Pathophys - CVS Flashcards
Blood pressure formula
Cardiac output X systemic vascular resistance
What is the significance of the Poiseuille-Hagen formula?
“r” is to the fourth power, so a small change in diameter results in a large change in resistance.
Where is the highest % of blood contained?
Venule
What are the 3 tunica layers of an artery wall?
Tunica externa - tunica media - tunica intima
Where is the smooth muscle found in an artery wall?
In the tunica media
Where is the tunica intima found in an artery wall?
Between the endothelium and internal elastic membrane.
What is found between the internal and external elastic membranes in an artery wall?
Tunica media and the smooth muscle.
What do JNC-8 recommendations for BP look at?
High importance on age: > 60 < 60 > 18 with CKD > 18 with diabetes
What are the six summaries of JNC-8?
- Target goal <140/90
- Relaxation of BP “in the elderly” (>60 yrs)
- No pre-HTN group
- Beta – blockers degraded as fourth line
- Diuretic retained as first line
- Special consideration given to African-Americans, CKD, and DM
Define atherosclerosis
Slow progressive disease of the large elastic and large and medium sized muscular arteries
AKA: arteriosclerosis
Atherosclerosis is characterized by…
the formation of atherosclerotic plaques/atheroma
Atherosclerosis in the general population
- 50% of all deaths in the U.S. are related to cardiovascular disease
- Atheroma can be observed in almost every individual > 40 years of age
Atherosclerosis involves…
the deposition of fatty (cholesterol) plaque (atheroma)
Where are atheromas found?
in the intimal layer of affected arteries –> these will grow and push into the lumen
*Leads to restricted or even blocked blood flow
What do atherosclerosis symptoms rely on?
- the degree of blockage (size)
2. the distribution of the artery (location, location, location)
Atherosclerosis rupture
can lead to thrombus formation and further blockage/symptoms
Atherosclerosis risk factors
- Hyperlipidemia – and specifically hypercholesterolemia
- HTN
- Cigarette smoking
- Diabetes mellitus type I/II
Minor risk factors
- Physical inactivity
- Stress and behavior patterns
- Obesity
- Long term oral contraceptive use
- Tooth decay
Non-alterable risk factors
- Age (older worse than younger)
- Gender (male > female)
- Genetic predisposition (folks had it – you’ll have it)
Cholesterol’s role in metabolic functions
- component with other lipids in the synthesis of cellular membranes
- used to create steroid-based hormones
- excreted as an important element of bile acids
- 93% of the body cholesterol is intracellular
- 7% is circulating as plasma cholesterol bound to a lipoprotein
Good vs. bad cholesterol
- Elevated levels of HDL have a protective effect
- Elevated levels of blood plasma LDL are directly related to the development of clinically significant atherosclerosis
What are the 4 soluble lipoproteins?
- Chylomicrons
- Pre-beta lipoproteins (“very low density lipoprotein”, VLDL)
- Beta lipoproteins (“low density lipoprotein”, LDL)
- Alpha lipoproteins (“high density lipoproteins”, HDL)
Chylomicrons
primarily transport dietary triglycerides and, to a lesser extent, dietary cholesterol
Pre-beta lipoproteins (VLDL)
primarily transport endogenously produced hepatic triglycerides to adipose and muscle tissue
Beta lipoproteins (LDL)
primarily transport endogenous cholesterol and are the major plasma cholesterol carriers
Alpha lipoproteins (HDL)
primarily transport endogenous cholesterol acquired from extra-hepatic tissues and returns it to the liver.
Atheroma development
- Endothelial injury that leads to endothelial dysfunction (leads to increased permeability and increased adhesion of cells to the endothelium)
- Monocyte adhesion followed by migration into the intima
- Platelet adhesion – Von Willebrand factor
- Inflammatory mediators are released by activated platelets, macrophages and endothelial cells
- Accumulation of lipoprotein – mostly LDL cholesterol, at first inside SM and macrophages then in the matrix
Atheroma development cont.
- Smooth muscle cell proliferation and creation of more extracellular matrix
- Lipid accumulation within monocytes and smooth muscle cells to create foam cells
- Infiltration of the extracellular matrix with more lipid leads to FATTY STREAK