Heart -Supply of blood

Heart receives <5% (4.7%) of cardiac output at rest
• Coronary blood flow is 250mL/min at rest- this can increase by 200-300% (500- 750mL/min)

• In terms of per 100g/ min, coronary blood flow-84mL/100g/min (blood flow in resting skeletal
muscle is 3- 4mL/100g/min; increases to 50 to 80mL/100g/min during exercise)

• Heart is a hard working organ (”thank God”),needs a lot of oxygen!

• Basal oxygen consumption (ref Ganong pg 550 24th edi)- 2mL/100g/min (much more than the
oxygen consumption by resting skeletal muscle,which is 0.2mL/100g/min)

• Oxygen consumption by a beating heart-9mL/100g/min

• At rest heart extracts 70-80% of the oxygenfrom each unit of blood delivered to it (“heart is the organ with maximum oxygen extraction at  rest”). So whenever there is an increase in oxygen demand coronary blood flow will also show an increase.