cardiovascular week 3 Flashcards
Describe the body’s response to exercise
when local tissue blood vessels dilate, venous return increases and cardiac output raises above normal to prevent the blood pressure to fall dramatically
What is atherosclerosis?
A disease characterised by the formation of focal elevated lesions in the intima of large and medium sized arteries.
When does atherosclerotic plaques become life threatening/
when an occlusive thrombus forms on a spontaneously disrupted plaque
Describe the beginning of the formation of lesions
starts in young children
earliest significant lesion is called a fatty streak
yellow linear elevation of the intimated lining and is composed of masses of lipid-laden macrophages.
no clinical significance
Describe a fully developed plaque
central lipid core
cap of fibrous tissue covered by arterial endothelium
connective tissues in cap such as collagens provide structural integrity and are produced from smooth muscle cells
Inflam cells such as macrophages, T lymphocytes and mast cells also reside in the cap
these are recruited from arterial endothelium or in advanced plaques from newly formed micro-vessels
Describe atheromatous lesions
rich in cellular lipids and debris
they are soft, semi-fluid, highly thrombogenic lesions often bordered by a rim of “foam cells”
What are foam cells?
macrophages which have phaogcytosed oxidised lipoproteins via a specialised membrane-bound scavenger receptor
they have large amounts of cytoplasm with a foamy appearance
What can happen to plaques in the late stages?
calcification
Where do plaques have a tendency to form and why?
arterial branching points and bifurcations
the important role of turbulent blood flow in the pathogenesis of atherosclerosis
What are risk factors for atherosclerosis?
hypercholesterolaemia is by far the most important smoking hypertension male gender increasing age less strong risk factors; obesity sedentary lifestyle low socio-economic status low birth weight
What is the process by which lesions usually develop?
injury to the endothelium of the arterial wall
tissue response of the vascular wall to injurious agents
chronic or episodic exposure to of the arterial wall to these processes leads over many years to the formation of plaques
What are the typical symptoms of angina?
constricting discomfort in the front of chest, arms, neck and jaw
provoked by physical exertion, especially after meals and in cold, windy weather or by anger or excitement
relieved (usually in minutes) by rest or glycerol trinitrate
What is stable angina?
when it is not a new symptom and when there is no change in the frequency or severity of attacks
What is unstable angina?
recent onset or a deterioration in previously stable angina with symptoms frequently occurring at rest
What are some of the clinical manifestations of atherosclerosis?
progressive lumen narrowing leading to high-grade plaque stenosis
acute atherothrombonic occlusion
embolisation to distal arterial bed
ruptured abdominal atherosclerotic aneurysm
Describe thombosis
a mass of constituents formed within the vascular system in life
predisposing factors (Virchow’s triad) abnormalities in blood vessel wall, abnormalities in blood flow, abnormalities in blood constituents
arterial thrombosis is most commonly superimposed on atheroma
venous thrombosis normally occurs due to stasis
Describe the clinical effects of thrombosis
loss of pulse distal to the thrombus and all the signs of impaired blood flow are present
myocardial infection due to thrombus formation in the coronary arteries
strokes due to thrombosis in a cerebral vessel
What does the PR interval represent?
the time taken for activation to pass from the sinus node, through the atrium, AV node and His-purkinke system to the ventricles
What does the QT interval represent?
the time taken to depolarise and depolarise the ventricular myocardium
What does the ST segment represent?
Ventricular repolarisation
What may be seen on an ECG for an angina patient?
transient ST depression
What are some treatment options for coronary artery disease?
anti-angina drugs anti-platelet drugs (aspirin) thrombolytic drugs angioplasty and stents CABG surgery secondary prevention
Describe nitravasodilators
reduce venous return glycerol trinitrate used most commonly taken sub-lingually isorbide denitrate (long lasting) lipophilic -readily enter muscle cells and are reduced to nitric oxide NO donors mimic action of endothelium derived NO
What is cholesterol essential for?
incorporating into cell membrane
maintaining membrane fluidity and permeability
production of steroids and fat-soluble vitamins
Describe the relationship between the liver and cholesterol
monitors levels of cholesterol
regulates this through synthesis, absorption, bile secretion
drugs to treat hyperlipidaemia target the liver
Describe cholesterol and lipoproteins
macromolecular complexes of; lipids cholesteryl ester triglycerides free cholesterol phospholipids
Give examples of lipoproteins
chylomicrons VLDL IDL LDL HDL
Describe chylomicrons
carry TGs from intestines to liver, muscle and adipose tissue
Describe VLDL
carry newly synthesised TGs from liver to adipose tissue
Describe IDL
an intermediate between VLDL and LDL
Describe LDL
major reserve of cholesterol
taken up by LDL receptors by endocytosis
Describe HDL
absorb cholesterol released by dying cells
also act as “reserve transport” to take cholesterol to live
Describe HMGCoAR inhibitors
“statins”
competitive inhibitors of the rate-determining step in cholesterol biosynthesis
marked decrease in cholesterol levels may stimulate LDL receptor up-regulation
usually taken at night
What causes Von Willebrands disease?
Deficiency in VW factor
What is haemophilia A?
deficiency of factor VIII
What is haemophilia B?
Deficiency in factor IX
What is haemophilia C?
Deficiency in factor XI
