The physiology of the Heart and blood vessels. the different actions of the heart and also the properties of the cardiac muscles.

1. Cardiovascular physiology
By: Amen Ullah
Lecturer Surgical
KMU-IPMS
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2. Course outlines
I. Introduction to cardiovascular system
II. Cardiovascular System
III. Heart
IV. Actions of The Heart
V. Blood Vessels
VI. Properties of Cardiac Muscle
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3. Cardiovascular system
• It includes heart and blood vessels.
• Heart pumps blood into the blood vessels.
• Blood vessels circulate the blood throughout
the body.
• Blood transports nutrients and oxygen to the
tissues and removes carbon dioxide and waste
products from the tissues
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5. Responsibilities of
cardiovascular system
–Pumping blood to the body tissues and cells
–Supplying oxygen and nutrients to tissues
and cells
–Removing carbon dioxide and other waste
products of metabolism from tissues and
cells
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6. HEART
Right Side
Left Side
Septa
Layers of The Wall
 Pericardium
Myocardium
Endocardium
Valves
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7. ACTIONS OF THE HEART
1. Chronotropic Action (frequency)
o Tachycardia
o Bradycardia
2. Inotropic Action (force of contraction)
o May be +ive or -ive
3. Dromotropic Action (conduction of impulses)
o May be +ive or –ive
4. Bathmotropic Action (Excitability of cardiac muscle)
May be +ive or -ive
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8. BLOOD VESSELS
 Arterial System
 Venous System
 Complications in Blood Vessels
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9. Blood vessels
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10. Properties of Cardiac Muscle
• Excitability
• Rhythmicity
• Conductivity
• Contractility
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11. Excitability
• Excitability is defined as the ability of a living
tissue to give response to a stimulus.
• In all the tissues, initial response to a stimulus
is electrical activity in the form of action
potential.
• It is followed by mechanical activity in the
form of contraction, secretion, etc.
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12. Rhythmicity
• Rhythmicity is the ability of a tissue to produce its own
impulses regularly.
• It is also called autorhythmicity or self-excitation.
Property of rhythmicity is present in all the tissues of
heart.
• However, heart has a specialized excitatory structure,
from which the discharge of impulses is rapid.
• This specialized structure is called pacemaker.
• From here, the impulses spread to other parts through
the specialized conductive system.
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13. Pacemaker
• Pacemaker is the structure of heart from
which the impulses for heartbeat are
produced.
• It is formed by the pacemaker cells called P
cells.
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14. Sinoatrial Node
• Sinoatrial (SA) node is a small strip of modified cardiac muscle,
situated in the superior part of lateral wall of right atrium, just
below the opening of superior vena cava.
• The fibers of this node do not have contractile elements.
• These fibers are continuous with fibers of atrial muscle, so that the
impulses from the SA node spread rapidly through atria.
• Other parts of heart such as atrioventricular (AV) node, atria and
ventricle also can produce the impulses and function as
pacemakers.
• Still, SA node is called the pacemaker because the rate of
production of impulse (rhythmicity) is more in SA node than in
other parts.
• It is about 70 to 80/minute
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15. SA Node
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16. CONDUCTIVITY
• Human heart has a specialized conductive
system,
through which impulses from SA node are
transmitted
to all other parts of the heart
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17. Components of Conductive System
in Human Heart
• 1. AV node
2. Bundle of His
3. Right and left bundle branches
4. Purkinje fbers.
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18. Conductive System of Human Heart
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19. CONTRACTILITY
• Contractility is ability of the tissue to shorten
in length (contraction) after receiving a
stimulus.
• Various factors affect the contractile
properties of the cardiac muscle.
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20. Heart contractility curve
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21. ALL-OR-NONE LAW
• According to all-or-none law, when a stimulus is applied,
whatever may be the strength, the whole cardiac muscle
gives maximum response or it does not give any response
at all.
• Below the threshold level, i.e. if the strength of stimulus is
not adequate, the muscle does not give response.
• All-or-none law is demonstrated in the quiescent (quiet)
heart of frog. Heart is made quiescent by applying the frst
Stannius ligature in between the sinus venosus and right
auricle.
• Ventricle is stimulated by placing the electrode at
the base of ventricle.
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22. • REFRACTORY PERIOD
Refractory period is the period in which the
muscle does not show any response to a
stimulus.
• It is of two types:
1. Absolute refractory period
2. Relative refractory period.
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23. Absolute Refractory Period
• Absolute refractory period is the period during which
the muscle does not show any response at all,
whatever may be the strength of the stimulus.
• It is because, the depolarization occurs during this
period. So, a second depolarization is not possible.
Relative Refractory Period
• Relative refractory period is the period during which
the muscle shows response if the strength of stimulus
is increased to maximum.
• It is the stage at which the muscle is in repolarizing
state.
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