University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2019
Views:

279

Pages:

6
Author:

harvestglobalki

Cardiac Output (CO) • Amount ejected by each ventricle in 1 minute • CO = Heart Rate (beats/min) x Stroke Volume (ml/beat) • Resting values, CO = 75 beats/min x70 ml/beat = 5,250 ml/min, usually about 4 to 6 liters/min • Vigorous exercise  CO to 21 L/min for fit person and up to 35 L/min for world class athlete • Cardiac reserve: difference between a person’s maximum CO and resting CO –  with fitness,  with disease • Right Ventricle and Left Ventricle eject the same amount of blood. Preload • Preload is the amount of tension in ventricular myocardium before it contracts. •  preload causes  contraction strength – exercise  venous return, stretches myocardium ( preload) , myocytes generate more tension during contraction,  CO matches  venous return • Frank-Starling law of heart: StrokeVolume  End Diastolic Volume – ventricles eject as much blood as they receive; The more they are stretched ( preload) the harder they contract. Unbalanced Ventricular Output Unbalanced Ventricular Output Heart Rate • • • • • • Heart Rate (HR) can be measured from pulse. Infants have HR of 120 beats per minute or more Young adult females average 72 - 80 bpm Young adult males average 64 to 72 bpm HR rises again in the elderly Indurance trained athletes have resting heart rates around 40 bpm – Miguel Indurain, 5 time Tour de France winner (1991-1995), had a resting heart rate of 28 bpm and a cardiac output of 50 liters/minute Heart Rate • Tachycardia: persistent, resting adult HR > 100 – can be caused by stress, anxiety, drugs, heart disease or  body temperature • Bradycardia: persistent, resting adult HR < 60 – common during sleep and also in endurance trained athletes