1. THE
CARDIOVASCULAR
SYSTEM
Presented by:
Jeffrey Giles RN BSN

2. Location of the heart
Size:
• Size of a fist and weighs
less than 1 lb.
Location:
• Mediastinum
• Rests on the diaphragm
• 2/3 of the heart lies left of
the midline
• Apex – directed anteriorly,
inferiorly, and left
• Base – posteriorly,
superiorly, and left

3. Outer Layers of the Heart
Pericardium:
• Double-layered sac that
anchors and protects
heart
Parietal pericardium:
• membrane around
heart’s cavity
Visceral pericardium:
• membrane on heart’s
surface

4. Pericardium
Pericardium
• The membrane that surrounds and protects the heart
• Two Main Parts:
• Fibrous Pericardium
• Serous Pericardium

5. Outer Layers of the Heart

6. Pericardium
Fibrous Pericardium:
• Superficial layer
• Composed of tough inelastic dense irregular
connective tissue
• Resembles a bag that rests on and attaches to the
diaphragm
• Prevents over stretching of the heart
• Provides protection from the mediastinum

7. Pericardium
Serous Pericardium
• Deeper and thinner layer of the pericardium
Two Layers:
• Parietal Layer
• Visceral Layer (aka: epicardium)
• Adheres to the surface of the heart
Pericardial Fluid
• Between parietal and visceral layers
• Thin film fluid
• Slippery secretion of the pericardial cells provides lubrication
for the heart as it expands and contracts
• Prevents pericardial friction

8. Parietal pericardium
• Part of the
Serous
Pericardium
• Outer layer of
the serous
pericardium
• In contact with
the superfical
layer called –
the fibrous
pericardium

9. Layers of the Heart Wall
3 Layers of the Heart Wall
Superficial to deep:
1. Epicardium
2. Myocardium
3. Endocardium

10. Layers of the Heart Wall
Epicardium:
• Outer most layer
• Transparent surface layer
of heart (outside)
• Remember:
• this is also the visceral
layer of the pericaridum
• Composed of delicate,
smooth slippery connective
tissue

11. Layers of the Heart Wall
Myocardium
• (myo=muscle)
• Cardiac Muscle Tissue
• Makes up the bulk of the heart
• Responsible for heart contraction – pumping action
• Striated like skeletal muscle
• Involuntary action – autonomic nervous system
Summary:
• The muscle tissue of the HEART. It is composed of striated,
involuntary muscle cells (MYOCYTES) and connected to
form the contractile pump to generate blood flow

12. Layers of the Heart Wall
Endocardium
• (Endo=within)
• Provides the smooth lining for the chambers of the heart
• Covers the values of the heart
• Continuous with the blood vessels of the heart
The endocardium is
the innermost layer of
tissue that lines the
chambers of the
heart. Its cells are
similar to the
endothelial cells

13. Layers of the Heart Wall

14. CHAMBERS OF THE
HEART

15. Chambers of the Heart
4 Chambers of the Heart:
• Left atrium (LA)
• Right atrium (RA)
• Left ventricle (LV)
• Right ventricle (RV)

16. Chambers of the Heart
Atria
• (atria = entry hall)
• Two superior chambers (Left and Right Atria)
• Blood returns to the heart into the atria
Right Atrium Left Atrium
Receives Un-oxygenated
(O2-) Blood From:
• Superior Vena Cava
• Inferior Vena Cava
Receives Oxygenated
(O2+) Blood From:
• Pulmonary Veins

17. Chambers of the Heart
The Atria:
• Upper portion of heart (the base)
• Holding chambers for returning
blood
• Small, thin walled
• Less muscular than the ventricles
• Contracts to push blood into
ventricles
Interatrial septum:
separates right and left atria

18. Chambers of the Heart
Ventricles
• Lower portion of the heart (the apex)
• Pumping chambers
• The ventricles contract to push blood out of the heart
• Large muscular chambers that collect and expel blood received from
an atrium
• Thick muscular, strong walled
• Contract forcefully to propel blood out of heart
Interventricular septum:
separates right and left ventricles

19. Chambers of the Heart
Right Ventricle
• Pumps Deoxygenated
blood received from the
body via the Right Atrium
into the Pulmonary
artery
• The Pulmonary Artery is
the passageway for
deoxygenated blood to
travel into the lungs to
receive oxygen
Left Ventricle
• Pumps Oxygenated
blood into the systemic
circulation through the
Aorta
• Some blood from the
aorta flows into the
coronary arteries to
supply the heart with
oxygenated blood
• Left ventricle works
harder than the
right…pumps blood
throughout the system

20. Chambers of the Heart

21. VALVES OF THE HEART

22. Valves of the Heart
• 4 values of the heart
• 2 on the right side / 2 on the left side
• Atrioventricular valves (AV):
• Between atria and ventricles
• 2 Atrioventticular (One Right: Tricuspid / One Left:
Bicuspid)
• Semilunar valves:
• Pulmonary: base of pulmonary trunk (right side)
• Aortic: base of aorta (left side)
• Valves are structures that permit One Way Blood Flow

23. Valves of the Heart
Tricuspid Valve:
• Right Side of the Heart
• One of two atrioventricular valves, which separates the atria
and ventricular chambers -
• Separates Right Atrium from Right Ventricle
• Blood passes through the tricuspid valve from the right atrium
to the right ventricle
• Tri - has three leaflets and three papillary muscles
• Opens during atria systole (contraction) permitting blood to
enter the right ventricle

24. Valves of the Heart
Pulmonary Valve (aka: Pulmonic Valve)
• Right side of the heart
• Semilunar value (semi = half, luna moon shaped), which
has three cusps
• Pulmonary valve opens in ventricular systole, when the
pressure in the right ventricle rises above the pressure in
the pulmonary artery
• Resides between right ventricle the pulmonary artery
• Deoxygenated blood is pumped from the right ventricle
through the Pulmonary value and the pulmonary artery to
the lungs to receive oxygen

25. Valves of the Heart
• Pulmonary Valve

26. Valves of the Heart
Bicuspid Valve (Aka: Mitral Valve)
• Left side of the Heart
• Atrioventricular valve – separates the atria and
ventrriculuar chambers
• During diastole, the mitral valve opens as a result of
increased pressure from the left atrium
• Opening facilitates the passive flow of blood from the left
atria into the left ventricle
• The apical pulse is heard from the bicuspid valve closing

27. Valves of the Heart
Chordae tendineae
• On the bicuspid valve chordae tendinea are attached to
both leaflets
• Thus, when the left ventricle contracts, the intraventricular
pressure forces the valve to close
• The cordea tendineae are the tendons that keep the
leaflets together and prevent the valve from opening in
the wrong direction (regurgitation – back into the atria)

28. Valves of the Heart
Bicuspid Valve OPEN
• Blood flows from LA into
LV.
• Aortic semilunar valve is
closed.
• Tension on chordae
tendineae is low.
Bicuspid Valve CLOSED
• Blood flows from LV into
aorta.
• Aortic semilunar valve is
open.
• Tension on chordae
tendineae is high.

29. Valves of the Heart
Aortic Valve
• Semi-lunar valve
• Open when pressure in the ventricles exceeds pressure in the
arteries
• During ventricular systole:
Pressure rises in the left ventricle
When the pressure in the left ventricle rises above the pressure
in the aorta, the aortic valve opens
Blood exits the left ventricle and is pumped into the aorta
When ventricular systole ends, pressure in the left ventricle
rapidly drops. When the pressure in the left ventricle decreases,
the aortic pressure forces the aortic valve to close

30. Valves of the Heart

31. CIRCULATION

32. Circulation
Pulmonary circuit:
• Right side of the heart:
• Oxygen poor blood is received from the body
• Blood is O2 poor, CO2 rich
• Blood is transported from the Right Side of the
Heart (right atrium and right ventricle) to the
lungs via the Pulmonary Artery, where blood
receives oxygen and release CO2

33. Circulation
Pulmonary Circuit
Right Atrium:
• receives blood from 3 sources:
• Superior vena cava
• Inferior vena cava
• Coronary Sinus
Superior vena cava:
• Returns blood from above diaphragm (head, neck, thorax,
upper limbs)
Inferior vena cava:
• Returns blood from below diaphragm cavity and lower limbs
coronary sinus:
• Returns blood from myocardium

34. Circulation
Pulmonary Circuit
Right Ventricle
• Receives oxygen poor blood from the right atrium via the
tricuspid valve (atrioventricular valve)
• Opens into the pulmonary trunk
Pulmonary trunk:
• Splits into right and left pulmonary arteries
Pulmonary arteries:
• Transports O2 poor blood away from heart to lungs to
receive oxygen and release Co2

35. Circulation
Pulmonary Circuit Summary
• Pulmonary circulation is the half portion of the
cardiovascular system which carries oxygen-depleted blood
away from the heart, to the lungs, and returns oxygenated
(oxygen-rich) blood back to the heart (left atrium).
• Pulmonary circulation the flow of blood from the right
ventricle through the pulmonary artery to the lungs, where
carbon dioxide is exchanged for oxygen, and back through
the pulmonary vein to the left atrium.

36. Circulation
Systemic circuit
Left Side of the Heart
• Pumps oxygenated blood from the left ventricle of
the heart to body (organs, tissues, muscles)
• Blood is O2 rich

37. Circulation
Systemic circuit
Left Atrium:
• There are 4 openings caused by the pulmonary veins
returning oxygenated blood from the lungs
Left Ventricle:
• Receives O2+ blood from left atrium via the mitral valve aorta
• Thicker myocardial walls than the right ventricle
• Contracts more forcefully to eject blood against systemic
pressure (systemic vascular resistance)
• Pumps blood into the aorta via the semi-lunar aortic vlavles
Aorta:
carries blood from left ventricle to body (system)

38. Circulation
1. Right Atrium - receives O2- blood from body
2. Tricuspid valve – opens and permits blood to flow into the
Right ventricle
3. Right Ventricle - contracts and pumps blood through the
Pulmonary semilunar valve to the Pulmonary trunk
4. O2- blood travels through the Pulmonary arteries to the
lungs
5. Lungs – oxygenate blood
6. Pulmonary veins return oxygenated blood to the Left
Atrium
7. Left Atrium – receives O2+ blood from the lungs
8. Bicuspid valve – valve opens and permits blood to drain
into the Left Ventricle
9. Left Ventricle copntracts and pumps oxygenated blood to
the - Aortic semilunar valve
10. Aorta
11. Body

39. Circulation
• Pulmonary and
Systemic
Circulation
Systems

40. Circulation

41. Circulation

42. Coronary Circulation
Coronary Arteries:
• Supply the myocardium with oxygenated blood
• Originate from base of aorta
• While the heart is contracting little blood flows
through the coronary arteries, squeezed shut due
to myocardial expansion
• Blood is received to the myocardia when the heart
relaxes
• Blockage of the coronary arties from thrombosis
result in ischemia and cause the heart muscle
cells (myocardia) to die

43. Coronary Circulation
Two Coronary Arties:
Right Coronary Artery
• Marginal Branch
• Supplies the myocardium of the right ventricle with
oxygenated blood
Left Coronary Artery
• Left Anterior Descending (LAD)
• Circumflex Branch
• Supplies oxygenated blood to the myocardial walls of
the Left Ventricle and Atrium

44. Coronary Circulation
Coronary Veins
Coronary Sinus
• Most blood drains from the coronary sinus located in the
coronary sulcus on the posterior side of the heart
• Veins that carry deoxygenated blood to the coronary sinus:
• Great cardiac vein
• Middle cardiac vein
• Small cardiac vein
• Anterior cardiac vein

45. Coronary Circulation

46. CARDIAC MUSCLE

47. Cardiac Muscle
Structural Proteins:
• Like skeletal muscle, the primary structural proteins of
cardiac muscle are actin and myosin, however, in contrast
to skeletal muscle, cardiac muscle cells may be branched
instead of linear and longitudinal.
• T-Tubules
• Another difference between cardiac muscle and skeletal
muscle is that the T-tubules in the cardiac muscle are
larger, broader and run along the Z-Discs.
• There are also fewer T-tubules in comparison with
skeletal muscle

48. Cardiac Muscle
Intercalated discs
• Junctions between cardiac muscles
• Contain many gap junctions which permit one cardiac
muscle fiber to touch the cytoplasm of another
• Intercalated discs also support the rapid spread of action
potentials and the synchronized contraction of the
myocardium
Gap Junctions
• Allow muscle action potential to conduct from one cardiac
muscle fiber to another

49. Cardiac Muscle
Calcium
• In contrast to skeletal muscle, cardiac muscle requires
extracellular calcium ions for contraction to occur
• Like skeletal muscle, the initiation and upshoot of the
action potential in ventricular muscle cells is derived from
the entry of sodium ions across the sarcolemma
• However, an inward flux of extracellular calcium ions
through sustains the depolarization of cardiac muscle
cells for a longer duration
• This allows for proper filling of the ventricles with blood
from the atria

50. Cardiac Muscle
Autorhythmic fibers
• The myocardium contract without impulses sent from the
nervous system
• This ability is automaticity (self excitable)
• The source of electrical activity in the heart is conducted by a
network of specialized cardiac muscle fibers that generate
action potentials to trigger heart contractions
Pacemaker –
• establishes rhythm of electrical stimulation
Conduction system –
• Ensures that cardiac chambers are stimulated in a
coordinated manner

51. Cardiac Muscle

52. THE
CONDUCTION SYSTEM

53. The Conduction System
Sinoatrial Node (SA Node)
• The 1st major node
• The pacemaker of the heart
• Located in the Right Atrium
• Superior wall of the Right Atrium
• Excitation of the heart begins with the SA Node
• Composed of a mass of pacemaker potential
auto-rhythmic myocardial cells
• Sets the pace of heart contractions
• (60 – 100 BPM)

54. The Conduction System
Artioventricular Node (AV Node)
• The 2nd major node
• Action potential are received from the SA Node via gap
junctions and arrive at the AV node
• The AV node is an area of specialized tissue between the
atria and the ventricles
• A wave of excitation spreads out from the sinoatrial node
through the atria along specialized conduction channels to
activate the AV node
• The SA node delays impulses by approximately 0.12s
• This delay in the cardiac pulse ensures that the atria have
ejected their blood into the ventricles
• 40 – 60 BPM

55. The Conduction System
Bundle of His
• 3rd major conduction location
• A collection of heart muscle cells specialized for electrical
conduction
• Transmits the electrical impulses received from the AV node
• The Bundle of His is located between the atria and the
ventricles
• Splits into the left and right bundle branches
• Only site where action potentials conduct from the atria and
ventricles
• From the Bundle of His the impulse then is transmitted to
the Purkinje fibers

56. The Conduction System
Purkinje fibers
• Specialized muscle fibers in the heart that relay
impulses from the atrioventricular bundle to the
ventricles
• During the ventricular contraction portion of the
cardiac cycle, the Purkinje fibers carry the
contraction impulse from both the left and right
bundle branch to the myocardium of the ventricles
• This causes the muscle tissue of the ventricles to
contract

57. The Conduction System
1. SA node
2. AV node (atrioventricular)
3. AV bundle
4. Right and Left Bundle branches
5. Purkinje fibers

58. The Conduction System

59. ACTION POTENTIAL

60. Cardiac Action Potentials
Action Potentials in Cardiac Muscle
• Caused by the SA Node
Depolarization phase:
• Na+ channels open very fast
• Ca2+ channels open
Plateau phase:
• Period of sustained depolarization, caused by the opening
of the Ca2+ channels opening
• Na+ channels close
• Some K+ channels open
• Ca2+ channels remain open

61. Cardiac Action Potentials
Repolarization phase:
- K+ channels are open
- Ca2+ channels close
• Plateau phase prolongs action potential by keeping
Ca2+ channels open.
• In skeletal muscle action potentials take 2 msec, in
cardiac muscle they take 200-500 msec.

62. Cardiac Action Potentials

63. ELECTROCARDIOGRAM

64. ECG
P wave:
• Atria depolarization
• Represents the electrical impulse originating the SA node and
spreading through the atria
• This is called Arterial Depolarization
• 0.11 seconds ( < 3 small boxes)
• Presence of P wave signifies that the impulse originated in
the SA node
QRS complex:
• Ventricular depolarization
T wave:
• Repolarization of ventricles

65. ECG
QRS complex:
• Ventricular depolarization
• Ventricles contract
• QRS complex measures < 0.12 seconds
• If the QRS complex is prolonged conduction is impaired
within the ventricles.
• This can occur with bundle branch blocks

66. ECG
T Wave
• Ventricular Repolarization
• Ventricles Relax
P-Q Interval
• Time required for the action potential to travel through the
atria, AV node, Bundle Branches, Perkinje fibers
S-T Segment
• Time when the ventricular myocardial fibers are
depolarized during the plateau period

68. Cardiac Cycle
Atrial Systole
• Depolarization of the SA node causes systole (contraction)
– (P wave)
Ventricular Systole
• Ventricular depolarization causes contraction (QRS)
Relaxation Period
• Ventricular diastole – repolarization (T wave)
• Blood flows back into the atria
• Aortic and Pulmonic Valves close

69. ECG

70. CARDIAC VOLUME

71. Cardiac Output
Cardiac Output =
(Stoke Volume) x (Heart Rate)
Stroke Volume
• The volume of blood pumped from the left ventricle
of the heart with each contraction (approximately 15
mL)

72. Cardiac Output
Preload
• Also known as: End diastolic volume (EDV)
• Stroke volume is intrinsically controlled by preload (the
degree to which the ventricles are stretched prior to
contracting).
• An increase in the volume or speed of venous return will
increase preload
• Frank–Starling law of the heart
• Preload is equal to end diastolic volume
• Caused by:
• venous return
• Duration of ventricular diastole

73. Cardiac Output
Afterload
• Also know as Systemic Vascular Resistance
• The pressure the ventricle must exceed to eject blood
• Afterload is readily broken into components:
• Aortic pressure
• The pressure the ventricle must over come to eject
blood
• The greater the afterload the greater the ventricles must
work to eject blood (think of after load as increased blood
pressure in the system)