Chronotropic Effects of Chemicals

Chronotropic Effects of Chemicals - Cardiovascular System...

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Cardiovascular System Chronotropic Effects of Chemicals * Hyperkalemia (excess K+) * rapid rise makes the myocardium unusually excitable and subject to systolic arrest (ventricles contract and fail to rest) * slow rise makes it less excitable than normal; the heart rate becomes slow and irregular and may arrest in diastole * Hypokalemia (K+ defficiency)- myocytes become hyperpolarized which makes it more difficult to stimulate the cells to threshold * Hypercalcemia - reduces the heart rate and strengthens contraction strength * Hypocalcemia - increases the heart rate and weakens contraction Circulatory Routes * Usual route of blood is * heart * arteries * arterioles * capillaries * venules * veins * heart Circulatory Routes * Portal system- blood flows through two consecutive capillary beds before returning to the heart Circulatory Routes * Anastomosis - a point where two blood vessels merge * Arteriovenous anastomosis (shunt)- when blood flows from an artery directly into a vein and bypasses the capillaries
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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Chronotropic Effects of Chemicals - Cardiovascular System...

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