Cardiac output (CO) is a measurement of the amount of blood pumped by each ventricle in one minute. To calculate this value, multiply stroke volume (SV), the amount of blood pumped by each ventricle, by heart rate (HR), in contractions per minute (or beats per minute/ bpm). It can be represented mathematically by the following equation: CO = HR × SV REGULATION OF CARDIAC OUTPUT. The regulation of cardiac output is a complex process that involves both INTRINSIC and EXTRINSIC mechanisms. EXTRINSIC REGULATION OF CARDIAC OUTPUT INCLUDES Sympathetic and parasympathetic nervous system Hormones Extrinsic regulation of cardiac output refers to the control of cardiac output by factors outside the heart.  These factors include sympathetic and parasympathetic nerves and hormones such as catecholamine and acetylcholine. Sympathetic nerves increase the heart rate and force of contraction, while parasympathetic nerves decrease the heart rate and force of contraction. HORMONAL REGULATION : Catecholamine and acetylcholine are two hormones that play a role in regulating the cardiac output . Catecholamines, such as adrenaline and noradrenaline, are released by the adrenal glands and sympathetic nerve endings.  They increase the heart rate and force of contraction, thereby increasing the cardiac output .  Acetylcholine, on the other hand, is released by the parasympathetic nerve endings and slows down the heart rate, thereby decreasing the cardiac output. THE INTRINSIC MECHANISMS INCLUDE THE FRANK-STARLING MECHANISM  AND THE IONOTROPIC EFFECT. Frank-Starling law. The law is named after the two physiologists, Otto Frank and Ernest Starling, who first described it in 1918. The Frank-Starling law of the heart is a fundamental principle that describes the relationship between the volume of blood in the heart and the force of contraction of the heart muscle.  In simple terms, the law states that the greater the volume of blood that enters the heart during filling (diastole), the greater the force with which it contracts (systole) and, therefore, the greater the volume of blood that is expelled, within certain limits . Changes in contractility shift the Frank-Starling curve upward or downward. An increase in contractility cause an increase in cardiac output. A decrease in contractility causes a decrease in cardiac output. Ionotropic regulation of cardiac output refers to the control of the force of heart muscle contractions.  This is achieved by altering the movement of ions across cell membranes, particularly in cardiac muscle cells  Positive inotropes are medications that increase the heart’s contractility, which is the force of the heart muscle to push blood out of the heart’s chambers.  IONOTROPIC REGULATION OF CARDIAC OUTPUT : Ionotropic regulation of cardiac output refers to the control of the force of heart muscle contractions. According to a study, the female heart has a larger ejection fraction and beats at a faster rate but generates

1. CARDIAC OUTPUT
BY
MRS.WINCY THIRUMURUGAN

2. • Cardiac output (CO) is a measurement of the
amount of blood pumped by each ventricle in
one minute.
• To calculate this value, multiply stroke volume
(SV), the amount of blood pumped by each
ventricle, by heart rate (HR), in contractions per
minute (or beats per minute/ bpm).
• It can be represented mathematically by the
following equation: CO = HR × SV

6. REGULATION OF CARDIAC
OUTPUT.
The regulation of cardiac output
is a complex process that
involves
both INTRINSIC and EXTRINSI

7. EXTRINSIC REGULATIO
N OF CARDIAC OUTPUT
INCLUDES
• Sympathetic and
parasympathetic
nervous system
• Hormones

8. Extrinsic regulation of cardiac output
refers to the control of cardiac output by
factors outside the heart.
• These factors include sympathetic and
parasympathetic nerves and hormones such
as catecholamine and acetylcholine.
• Sympathetic nerves increase the heart rate and
force of contraction, while parasympathetic
nerves decrease the heart rate and force of
contraction.

11. HORMONAL REGULATION :
• Catecholamine and acetylcholine are two hormones that
play a role in regulating the cardiac output .
• Catecholamines, such as adrenaline and noradrenaline,
are released by the adrenal glands and sympathetic
nerve endings.
• They increase the heart rate and force of contraction,
thereby increasing the cardiac output .
• Acetylcholine, on the other hand, is released by the
parasympathetic nerve endings and slows down the heart
rate, thereby decreasing the cardiac output.

14. THE INTRINSIC MECHANISMS
INCLUDE
THE FRANK-STARLING
MECHANISM
AND
THE IONOTROPIC EFFECT.

15. Frank-Starling law.
The law is named after the two physiologists, Otto Frank and
Ernest Starling, who first described it in 1918.
• The Frank-Starling law of the heart is a fundamental
principle that describes the relationship between the
volume of blood in the heart and the force of contraction
of the heart muscle.
• In simple terms, the law states that the greater the
volume of blood that enters the heart during filling
(diastole), the greater the force with which it contracts
(systole) and, therefore, the greater the volume of blood
that is expelled, within certain limits .

16. Frank-Starling Law Mechanism
The Frank-Starling law mechanism can be defined as ‘an
intrinsic adaptive response which serves to adjust each
ventricular output to its inflow by increasing the force of
contraction of the myocardium proportionally to any increase
in the length of the muscle fibers’, i.e., increase in the volume
of blood entering the heart stretches the walls of the
ventricle, which causes the heart to contract with more force,
like a stretched rubber band, increasing the volume of each
stroke of the heart.

17. • The Frank-Starling mechanism can be seen during periods of physical
exercise with lower work rates. This mechanism works to synchronize
the rate of the blood flow returning to the heart, and the rate of the
blood leaving the heart, without the dependence on external regulation
to make the changes, which can range from 2 liters to 25 liters per
minute.
• The increase in the pressure put upon each fiber increases muscle
contraction due to the formation of actin-myosin compounds in the
fibers and the activation of calcium ions, which depends upon the
length of each muscle unit.
• Maximum force is exerted by the heart when the muscle fibers have an
original length of 2.2 micrometers. Fibers which have longer or shorter
lengths produce lesser force.

19. Changes in contractility shift the Frank-
Starling curve upward or downward. An
increase in contractility cause an
increase in cardiac output. A decrease
in contractility causes a decrease in
cardiac output.

20. IONOTROPIC REGULATION OF CARDIAC
OUTPUT :
Ionotropic regulation of cardiac output refers to
the control of the force of heart muscle contractions.
 This is achieved by altering the movement of ions across
cell membranes, particularly in cardiac muscle cells
 Positive inotropes are medications that increase the
heart’s contractility, which is the force of the heart muscle
to push blood out of the heart’s chambers.
These medications allow the heart to squeeze tighter and
make each heartbeat more effective at pushing blood
through the body, improving cardiac output .
 Intrinsic inotropic stimulation of the heart is central to the
regulation of cardiovascular function, and exogenous
inotropic therapies have been used clinically for decades.

23. FACTORS MAINTAINING CARDIAC
OUTPUT

28. According to a study, the female
heart has a larger ejection
fraction and beats at a faster
rate but generates a smaller
cardiac output compared to the
male heart

29. PATHOLOGICAL
FACTORS