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Factors that Influence Heart Rate


from adrenal medulla enhances heart rate and contractility


Increases heart rate and enhances the effects of norepinephrine and epinephrine

Factors that Influence Heart Rate

•Body temperature


abnormally fast heart rate (>100 bpm)

If persistent, may lead to fibrillation


heart rate slower than 60 bpm

May result in grossly inadequate blood circulation

May be desirable result of endurance training

Congestive Heart Failure (CHF)

Progressive condition where the CO is so low that blood circulation is inadequate to meet tissue needs

Embryonic heart chambers

Sinus venous
Bulbus cordis

Foramen ovale

connects the two atria in a fetal heart

Ductus arteriosus

connects the pulmonary trunk and the aorta

Congenital heart defects

Lead to mixing of systemic and pulmonary blood

Involve narrowed valves or vessels that increase the workload on the heart

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