VASCULAR LECTURE 1: Htn & atherosclerosis Flashcards
What values are considered hypertension?
> 135 / >85
What is BP >180 / >120 considered as?
Hypertensive crisis
What is blood pressure the product of?
Cardiac output x peripheral resistance
What are 3 things cardiac output is determined by?
Blood volume, heart rate, contractility
What 2 things determine blood volume?
Sodium, kidney function
What are 2 categories of factors that determine blood vessel diameter?
Humoural factors (endocrine)
Neural factors
Name some examples of endocrine factors that cause contriction in peripheral vessels
Angiotensin II
Catecholamines
Thromboxane
Leukotrienes
Endothelin
Name some examples of endocrine factors that cause dilation in peripheral vessels
Prostaglandins
Kinins
NO
What neural factors cause constriction in peripheral vasculature?
Alpha adrenergic
What neural factors cause dilation in peripheral vasculature?
Beta adrenergic
Which kind of hypertension is the most common, and is due to an idiopathic cause, like non-specific lifestyle/genetic factors?
Primary/essential hypertension
Which kind of hypertension is more rare (5-10%) and is due to an identifiable cause, eg water/salt imbalance?
Secondary hypertension
What are two main problems that cause arterial flow disorders?
- Narrowed/blocked arterial lumen
- Weakening of arterial walls leading to aneurysm/rupture
What is the name of the layer where atherosclerotic plaques develop?
Intima
What are the 3 layers of a plaque?
- Fibrous cap
- Necrotic center
- Media
What are 3 main components of the fibrous cap?
- Cells (smooth muscle, macrophages, immune cells)
- ECM (collagen, elastic fibers, proteoglycans)
- Lipids (intra and extracellular)
What are 2 complicaitons that can happen to plaques?
- Vaso vasorum may hemorrage inside plaque
- Calcification
What is the earliest sign of atherosclerosis?
Fatty streak on arterial walls
Why is diabetes a risk factor for atherosclerosis?
Vascular inflammation caused by hyperglycemia
Why is smoking a risk factor for atherosclerosis?
Chemicals are vasoconstrictors, cause endothelial damage
Why must lipids be converted to lipoproteins for metabolism?
Lipids are hydrophobic, so must be combined with proteins to become water soluble and interact with cell membrane receptors
What is the difference between the exogenous and endogenous pathways of lipids entering the blood?
Exogenous: From diet
Endogenous: Synthesized by liver
In the exogenous pathway of lipids entering the bloodstream, fatty acids are absorbed by the small intestine and packaged into what?
Chylomicrons
After chylomicrons are formed, how are they transported into the blood?
Via lymphatic system
In the endogenous pathyway of lipids entering the bloodstream, the liver assembles triglycerides and fatty acids into what?
VLDLs (very low density lipoproteins)
How do VLDLs become LDLs?
Triglycerides are removed by various cells
In what form does the majority of blood cholesterol move through the body?
LDLs (low density lipoproteins)
What is the danger of high levels of LDLs in the blood?
They can be taken up by “unauthorized” tissues
What are 2 pieces of evidence correlating hypercholesterolemia with atherosclerosis?
- The majority of lipids in plaques are mainly cholesterol
- Reducing LDL levels has been shown to slow atherosclerosis or even cause regression
What is the trigger in pathogenesis of an atherosclerotic plaque?
Damage to endothelium which leads to increased permeability and cell adhesion (inflammation)
How is the initial lesion formed in atherosclerosis? (2 points)
- Endothelial cells release inflammatory mediators to recruit T cells and smooth muscle cells
- Macrophages and lipids infiltrate into the intima
How is the fatty streak formed in atherosclerosis? (2 points)
- Macrophages take up lipids and become foam cells
- LDLs accumulate and oxidize
How is the intermediate lesion formed in atherosclerosis? (2 points)
- Smooth muscle cells proliferate and produce extracellular matrix, thickening the vessel wall
- Cells die, causing lipid debris to accumulate
How is an atheroma formed in atherosclerosis?
The plaque’s core of extracellular lipid becomes necrotic
What are 2 things that characterize an atherosclerotic plaque as a fibroatheroma?
- Single or multiple lipid cores
- Fibrotic/calcified layers
What are 3 things that characterize an atherosclerotic plaque as a complicated lesion?
- Surface defect
- Erosion of vasa vasorum causes hemorrhage into the plaque
- Thrombosis
