CARDIAC OUTPUT
Definition : The ventricles of the heart pump out blood at every beat The quantity of bleed pumped out is called Cardiac output About 70cc of blood is pumped out per beat this is called stroke volume and heart beats at the rate of 70 beats per minute thus in a minute 70*72=5040 ccor approximately 5 litres of blood is being pumped out by the heart this is called the minute output of the heart
Factors Controlling the cardiac output: Cardiac output depends on the cardiac efficiency and the quantity of blood that reaches the heart factors affecting this are :(1) venous return i.e.the quantity of bloud that reaches the heart via superior venacava and inferior venacava:(2) Force (inotropic action) of the heart (3) Frequency (chronotropic action) of the heart beat and (4) Peripheral resistance offered by the peripheral circulatory system
The cardiac output also varies with age sex surface area exercise posture and many other factors as shown in cardiac output is increased during pregnancy anxiety anger and other emotional conditions cardiac output is also increased in hyperthyroidism anaemia fever beri beri angina pectoris etc
Cardiac output is reduced in paroxymal tachycardia auricular fibrillation complete A-V block valvular diseases myxoedema pneumothorax haemorrhage surgical shock arterial hypertension and post -operative conditions
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| Factors responsible for increased output |
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