Examville.com - Physiology - Cardiac Output
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Examville.com - Physiology - Cardiac Output as PDF for free.
More details
- Words: 360
- Pages: 5
Examville is a global education community where users like you can connect and interact with other students and teachers from around the world. Share, seek, download and discuss everything inside and outside the classroom. All you need is an email address and a password to get started.
JOIN US FOR FREE: http://www.examville.com
© Examville.com, LLC June 2009
CARDIAC OUTPUT Cardiac output is defined as the amount of blood pumped out by each ventricle per minute into the circulation. Stroke volume – The amount of blood pumped out by each ventricle per beat. Cardiac output = Heart rate x
Stroke volume
= 5-6 L/min It means cardiac output is controlled by heart rate and stroke volume. Factors affecting heart rate Cardiac innervations Cardiovascular centers----- vasomotor centre and vagal centre
Factors affecting stroke volume Stroke volume is affected by contractibility, after load and pre load
FRANK STARLING LAW Force of ventricular contraction is directly proportional muscle fibers.
to initial length of
Pre Load is directly proportional to End Diastolic Volume. (End Diastolic Volume is the amount of blood remaining in ventricles at the end of diastole). Greater is preload; more is length of muscle fibers. EDV is increased by greater venous return. Therefore more is pre load more is force of myocardial contraction.
FACTORS AFFECTING MYOCARDIAL CONTRACTIBILITY
z z z z
INCREASED BY Catecholamines. Increase in heart rate. Change in heart rhythm. Drugs--- theophylline, caffeine, digitalis. DECREASED BY • Parasympathetic stimulation. • Heart failure. • Hypoxia, acidosis, hypercapnia. • Drugs — barbiturates, quinidine.
FACTORS INCREASING END DIASTOLIC VOLUME • • • • •
Increased venous return. Increased total blood volume. Atrial contractions. Decrease in intra thoracic pressure. Increase pumping action of skeletal muscles.
FACTORS DECREASING END DIASTOLIC VOLUME • • • •
Posture change (standing). Decreased total blood volume. Decrease in compliance of ventricles Increase in intra thoracic pressure.
Methods for determining cardiac output 1. Fick principle Amount of substance taken up by an organ/ unit time = Blood flow x Difference between arterial and venous level Cardiac output ( F ) =
O2 consumption / min AO2 - VO2 =
250 ml/min 5ml%
= 5L/min 2. ECHOCARDIOGRAPHY 3. Indicator Dilution Method
JOIN US FOR FREE: http://www.examville.com
© Examville.com, LLC June 2009
CARDIAC OUTPUT Cardiac output is defined as the amount of blood pumped out by each ventricle per minute into the circulation. Stroke volume – The amount of blood pumped out by each ventricle per beat. Cardiac output = Heart rate x
Stroke volume
= 5-6 L/min It means cardiac output is controlled by heart rate and stroke volume. Factors affecting heart rate Cardiac innervations Cardiovascular centers----- vasomotor centre and vagal centre
Factors affecting stroke volume Stroke volume is affected by contractibility, after load and pre load
FRANK STARLING LAW Force of ventricular contraction is directly proportional muscle fibers.
to initial length of
Pre Load is directly proportional to End Diastolic Volume. (End Diastolic Volume is the amount of blood remaining in ventricles at the end of diastole). Greater is preload; more is length of muscle fibers. EDV is increased by greater venous return. Therefore more is pre load more is force of myocardial contraction.
FACTORS AFFECTING MYOCARDIAL CONTRACTIBILITY
z z z z
INCREASED BY Catecholamines. Increase in heart rate. Change in heart rhythm. Drugs--- theophylline, caffeine, digitalis. DECREASED BY • Parasympathetic stimulation. • Heart failure. • Hypoxia, acidosis, hypercapnia. • Drugs — barbiturates, quinidine.
FACTORS INCREASING END DIASTOLIC VOLUME • • • • •
Increased venous return. Increased total blood volume. Atrial contractions. Decrease in intra thoracic pressure. Increase pumping action of skeletal muscles.
FACTORS DECREASING END DIASTOLIC VOLUME • • • •
Posture change (standing). Decreased total blood volume. Decrease in compliance of ventricles Increase in intra thoracic pressure.
Methods for determining cardiac output 1. Fick principle Amount of substance taken up by an organ/ unit time = Blood flow x Difference between arterial and venous level Cardiac output ( F ) =
O2 consumption / min AO2 - VO2 =
250 ml/min 5ml%
= 5L/min 2. ECHOCARDIOGRAPHY 3. Indicator Dilution Method
Related Documents
Examville.com - Physiology - Cardiac Output
May 2020 6
Cardiac Output
December 2019 6
Cardiac Physiology
May 2020 23
Examvillecom - Physiology -stomach
May 2020 9
10. Cardiac Output Handout
May 2020 5