Lecture 9 Flashcards
Define atheroma
The accumulation of intracellular and extracellular lipid in the intima of large and medium sized arteries
How long does atherosclerosis take to develop?
Several years
When can atherosclerosis start?
As early as infancy and childhood and progresses very slowly during life
The accumulation of what results in the formation of atherosclerosis? (4)
- lipid
- connective tissue
- inflammatory cells
- smooth muscle cells
What does the Greek work atheros mean?
Gruel or paste
What does the Greek work sclerosis mean?
Hardness
Where can atheromas form? (5)
- Intimal lining of large and medium sized arteries such as the aorta and its branches
- The coronary arteries
- The large vessels that supply the brain
- Carotid arteries
- Leg arteries
How is atherosclerosis detected?
- Typically asymptomatic
- Usually found after a heart attack or stroke
- ## Measure of LDL in blood as a predictor
What are the three layers of the artery?
- Intima
- Media
- Adventitia
What layer of the artery contributes most to its mechanical strength?
The medial layer
What are the macroscopic features of an atheroma?
- Fatty streak
- Simple fibrous plaque
- Complicated plaque
What is a fatty streak?
Compromises a slightly elevated zone on the arterial wall caused by accumulation of a small number of lipid laden cells
What is a simple fibrous plaque?
- Lipid accumulated both free and in cells
- Smooth muscle cells also migrate from the media
- Fibrosis develops around the lipid and forms a cap over the lesion
What is a compliacated plaque?
Ulcers and fissures of the fibrous cap expose plaque contents resulting in thrombosis
What is the development of atherosclerosis initiated by?
Endothelial dysfunction
What are the main components of plaque? (3)
- Lipid containing macrophages
- Extracellular matrix
- Proliferating smooth muscle cells
Where is cholesterol absorbed?
Intestine
Where is cholesterol produced?
Liver
What is the daily cholesterol dietary intake?
300mg
How much cholesterol is synthesized per day?
1 gram
How is cholesterol carried in the blood?
Attached to proteins called lipoproteins
What are the two forms of lipoproteins?
- Low density lipoproteins
- High density lipoproteins
How is LDL removed from the circulation
- By LDL receptor or
- By scavenger cells such as monocytes or macrophages
How is 70% of LDL removed?
By receptor dependent pathway