The human heart heart length, width, and thickness are 12 cm, 8.5 cm, and 6 cm, respectively. In addition, the mean weight of the heart is 280-340 g in males and 230-280 g in females.

1. The Cardiovascular System
Prepared by
Mr.Abhay Rajpoot
HOD (Dep. of Medical Surgical)
abhayrajpoot5591@gmail.com

2. The Cardiovascular System
 Cardiovascularsystem: organ system
that distributes blood to all parts of
thebody
 Major function – transportation,
using blood as thetransport vehicle

3. The Cardiovascular System
 This system carries oxygen, nutrients, cell wastes,
hormones and other substances vital for body
homeostasis to and formcells
 The force to move blood around the body is provided by
the pumping heart and blood pressure

5. The Heart
 The human heart heart length, width, and thickness are 12 cm,
8.5 cm, and 6 cm, respectively. In addition, the mean weight of
the heart is 280-340 g in males and 230-280 g in females.
 It is enclosed within the inferior mediastinum, the medial
cavity of the thorax, and flanked on each side by the
lungs

6. The Heart
 The pointed apex is directed
toward the left hipand restsat
about the fifth intercostal
space
 The broad aspect, or base,
points towardthe right
shoulder and lies beneath
the second rib

7. The Heart
 The heart is enclosed by a double-walled sac called the
pericardium
 The superficial loosely fitted part is called the fibrous
pericardium
 Protects and anchors theheart

8. The Heart

9. The Heart
 Deep to the fibrous
pericardium is the
slippery, two-layer
serouspericardium
 The parietal layer lines
the interior of the
fibrous pericardium

10. The Heart
 The parietal layerattaches to the large arteries leaving
the heart and then makes a U-turn and continues
inferiorly overthe heart surfaceas thevisceral layer, or
epicardium

11. The Heart
 A slippery lubricating fluid is produced by the serous
pericardial membranes which allows the heart to beat
easily in a relative frictionless environment

12. The Heart
 Inflammation of the pericardium, pericarditis,often
results in a decrease in the serous fluid
 The cause the pericardial layers to stick, forming
painful adhesions that interfere with heartmovements

13. The Heart
 The heartwallsarecomposed of three layers:
 1. outerepicardium
 2. myocardium
 3. endocardium

14. The Heart
 The myocardium
consists of thick bundles
of the cardiac muscle
twisted into ring like
arrangements
 This is the layer ofthe
heart that actually
contracts
 Reinforced by dense,
fibrous connectivetissue
(“heart skeleton”)

15. The Heart
 The endocardium is a thin, glistening sheetof
endothelium that lines the heartchambers
 Continuouswith the liningsof the blood vessels
leaving and entering theheart

16. The Heart
 The heart has four hollowchambers:
 2 atria – receivingchambers
 2 ventricles – fillingchambers

17. The Heart
 Blood flows intothe
atria under low
pressure from the
veins, andcontinues
into theventricles

18. The Heart
 The ventricles are thick- walled discharging
chambers
 They are the pumpsof the heart
 When they contract, blood is propelled out of the
heart and into circulation
 The right ventricle forms most of the heart’s anterior
surface
 The left ventricle forms theapex

20. The Heart
 The septum that divides
the heart longitudinally
is the interventricular
septum or theinteratrial
septum based on the
chambers itseparates

21. The Heart
 The heart functionsas a doublepump
 The right sideworksas the pulmonarycircuit pump
 Receives relatively oxygen-poor blood from the veins of
the body through the large superior and inferior vena
cava

22. The Heart

23. The Heart
 The blood then pumps out through the pulmonary
trunk which splits into the left and right pulmonary
arteries
 The pulmonary arteries carry blood to thelungs,
where oxygen is picked up and carbon dioxideis
unloaded
 Oxygen-rich blood drains from the lungs and is
returned tothe leftsideof the heart through the four
pulmonaryveins

24. The Heart
 This circuit is call pulmonarycirculation
 Itsonly function is tocarry blood to the lungs forgas
exchange and then return it to the heart

26. The Heart
 Blood returned to the leftside of the heart is pumped out
of the heart into the aorta
 The systemicarteries branch from theaorta tosupply the
body tissues withblood
 Oxygen-poor blood circulates from the tissues back to
the right atrium via the systemic veins, which empty
their blood into either the superior or inferior vena cava

27. The Heart
 This second circuit, from the left side of the heart
through the body tissuesand back to the right side of
the heart is called systemiccirculation
 Itsuppliesoxygen and nutrient-rich blood toall body
organs
 Because the left ventricle is the systemic pump that
pumps blood overa much longerpathway through the
body, its walls are thicker than those of the right
ventricle
 It is a more powerfulpump

29. The Heart
The heart also has four
valves:
 2 that separatethe
atria from the
ventricles
 2 that separate the
ventricles fromtheir
arteries
 All of these valves
prevent back flow

30. The Heart
 The atrioventricular (AV)
valves are between the atria
and ventricles
 On the left is the bicuspid or
mitral valve
 On the right is the tricuspid
valve

31. The Heart
 When the heart is relaxed and blood is passively filling
its chambers, the AV-valve flaps hang limply into the
ventricles
 As the ventricles contract, they press on the blood in
theirchamber, and the intraventricular pressure rises

32. The Heart
 The semilunar valves guard the bases of the large
arteries leavingthe ventricularchambers
 On the right isthe pulmonary valve
 On the left is theaortic valve
 When the ventricles are contracting these valves are
forced openand flattened againstthe arterial walls
 When the ventricles are relaxed the blood flows back
towards theheart
 This prevents arterial blood fromreentering the
heart

33. The Heart
 The coronary arteries branch from the base of the
aortaand encircle the heart in thecoronary sulcus (AV
groove) at the junctionof theatriaand ventricles

34. The Heart
 The coronary arteries and their major branches are
compressed when the ventricles are contracting
and fill when the heart is relaxed

35. The Heart
 The myocardium is drained by several cardiacveins,
which empty into thecoronary sinus
 The coronary sinus, in turn, empties into the right
atrium

36. The Heart
 When the heart beats rapidly the myocardiumcan
received an inadequate amount of blood
 This can result in crushing chest pain called angina
pectoris

37. The Heart
 Pain due toangina pectoris is
a warningsign
 If angina is prolonged,
oxygen-deprived heartcells
may die forming aninfarct
 The resulting myocardial
infarction is a “heart attack”

39. Heart Physiology
 Although cardiac muscle
can beat independently,
the muscle cells on
different areas of theheart
have differentrhythms
 Atrial cells – 60 bpm
 Ventricular cells –20-40
bpm

40. Heart Physiology
Twosystemsact to regulate heartactivity:
 1. Autonomic nervoussystem – brakes and accelerator
 Acts todecrease or increase heart rate
 2. Intrinsic conduction system (nodalsystem)
 Composed of specialized tissue that is across between
muscle and nervoustissue
 Causes heart muscledepolarization from theatria to
theventricles
 Enforces contraction rate ~ 74bpm

41. Heart Physiology

42. Heart Physiology
Components of the Intrinsic ConductionSystem
include:
 The sinoatrial (SA) node is acrescentshaped node in
the rightatrium
 Theatrioventricular (AV) node is at the junctionof the
atria andventricles
 The atrioventricular (AV) bundle (bundle ofHis)
 Branch bundles in the interventricular septum
 Purkinje fibers which spread with the muscleof the
ventriclewalls

43. Heart Physiology

44. Heart Physiology
 The SA node has the
highest rate of
depolarization in the
wholesystem
 It starts each heartbeat
and sets the pace forthe
whole heart and is
therefore called the
pacemaker

45. Heart Physiology

46. Heart Physiology
 The impulse travels from the SA node through the atria to
the AV node, causing theatria tocontract
 At the AVnode, the impulse is delayed togive the atria
time to finish contracting
 It then passes rapidly through the AVbundle,the bundle
branches, and the Purkinje fibers, causing a “wringing”
contraction of the ventricles that begins at the apex and
moves toward theatria

47. Heart Physiology
 This contraction effectivelyejects blood superiorly into
the large arteries leaving theheart

48. Heart Physiology
 Tachycardia is a rapid heart rate (> 100bpm)
 Bradycardia is a slow heart rate (< 60 bpm)
 Neither condition is pathological, butprolonged
tachycardia may progress tofibrillation

49.  Fibrillation is a rapid,
uncoordinated
shuddering of the heart
muscle
 Fibrillation makes the
heart totallyuselessasa
pump and is a major
cause of death from
heart attacks inadults
Heart Physiology

50. Heart Physiology
 A pacemaker is a small
device, about the sizeof a
half dollar piece, placed
under the skin near the
heart to help control the
heartbeat.
 A pacemaker isimplanted
as part of what's often
referred to as "cardiac
resynchronization
therapy."

51. Heart Physiology
 People may need a pacemaker fora
variety of reasons — mostly due to
one of a group of conditions called
arrhythmias, in which the heart's
rhythm isabnormal
 They can be implantedtemporarily
to treat a slow heartbeat after a
heartattack, surgeryoroverdoseof
medication
 Pacemakers can also be implanted
permanently to correctbradycardia
or to help treat heart failure

52. Cardiac Cycle and Heart Sounds

53. Cardiac Cycle and Heart Sounds
 In a healthy heart, theatria contractsimultaneously
 When theystart torelax, contraction of theventricles
begins
 Systoleand diastole mean heartcontraction and
relaxation respectively

54. Cardiac Cycle and Heart Sounds
 Because most of the pumping work is done by the
ventricles, these terms always refer to the contraction
and relaxation of theventricles unlessotherwisestated

55. Cardiac Cycle and Heart Sounds
 The term cardiac
cycle refers to the
events of one
complete heartbeat,
during which both
atria and ventricles
contract and then
relax

56. Cardiac Cycle and Heart Sounds
 The average heart beats 74 times perminute
 Theaverage length of a cardiac cycle is 0.8 seconds
 Thecardiac cycleoccurs in three majorsteps:
 1. mid-to-latediastole
 2. ventricularsystole
 3. earlydiastole

57. 1. Mid-to-late diastole
 The heart is in complete relaxation
 Pressure in the heart islow
 Blood is flowing passively into and through the atria
and into theventricles from pulmonaryand systemic
circulations

58. 1. Mid-to-late diastole
 The semilunarvalvesareclosed
 The AVvalves are open
 Then theatria contractand force the blood into the
ventricles

59. Cardiac Cycle

60. 2. Ventricular systole
 The pressure within the ventricles increases
rapidly, closing the AVvalves
 When the intraventricular pressure is higher than the
pressure in the large arteries leaving the heart, the
semilunar valves are forced open, and blood rushes
out of theventricles
 The atriaare relaxed, and again are filling with blood

61. Cardiac Cycle

62. 3. Early diastole
 At the end of systole, the ventricles relax, the
semilunarvalvessnapshut, and fora moment the
ventricles are completelyclosed chambers

63. 3. Early diastole
 During early diastole, the intraventricular pressure
drops
 When it drops below the pressure in the atria, the AV
valves are forced open. And the ventricles again begin
to refill rapidly withblood

64. Heart Sounds
 When using a stethoscope, the heart beat usually has
two distinct sounds – “lup” and“dup”
 Thesearecaused by theclosing of the twosets of
valves
 “lup” – AVvalves
 “dup” – semilunarvalves

66. Cardiac Output
 Cardiac Output (CO) is
the amount of blood
pumped out by eachside
of the heart in 1 minute
 It is the product of heart
rate (HR) and stroke
volume (SV)

67. Cardiac Output
 In general, strokevolume increases as the forceof
ventricular contractionincreases
 Let’s look at normal resting heart rateand volume:
 CO = HR x SV
 CO = (74 bpm) x (70 ml perbeat)
 CO = 5180 ml/min

68. Cardiac Output
 A healthy heart pumps
out about 60% of blood
in the ventricles (~70ml)
per heart beat
 The critical factor is how
much the cardiac muscle
cells stretch just before
contracting

69. Cardiac Output
 The important factor
stretching the heart
muscle is venous
return, the amountof
blood entering the
heart and distending
theventricles
 The more the heart
muscles stretch,the
stronger the
contraction

70. Cardiac Output
 If one side of the heart suddenly begins to pump more
blood than the other, the increased venous return to
the opposite ventricle will force it to pump out an
equal amount, thus preventing backup of blood in the
circulation

71. Cardiac Output
 The enhanced squeezing action
of active skeletal muscles from
exercisespeeds upvenousreturn
 Severe blood loss or rapidheart
rate, decreases stroke volume,
creating less venousreturn

72. Factors Modifying Basic Heart Rate
 Heart contraction does not depend on the nervous
system, but itcan bechanged temporarily by the ANS
 It is also modified bychemicals, hormones and ions

73. Neural (ANS) Control
 During times of physical or emotional stress, the
nervesof sympatheticdivision stimulatethe SA and
AVnodes and the cardiacmuscles
 The heart beats morerapidly

74. Neural (ANS) Control
 When the demand declines, the heart adjusts, the
parasympathetic nerves slowand steady the heart rate
 Gives the heart time to recoverand rest

75. Neural (ANS) Control
 In patientswith Congestive Heart Failure (CHF), or
other heartdisease the heart pumpsweakly
 Some medicationscan be used toenhance contractile
force and stroke volume of the heart, improving
cardiac output

76. Congestive Heart Failure

77. Neural (ANS) Control
 Various hormonesand ions havea dramaticeffecton
heartactivity
 Epinephrine – mimics sympathetic nerves,increases
heart rate
 Thyroxine – increase heartrate
 Electrolyte imbalance – prolongedcontractions,
arrhythmias, decreaseoutput

78. Physical Factors
 Resting heart rate is fastest in the fetusand then
graduallydecreases
 Faster heart rate in females thanmales
 High body temperaturealso increase heart rate, Low
body temperature decreases heartrate