8)CHD Flashcards
State four mechanisms by which endothelial cell damage can be caused.
Shear forces, hyperglycaemia, toxins & high cholesterol
Describe the main features of a blood vessel including the types of tissues and cells present.
Intima layer: endothelial cells and a thin layer of connective tissue
Tunica media: Smooth muscle tissue
Tunica externa: Connective tissue and fibroblasts
Name two types of cell involved in the pathogenesis of atherosclerosis and explain briefly how they contribute to the disease process.
Endothelial cells: become damaged then permeable; LDL can now squeeze through gaps and move to the intima layer.
Smooth muscle cells: Migrate in response to growth factors from macrophages and create the fibrous element to plague.
Explain the role of low-density lipoprotein in the pathogenesis of atherosclerosis.
LDL in high levels can damage the endothelial cells or endothelial damage can be caused by other factors. LDL will move through gaps between endothelial cells into the intima layer. Where it will become oxidized by reactive oxygen species released by damaged endothelial cells, engulfed by macrophages to form fatty streak.
State the typical contents of an atherosclerotic plaque.
Macrophages that have become foam cells containing oxidized cholesterol, smooth muscle cells that have migrated from the tunica media, necrotic core and other immune cells, fibrous cap.
State and explain two differences between stable angina and myocardial infarction.
Blood clot: In stable angina no blood clot- MI blood clot- stable angina stable plague MI ruptured plague
Predictability: Angina can be predicted because of demand led ischemia - MI unpredictable ischemia not demand let (canoccur at any time)
Pain: Angina pain fades in 10-15 mins (reversible and demand led) - MI serve pain that does not fade (irreversible ischemia- medical emergency)
State and explain two differences between unstable angina and myocardial infarction.
Blood clot: UA has smaller blood clot that only partially blocks artery- MI bigger stable clot that completely blocks artery.
Reversible/Irreversible: UA clot may start to break down-MI irreversible and causes irreversible ischemia (takes drugs and or stent to remove)
Pain: UA lasts around 30 mins- MI- severe pain that does not fade due to irreversible ischemia.
Describe the mechanism and usual pattern of pain symptoms of stable angina
Mechanism: Stable plague that partially occludes artery. Imbalance of oxygen supply and demand.
Sensation: Tightness, heaviness, aching.
Duration: Last around 10-15mins with rest. nitro glycerine spray can help
Describe the mechanism and usual pattern of pain symptoms in myocardial infarction
Mechanism: Ruptured plague, blood clot that will occlude blood flow causing lack of oxygen and nutrient supply (ischemia).
Sensation: Tightness, heaviness and aching
Duration: serve pain that does not fade can last hours- nitro glycerine spray may not work.
Explain the term Acute Coronary Syndrome
ACS is a range of coronary conditions that include unstable angina and myocardial infraction that are due to atherosclerotic blood clot and sudden reduction of blood reduction of blood flow to the heart.
Describe the mechanism of blood clot (thrombus formation) which occurs in more advanced forms of atherosclerosis such as unstable angina and MI.
Ruptured plague contains collagen & Von Williebrand factor. These attract platelets to aggregate at the site of the rupture. Core activates the conversion of prothrombin to fibrin. Fibrin creates fibres that give more support/ structure to the clot.
