This site is 100% ad supported. Please add an exception to adblock for this site.

Physiological Science 111B Module 2 Lecture 8

Terms

undefined, object
copy deck
What structures provide blood to the heart and where do they originate?
Coronary arteries stem off the aorta: right coronary, right ventricle, left main, left anterior descending, circumflex.
Which coronary arteries receive the most blood flow and why?
The left anterior descending and the circumflex coronary arteries receive the most blood flow because of the thicker wall and increased work performed by the left ventricle.
Heart vs. Skeletal Muscle O2 Demands
Heart: aerobic muscle requiring constant O2 supply
Heart: extracts 60-70% of the O2
Skeletal Muscle: extracts 20-40% of the O2
Since heart extracts a high percentage of O2 at rest, increases in O2 demand must be met by an increase in coronary blood flow.
What can happen when the O2 demand exceeds the O2 supply?
1) The heart becomes ISCHEMIC (lack of O2) due to an O2 supply/demand imbalance.
2) A MYOCARDIAL INFARCTION (MI), or heart attack, is a condition of irreversible necrosis of cardiac muscle that is the result of prolonged periods of ischemia.
(Prolonged ischemia->MI/Heart Attack->irreversible necrosis)
ATHEROSCLEROSIS
1) Definition/Where Occurs
2) What do atherosclerotic plaques consist of?
3) The most common type of ischemia is in the ___ due to ___ where the condition is termed ___.
4) The second most common site is the ___ in th
1) an accumulation of lipids and fibrous elements in large arteries, usually at bifurcations where blood flow is turbulent, reducing the amount of blood flow and O2 the heart and brain receive.
2) cholesterol, inflammatory cells, fibrosis
3) heart; blockage of coronary arteries; coronary artery disease (CAD)
4) carotid arteries; neck; stroke; “brain attack”
5) leg arteries; peripheral vascular disease; claudication
6) 39%, ~75%; 7) high blood cholesterol
STAGES OF ATHEROSCLEROSIS: FATTY STREAKS
Definition, Fetus, Physiological Consequences
___ of teenagers in US have ___ if they have grown up on a typical US diet
-Oxidized cholesterol and lipid accumulate under the endothelium in WBCs called “foam cells”
-Some aborted fetuses have fatty streaks due to high cholesterol in mother
-Often seen in males by teens and females by teens through 50s
-No impedance of flow at this point-> no physiological consequences
-70%
STAGES OF ATHEROSCLEROSIS: INTERMEDIATE LESION (FIBROUS PLAQUE)
Definition; what provides a protective effect and for whom?; age distribution
-excessive accumulation of lipid-rich necrotic debris and SMCs form a fibrous lesion; a fibrous cap consisting of SMCs that forms that encloses the necrotic core
-estrogen provides a protective effect, so fibrous plaque in women usually does not appear until after menopause
-seen often in males by 20s and females by 50s-60s
STAGES OF ATHEROSCLEROSIS: ADVANCED LESION
Definition; age distribution
-calcification cause a hardening of the lesion and continued progression of lesion development
-seen often by 30s-40s in males and 70s in females
STAGES OF ATHEROSCLEROSIS: CLINICAL EVENT: HEART ATTACK/STROKE
Definition, age distribution, % blockage
-vulnerable plaques rupture, and resulting blood clot stops blood flow & O2 to the heart/brain
-seen by 50s-60s in males and 70s-80s in females
-need <50% (2/3 of cases) to occur, but 80-90% blockage less likely to cause heart attack b/c plaque is stable and unlikely to rupture; these are non-hemodynamically significant and asymptomatic; they have a tendency to rupture/erode and so are called “vulnerable plaques”
When can one detect coronary artery disease?
The complicated plaque stage; some people get angina pectoris but less than half do so. In more than ½ of deaths by heart attack, the heart attack is the first warning of disease.
SURGICAL METHODS FOR CORONARY ARTERY DISEASE (CAD)
1) Coronary Artery Bypass Graft (CABG): blocked arteries bypassed using graft (usu saphenous vein). If all 4 major coronary arteries blocked = quadruple bypass. It is debatable whether it protects against MI or produces signif. life prolongation.
2) Angioplasty: catheter inserted with balloon on the end, expands & crushes plaque to establish reperfusion & prevent irreversible damage. However associated w/ high incidence of reocclusion b/c of a predilection to clot formation and SMC proliferation in endothelium damage site.
Most important factors governing cholesterol accumulation in the artery wall:
1) amount of cholesterol in the blood
2) susceptibility of cholesterol oxidation
What is the most important factor that affects blood cholesterol level?
DIET
1) Saturated fat/trans fat intake
2) cholesterol intake
3) fiber intake
Total Cholesterol (mg/dl) and LDL (mg/dl) levels: Desirable/Borderline/High Risk
Total Cholesterol: <200, 200-239, >240
LDL: <130, 130-159, >160
Major Risk Factors for Coronary Artery Disease
1) Elevated serum cholesterol; 2) smoking
3) Hypertension (high BP); 4) Diabetes (glucose intolerance)
5) Insulin resistance/hyperinsulinemia (poor insulin fxn/high blood insulin levels)
6) Hypertryglyceridemia (high levels of fat in the blood)
7) Physical Inactivity (low fitness)
As more risk factors are present (and with greater BCL), risk of atherosclerosis rises exponentially. All factors damage artery walls and thus allow cholesterol to enter at a rapid rate.
Factors Protecting Against Atherosclerosis:
1) low-fat, low refined-carbohydrate, low cholesterol, high-fiber diet
2) high fitness
3) low stress
4) estrogen
5) high high-density lipoprotein (HDL) cholesterol

Deck Info

16

permalink