Alterations of cardiovascular function Flashcards
Vessel diameter pattern
Large at aorta -> smaller until smallest at capillaries -> larger again until largest at venae caveae
Total cross-sectional area pattern of blood vessels
smallest at aorta and vanae caveae and largest at capillaries
Average blood pressure patterns
Largest at aorta and smallest at venae caveae
Velocity of blood flow patter
- volume makes blood flow faster in veins even though there is low BP
- highest at aorta (starting as a river), lowest at capillaries (like in a field) and high again at venae caveae *going back into a river)
Atherosclerosis
- most common type of arteriosclerosis which is a group of 3 diseases
- “hardening of the arteries”
- arteries become very stiff and thickened due to the deposition of fibro-fatty plaques between layers of the vessel wall
Between what two layers of the vessel wall do the fibro-fatty plaques deposit?
tunica media and tunica intima
Epidemiology of atherosclerosis
- no disease in the U.S is responsible for more deaths
- very prevalent - North America, Europe, Austraila, Russia and developed nations
- mortality rate for ischemic heart disease in USA is 6x higher than that of Japan
Risk factors for atherosclerosis
- Age: risk rises with each decade
- Sex: Males more prone than females
- Familial Predisposition
- Acquired risk factors
Age as a risk factor for atherosclerosis
- early stages of atherosclerotic disease are seen in young children
- from age 40 to age 60 there is a fivefold increase in incidence of myocardial infarct
Sex as a risk factor for atherosclerosis
- between ages 35 and 55, mortality rate for white women is one fifth that of white men
- after menopause, risk increases in women, rates are same for both sexes in their 60’s and 70’s
Familial predisposition as a risk factor for atherosclerosis
- family risk for hypertension or diabetes
- high blood lipid levels due to genetics
Acquired Risk Factors for atherosclerosis
“the big 4”
- high blood lipid levels due to diet
- hypertension
- cigarette smoking
- diabetes mellitus
Acquired Risk Factors: Hyperlipidemia
- high total cholesterol levels increase risk of atherosclerosis
- atherosclerosis is very unusual with total serum cholesterol levels below 150 mg/dl
Different types of cholesterol
LDL and HDL
-lipoproteins are carrier molecules which transport cholesterol in the bloodstream (hypercholesterolemia)
LDL
- low-density lipoproteins: “bad cholesterol”
- believed to mobilize lipid into the bloodstream
HDL
- high-density lipoproteins: “good cholesterol”
- high = healthy
- believed to mobilize lipid from cells and from plaques to the liver for excretion in the bile (taking from blood into tissues)
Significance of types of cholesterol
- a high level of LDL is a strong indicator of risk of coronary and atherosclerotic disease
- increased LDL has been shown to results in endothelial dysfunction (damaged cause clotting)
- HDL’s are though to prevent or relay atherogenesis and to thus be protective
- exercise raises the HDL level
- Obesity and smoking both lower the HDL level.
Acquired Risk Factors: Hypertension
- may be more important than hypercholesterolemia after age 45
- men age 45-62 whose blood pressure exceeds 160/95 mmHg have a fivefold greater risk than men with blood pressures 140/90 mmHg.
Acquired Risk Factors: Smoking
- smoking one or more packs of cigarettes a day for several years increases the death rate from ischemic heart disease by up to 200%
- cessation of smoking reduces this risk with time
Acquired Risk Factors: Diabetes Mellitus
- specifically type II
- diabetes induces hypercholesterolemia
- the incidence of myocardial infarction is twice as high in diabetics
- diabetics also have an increased risk of stroke
- diabetics have a 100-fold increased risk of atherosclerosis-induced gangrene of the lower extremities (poor circulation)
