble lipids in blood (cholesterol, triglycerides, phospholipids + protein)

Triglycerides function

Energy metabolism

Cholesterol function

produce Cell membranes, steroid hormones, bile acids

HDL function

Removes cholesterol from arterial walls to liver ("good cholesterol")

LDL function

Deposits cholesterol in arterial walls and accumulates in subendothelial space

VLDL function

Transports triglycerides to tissues for energy

Chylomicrons function

Transport triglycerides and cholesterol from intestine to liver,

why is Abnormal lipoprotein metabolism important

Predisposes to atherosclerosis

what are Non-modifiable risk factors (atherosclerosis)

Familial hypercholesterolaemia;

age (men ≥45, women ≥55);

type 1 diabetes

what are Modifiable risk factors (atherosclerosis)

Low HDL (<40 mg/dL);

high CRP;

high homocysteine

where does atherosclerosis occur

Intimal lining of arteries (coronary, cerebral, peripheral, aorta)

Stages/lesions of atherosclerosis

Fatty streaks; fibrous atheromatous plaque; complicated lesion

Onset of atherosclerosis (when begins)

Can begin in childhood (fatty streaks)

First step in atherosclerosis

Endothelial dysfunction (decrease in NO (vasodilation) microtears)

Cause of endothelial dysfunction

Loss of nitric oxide, microtears, risk factors

what happens during endothelial dysfunction

Increased permeability, leukocyte adhesion (becoms sticky), inflammation (due to WBC)

what Triggers inflammation in in vessel wall (athroscllerosis)

Entry and oxidation of LDL

Role of monocytes/macrophages

Enter vessel wall, become macrophages, ingest ox-LDL

what are Foam cells

Lipid-filled macrophages forming fatty streaks

Role of smooth muscle cells (SMCs)

Migrate, proliferate, contribute to plaque

what happens when ox-LDL excessive

Cytotoxic → cell death → necrotic core formation

what is Necrotic core

Dead cells and cholesterol crystals in plaque

Fibrous cap composition

Connective tissue, fibrin, calcium

characterisitcs of a Stable plaque

Small lipid core, thick fibrous cap, low rupture risk

characteristics of a vulnerable plaque Vulnerable plaque

Large lipid core, thin fibrous cap, high inflammation, high rupture risk

what two ways plaues cause disease

Chronic narrowing OR acute rupture with thrombosis

what happens during Plaque rupture

Cap breaks → platelet aggregation → thrombus (clot) → reduced/blocked blood flow

Causes of arterial obstruction

Thrombosis; atherosclerosis; embolism; trauma; iatrogenic

what is Acute arterial occlusion

Sudden arterial blockage causing rapid ischaemia

Clinical features of arterial obstruction?

Ischaemia, tissue necrosis (depends on site/severity)

what are the Six Ps of acute limb ischaemia

Pain; pallor; pulselessness; paresthesia; paralysis; poikilothermia