Book contents
- Frontmatter
- Contents
- List of Abbreviations
- Dedication
- Preface
- A Change in Posture
- Acid-Base
- Action Potentials
- Adrenal Cortex I
- Adrenal Cortex II – Clinical Disorders
- Adrenal Medulla
- Arterial Pressure
- Autonomic Nervous System (ANS)
- Carbon Dioxide Transport
- Cardiac Cycle
- Cardiac Output (CO)
- Cell Signalling
- Cerebrospinal Fluid (CSF) and Cerebral Blood Flow
- Colon
- Control of Ventilation
- Coronary Circulation
- Fetal Circulation
- Glomerular Filtration and Renal Clearance
- Immobilization
- Liver
- Mechanics of Breathing I – Ventilation
- Mechanics of Breathing II – Respiratory Cycle
- Mechanics of Breathing III – Compliance and Elastance
- Mechanics of Breathing IV – Airway Resistance
- Microcirculation I
- Microcirculation II
- Micturition
- Motor Control
- Muscle I – Skeletal and Smooth Muscle
- Muscle II – Cardiac Muscle
- Nutrition: Basic Concepts
- Pancreas I – Endocrine Functions
- Pancreas II – Exocrine Functions
- Potassium Balance
- Proximal Tubule and Loop of Henle
- Pulmonary Blood Flow
- Renal Blood Flow (RBF)
- Respiratory Function Tests
- Small Intestine
- Sodium Balance
- Sodium and Water Balance
- Starvation
- Stomach I
- Stomach II – Applied Physiology
- Swallowing
- Synapses I – The Neuromuscular Junction (NMJ)
- Synapses II – Muscarinic Pharmacology
- Synapses III – Nicotinic Pharmacology
- Thyroid Gland
- Valsalva Manoeuvre
- Venous Pressure
- Ventilation/Perfusion Relationships
Cardiac Output (CO)
Published online by Cambridge University Press: 06 January 2010
- Frontmatter
- Contents
- List of Abbreviations
- Dedication
- Preface
- A Change in Posture
- Acid-Base
- Action Potentials
- Adrenal Cortex I
- Adrenal Cortex II – Clinical Disorders
- Adrenal Medulla
- Arterial Pressure
- Autonomic Nervous System (ANS)
- Carbon Dioxide Transport
- Cardiac Cycle
- Cardiac Output (CO)
- Cell Signalling
- Cerebrospinal Fluid (CSF) and Cerebral Blood Flow
- Colon
- Control of Ventilation
- Coronary Circulation
- Fetal Circulation
- Glomerular Filtration and Renal Clearance
- Immobilization
- Liver
- Mechanics of Breathing I – Ventilation
- Mechanics of Breathing II – Respiratory Cycle
- Mechanics of Breathing III – Compliance and Elastance
- Mechanics of Breathing IV – Airway Resistance
- Microcirculation I
- Microcirculation II
- Micturition
- Motor Control
- Muscle I – Skeletal and Smooth Muscle
- Muscle II – Cardiac Muscle
- Nutrition: Basic Concepts
- Pancreas I – Endocrine Functions
- Pancreas II – Exocrine Functions
- Potassium Balance
- Proximal Tubule and Loop of Henle
- Pulmonary Blood Flow
- Renal Blood Flow (RBF)
- Respiratory Function Tests
- Small Intestine
- Sodium Balance
- Sodium and Water Balance
- Starvation
- Stomach I
- Stomach II – Applied Physiology
- Swallowing
- Synapses I – The Neuromuscular Junction (NMJ)
- Synapses II – Muscarinic Pharmacology
- Synapses III – Nicotinic Pharmacology
- Thyroid Gland
- Valsalva Manoeuvre
- Venous Pressure
- Ventilation/Perfusion Relationships
Summary
1. What is the definition of the CO?
This is defined as the product of the heart rate and the stroke volume.
2. Give a normal resting value for the CO.
5–6 Lmin−1.
3. How do the outputs of the two ventricles compare to one another?
In the normal state, the outputs of both ventricles are essentially equal – both being 5–6 Lmin−1.
4. Which factors influence the stroke volume?
Preload
Afterload
Myocardial contractility
Heart rate
5. What determines the preload?
This is determined by the venous return to the heart. The amount of venous return itself depends on the difference between the systemic filling pressure (driving blood back to the heart) and the central venous pressure (CVP) (working against the venous return).
6. Define the afterload. What is this analogous to, in simple terms?
This is the ventricular wall tension that has to be generated in order to eject blood out of the ventricle. It is analogous to the arterial pressure. An increase in the CO causes a rise in the arterial pressure (afterload). This in turn, has a negative feedback effect on the output. Since more energy is consumed generating a high enough pressure to overcome a high arterial pressure, the resulting stroke volume is less – reducing the output in subsequent beats.
7. What happens to the Frank-Starling curve of the heart when the myocardial contractility is increased?
There is an upwards shift of the curve, so that the stroke volume is higher for any given end diastolic volume.
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- Applied Surgical Physiology Vivas , pp. 37 - 39Publisher: Cambridge University PressPrint publication year: 2004