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class 3 - coronary circulation

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Coronary Circulation
the blood flowing through the heart is not available for exchange with heart tissue so there is a special supply of blood. The coronary vessels deliver 5% of blood to heart even though the heart is .5% of mass.
needs that much because of very high demand for glucose and O2
Coronary Circulatory route
blood in aorta falls back to heart filling the tube base and flows into the coronary artery.
when the aortic valve is closed during diastole, the valve cusps dont cover openings to the cor art and flow isn't blocked
during diastole, the cor art is not compressed by beating heart and flow isn't blocked.
blood flow increases in the coronary arteries during vent relaxation - opposite of all arteries
coronary sinus
90% of blood from heart tissue returns to the right atrium by....
a large transverse vein in the coronary sulcus on the posterior side of the heart which collects blood from several coronary veins
angina pectoris
"to strangle the chest"
partial obstruction or reversible ischemia of coronary blood flow can cause chest pain. extended obstruction causes heart cell death
reversible ischemia
temporary lack of blood flow to cardiac muscle
myocardial infarction
heart attack
long term obstruction of coronary circulation causes death of cardiac cells in affected areas
caused by fatty deposits or blood clots
portal system
a circulatory route
blood flows through two consecutive capillary networks before returning to heart
hypothalamus --> anterior pituitary
kidneys
intestines --> liver
anastomoses
point where two blood vessels merge
shuts, venous and arterial
arteriovenous anastomosis
artery flows directly to vein in order to bypass surfaces and decrease heat loss in cold temps
found in extremities like fingers, toes, palms ears
venous anastomosis
most common circulatory route
one vein empties into another
it is an alternate drainage of organs and therefore it is less serious when veins are blocked
arterial anastomosis
two arteries merge as an alternate blood supply route
found in coronary arc and around joints when movement may block pathways
capillary exchange
two way movement of fluid occurs across capillary walls between blood (5% of blood) and surrounding tissues
chemicals pass through endothelial plasma membrane, intercellular clefts, fenestrations or filtration pores
chemicals: K, Na, O2, glucose, amino acids, lipids, antibodies, hormones, organic compounds
Diffusion (capillary exchange)
most important exchange mechanism
lipid soluble substances - steroids, O2, CO2
lipid insoluble substances must pass through channels, pores, or intercellular clefts - glucose & electrolytes
large particles are held back (except in sinusoid)
fluid filters out of the arterial end of the capillary and reenters at the venous end --> bulk movement of protein free water
hydrostatic pressure changes fluid movement direction