Heart disease

Heart disease

Atheroma
1. Fatty deposit that forms within the walls of an artery
2. Begins as fatty streaks - accumulations of white blood cells that have taken up low-density lipoproteins
  1. Compound containing proteins and lipids
  2. Found in blood plasma and lymph
  3. Carry cholesterol from the liver
3. These sttreaks enlarge to form an irregular patch
  1. Atheromatous plaque
4. Atheromatous plaques most commonly occur in larger arteries
  1. Made up of cholersterol, fibres and dead muscle cells
5. Bulge into the lumen of the artery, narrowing it so blood flow is restricted
6. Increases the risk of two potentially dangerous conditions - thrombosis and aneurysm
Thrombosis
1. If an atheroma breaks through the lining (endothelium) of the blood vessel, it forms a rough surface that interrupts the otherwise smooth flow of blood
2. This could result in a blood clot, or thrombus, in a condition known as thrombosis
3. The thrombus may block the blood vessel, reducing or preventing the supply of blood to the tissues beyond it
4. The region of tissue deprived of blood often dies from lack of oxygen, glucose and other nutrients the blood normally provides
5. Sometimes a thrombus is carried from its place of origin and lodges itself in another artery, and blocking it instead
Aneurysm
1. Atheromas that lead to the formation of a thrombus also weaken the artery walls
2. The weakened points and swell to form a balloon like, blood filled structure called an aneurysm
3. These often burst, leading to a haemorrhage and therefore loss of blood to the region of the body served by that artery
4. A brain aneurysm is knkown as a cerebrovascular accident (CVA) or a stroke
Myocardial infarction
1. Most commonly known as a heart attack
2. Refers to a reduced supply of oxygen to the muscle of the heart - the myocardium
3. It results from a blockage in the coronary arteries
4. If it occurs close to the junction of the coronary artery and the aorta, the heart will stop beating as its blood supply is completely cut off
5. If the blockage is futher along the coronary arter, the symptoms will be milder because a smaller area of muscle will suffer oxygen deprivation
Risk factors
1. Smoking
  1. Carbon monoxide
    1. Combines easily but irreversably to haemoglobin on red blood cells that should carry oxygen
    2. Reducing the oxygen-carrying capacity
    3. To supply the same amount of oxygen, the heart must work faster
    4. Leads to increased bp, increasing risk of CHD and strokes
    5. Can lead to reduction of oxygen to heart during exercise, causing angina or myocardial infarction
  2. Nicotine
    1. Stimulates production of the hormone adrenaline, which increases heart rate and bp
    2. Greater risk of CHD or stroke
    3. Makes platelets more sticky, leading to higher risk of thrombosis and hence of strokes and myocardial infarction
2. High bp
  1. Increased pressure in the arteries means the heart must work harder to pump blood into them and therefore is more prone to failure
  2. Higher bp within the arteries means they are more likely to have an aneurysm and burst
  3. To resist the pressure, the walls of the arteries tend to thicken and harden, restricting blood flow
3. Cholesterol
  1. Essential component of membranes
  2. Essential biochemical which must be transported
  3. Carried in the plasma
  4. Two types of lypoproteins that carry cholesterol
    1. High density
      1. Remove cholesterol from tissues and transport it
    2. Low density
      1. Transport cholesterol from liver to tissues including artery walls
  5. They infiltrate artery walls leading to the developent of atheroma
4. Diet
  1. High salt levels
    1. Increase blood pressure
  2. High levels of saturated fat
    1. Increase low density lipoprotein levels and hence blood cholesterol concentration
  3. Foods that act as antioxidants reduce risk of heart disease, and so does dietary fibre

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	Created by Beth Ritchie over 10 years ago