The document discusses the anatomy and physiology of the heart. It describes the heart's location and coverings including the pericardium. It details the heart chambers including the atria which receive blood and the ventricles which pump blood out. It explains the pathway of blood flow through the two circuits, pulmonary and systemic. It outlines the heart valves and electrical conduction system. Finally, it discusses the cardiac cycle and factors regulating cardiac output such as preload, contractility, and afterload.

1. Anatomy & physiology
of the heart

4. Heart Anatomy
 Size, Location, and Orientation
 Enclosed in the mediastinum
 Base (posteriorsuperior portion)
and Apex (inferioranterior portion)

5. Heart Anatomy
 Coverings
 Pericardium
 protects the heart
 anchors the heart to
surrounding structures such as
the diaphragm and the great
vessels
 prevents overfilling of the heart
with blood

6. Heart Anatomy
Coverings
 pericardial cavity contains a film of
serous fluid
 pericarditis: inflammation of the
pericardium which may lead to
adhesions between the layers or
the buildup of fluid in the pericardial
cavity (cardiac tamponade)

7. Heart Anatomy
 Heart Wall
 Epicardium
 Myocardium
 bulk of the heart consisting
mainly of cardiac muscle

8. Heart Anatomy
 Heart Wall
 Endocardium
 simple squamous epithelium
and a thin CT layer that lines the
heart chambers and valves and
is continuous with the
endothelial lining of the blood
vessels

9. Heart Anatomy
 Chambers
 Atria
 Features
 small, thin-walled chambers
 Functions
 receiving chambers for blood
returning to the heart from the
circulation
 push the blood into the adjacent
ventricles.

10. Heart Anatomy
 Chambers
 Atria
 Receive blood from
 right side
 Superior and Inferior Vena Cava
 Coronary Sinus (draining the
myocardium)
 left side
 Pulmonary Veins

11. Heart Anatomy
 Chambers
 Ventricles
 Features
 make up most of the mass of the
heart
 the walls of the left ventricle are
3X thicker than those of the right

12. Heart Anatomy
 Chambers
 Ventricles
 Functions
discharging chambers of the heart
propel blood to Pulmonary Trunk (right
ventricle), Aorta (left ventricle)

14. Heart Anatomy
 Pathway of Blood Through the Heart
 Pulmonary Circuit
 functions strictly as gas exchange
 the right side of the heart is the
pulmonary circuit pump
 this is a short, low-pressure circuit

15. Heart Anatomy
 Pathway of Blood Through the Heart
 Systemic Circuit
o functions as both gas and nutrient
exchange
o the left side of the heart is the
systemic circuit pump
o this is a long, high-resistance
pathway through the entire body

16. Heart Anatomy
 Heart Valves
 These enforce the one-way flow of
blood through the heart
 The valves open and close in response
to differences in blood pressure on
their two sides

17. Heart Anatomy
 Heart Valves
 Atrioventricular Valves
 the valves close when the ventricular
pressure increases and forces blood
against the valve flaps
 Tricuspid (right side)
 Bicuspid (Mitral) (left side)

18. Heart Anatomy
 Heart Valves
 Semilunar Valves
 located between the ventricles and
the large arteries
 these open when the pressure
produced by the contracting ventricle
exceeds that in the artery and close
when the arterial pressure exceeds
the pressure produced by the
relaxing ventricle
 Pulmonary (right side)
 Aortic (left side)

20. Coronary Circulation
 Coronary Arteries
 the coronary arteries arise from the
base of the aorta and actively deliver
blood only when the heart is relaxed
 the heart is 0.5% of body weight and
receives 5% of the body's blood supply
(most to the left ventricle)

21. Coronary Circulation
 Coronary Arteries
 left main coronary artery
 left anterior descending artery:
serves the interventricular septum
and anterior walls of both ventricles
 circumflex artery: serves the left
atrium and posterior wall of the left
ventricle

22. Coronary Circulation
Coronary Arteries
 Right main coronary artery
 posterior descending artery: serves the
posterior walls of both ventricles
 marginal artery: lateral wall of the right
side of the heart
 Cardiac Veins follow arteries and join at
the Coronary Sinus which empties blood
into the right atrium

24. Heart Physiology
 Electrical Events
 Intrinsic Conduction System of the
Heart
 the ability of cardiac muscle to
depolarize and contract is intrinsic
(no nervous stimulation is required)
 nerve impulses can alter the basic
rhythm of heart activity set by
intrinsic factors

25. Heart Physiology
 Electrical Events
 Action Potential Generated by
Autorhythmic Cells
 Sequence of Excitation
o Sinoatrial Node
o Atrioventricular Node
o Atrioventricular Bundle (bundle of
His)
o Bundle Branches
o Purkinje Fibers

26. Heart Physiology
 Electrical Events
 Extrinsic Innervation of the Heart
 fibers of autonomic nervous system
accelerate or inhibit the basic rate of
heartbeat set by the intrinsic
conduction system

27. Heart Physiology
 Electrical Events
 Electrocardiography
 electrical currents generated and
transmitted through the heart spread
throughout the body and can be
monitored
 the graphic recording of electrical
changes during heart activity is
called an electrocardiogram (ECG or
EKG)

28. Heart Physiology
 Electrical Events
 Electrocardiography
 the ECG consists of series of three
waves
o P Wave: atrial depolarization starting
at the SA node
o QRS Complex: ventricular
depolarization

29. Heart Physiology
 Electrical Events
 Electrocardiography
o P-R (P-Q) interval: time from the
beginning of atrial excitation to
the beginning of ventricular
excitation and includes the
contraction of the atria and the
passage of the depolarization
wave through the rest of the
conduction system

30. Heart Physiology
Electrical Events
 Electrocardiography
oT Wave: ventricular repolarization
oQ-T interval: time from the beginning of
the ventricular depolarization through
their repolarization and includes the
contraction of the ventricles

31. Heart Physiology
 Mechanical Events: The Cardiac Cycle
 Terms
 Systole: contraction period of heart
activity
 Diastole: relaxation period of heart
activity

32. Heart Physiology
 Mechanical Events: The Cardiac
Cycle
 Cardiac Cycle
o pressure in the heart is low and
the blood is returning passively
(70% of ventricle filling occurs)
o atria depolarize (P wave) and
contract and force the remaining
30% of the blood into the
ventricles
o the atria relax and remain in
diastole through the rest of the
cycle

33. Heart Physiology
 Mechanical Events: The Cardiac
Cycle
o the ventricles depolarize (QRS
complex)
o ventricles begin their contraction
o ventricular pressure rises rapidly
and the AV valves close
o as ventricular pressure rises
above arterial pressure the
semilunar valves open and the
ventricles empty during the

34. Heart Physiology
 Mechanical Events: The Cardiac Cycle
o ventricular systole ends with the
repolarization of the ventricles (T
wave)
o ventricles relax and ventricular
pressure drops
o semilunar valves close
o the atria have been filling with blood
since ventricular systole and when
the atrial pressure exceeds the
ventricular pressure the AV valves
open ventricular filling begins again

35. Heart Physiology
 Cardiac Output
 General
 cardiac output is the amount of
blood pumped out by each ventricle
in 1 minute and is the product of
heart rate (HR) and stroke volume
(SV)
 stroke volume is the volume of blood
pumped out by one ventricle with
each beat and is the difference
between end diastolic volume (EDV)
and the end systolic volume (ESV)

36. Heart Physiology
 Cardiac Output
 Regulation of Stroke Volume
 Preload: Degree of Stretch
 affected by the EDV and operates
intrinsically
 Frank Starling Law of the Heart:
The greater the degree of stretch
of cardiac muscle fibers the
greater the force of contraction
and the greater the stoke volume

37. Heart Physiology
 Cardiac Output
 resting cardiac fibers are normally
shorter than the optimal length
and stretching them (increasing
EDV) produces dramatic
increases in contractile force
 anything that increases the
volume or speed of venous return
(slow heart rate or exercise)
increases EDV which increases
the force of contraction which
increases stroke volume

38. Heart Physiology
 Cardiac Output
 Contractility
 affects the ESV and are extrinsic
factors that increase the
contractile strength of heart
muscle
 many chemicals enhance
contractility (positive inotropic
agents)

39. Heart Physiology
 Cardiac Output
 Afterload: Back Pressure
 affects the ESV
 the pressure exerted on the aortic
(80 mm Hg) and pulmonary (20
mm Hg) valves by arterial blood
 important in people with
hypertension where ESV is
increased and stroke volume is
reduced

40. SA
AV