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CHAPTER 15: THE
CARDIOVASCULAR SYSTEM
HEART PHYSIOLOGY
BIO 139
ANATOMY AND PHYSIOLOGY II
MARY CATHERINE FLATH, Ph.D.
THE CARDIOVASCULAR
SYTEM


ORGANS
 HEART
 BLOOD VESSELS
FUNCTION
 TRANSPORT OF BLOOD
CARRY OXYGEN AND NUTRIENTS TO CELLS
 CARRY CARBON DIOXIDE AND WASTES
AWAY FROM CELLS

Copyright 2016 Dr. Mary Cat Flath
Copyright 2016 Dr. Mary Cat Flath
Copyright 2016 Dr. Mary Cat Flath
PULMONARY CIRCULATION
RIGHT ATRIUM
TRICUSPID VALVE
RIGHT VENTRICLE
PULMONARY SEMILUNAR VALVE
PULMONARY TRUNK
PULMONARY ARTERY
LUNG CAPILLARIES
PULMONARY VEINS
LEFT ATRIUM
BICUSPID/MITRAL VALVE
LEFT VENTRICLE
AORTIC SEMILUNAR VALVE
AORTA
Copyright 2016 Dr. Mary Cat Flath
Copyright 2016 Dr. Mary Cat Flath
RIGHT
ATRIUM
TRICUSPID VALVE
RIGHT
VENTRICLE
LEFT
ATRIUM
BICUSPID VALVE
LEFT
VENTRICLE
Copyright 2016 Dr. Mary Cat Flath
Lung
Capillaries
Summary of Circulation
CORONARY
17. Coronary
Sinus
PULMONARY
1. Right Atrium
2. Tricuspid Valve
3. Right Ventricle
16.Cardiac
Veins
SYSTEMIC
23. Vena
Cavae
22. Veins
4. Pulmonary Semilunar Valve
5. Pulmonary Trunk
21. Venules
6. Pulmonary Arteries
15.Myocardial
Capillaries
7. Lung Capillaries
8. Pulmonary Veins
20. Tissue
Capillaries
9. Left Atrium
10. Bicuspid (Mitral Valve)
14. Coronary
Arteries
19. Arterioles
11. Left Ventricle
12. Aortic Semilunar Valve
13. Aorta
Copyright 2016 Dr. Mary Cat Flath
18. Arteries
CARDIAC PHYSIOLOGY
Heart Physiology
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Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
 Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Cardiac Conduction System
1. SINOATRIAL
2. ATRIOVENTRICULAR
4B.
3. ATRIOVENTRICULAR
4A.
5.
Copyright 2016 Dr. Mary Cat Flath
15-22
Cardiac Conduction System
Copyright 2016 Dr. Mary Cat Flath
15-21
Heart Physiology

Cardiac Conduction System
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Sino-atrial Node
Atrioventricular Node
Atrioventricular Bundle
Right and Left Bundle Branches
Purkinje Fibers
Ion Channel Involvement and Electrical Event
 Electrical Event resulting in Mechanical Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac
Cycle
Copyright 2016 Dr. Mary Cat Flath
Heart Physiology





Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
 Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Physiology of Cardiac Muscle
Contraction


Resting Membrane potential in Cardiac
Muscle cells is -90mV (inside/outside)
RMP is established by distribution of ions
across sarcolemma
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High potassium inside cell
High sodium, chloride, calcium outside cell
High negatively charged proteins inside cell
RMP is maintained by the Na+-K+-ATPase
pump
Copyright 2016 Dr. Mary Cat Flath
Resting Membrane Potential in
Cardiac Muscle cells is -90mV (inside/outside)
Copyright 2016 Dr. Mary Cat Flath
Physiology of Cardiac Muscle
Contraction: Electrical Event precedes
Mechanical Event


DEPOLARIZATION PRECEDES
CONTRACTION
 DEPOLARIZATION IS DUE TO OPENING
OF SODIUM CHANNELS
 CONTRACTION IS DUE TO SUSTAINED
OPENING OF CALCIUM CHANNELS
REPOLARIZATION PRECEDES RELAXATION
 REPOLARIZATION IS DUE TO OPENING
OF POTASSIUM CHANNELS
Copyright 2016 Dr. Mary Cat Flath
Physiology of Cardiac Muscle
Contraction

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RMP of -90mV is depolarized (to -70mV)
Sodium channels open and Na+ rushes into
muscle fiber producing rapid depolarization
Calcium channels open and Ca++ rushes in
causing contraction mechanism to begin


Calcium channel blockers decrease strength of
heartbeat
Potassium channels open, K+ flows out reestablishing the RMP to -90mV.

Refractory period
Copyright 2016 Dr. Mary Cat Flath
ION CHANNEL INVOLVEMENT IN CARDIAC MUSCLE CONTRACTION
Copyright 2016 Dr. Mary Cat Flath
Heart Physiology


Cardiac Conduction System
Ion Channel Involvement and Electrical Event
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

Electrical Event resulting in Mechanical Event
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Opening of Sodium Channels = depolarization
Opening of Calcium Channels = contraction
Opening of Potassium Channels = repolarization
Depolarization precedes contraction
Repolarization precedes relaxation
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Heart Physiology






Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Electrocardiogram
• recording of
electrical changes that occur in the
myocardium
• used to assess heart’s ability to conduct impulses
• can detect enlarged regions of heart
• can detect damaged areas
P wave – atrial depolarization
QRS wave – ventricular depolarization
T wave – ventricular repolarization
Copyright 2016 Dr. Mary Cat Flath
15-24
Copyright 2016 Dr. Mary Cat Flath
The ECG

P wave
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QRS wave
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Small upward wave
Atrial depolarization
Followed by atrial contraction
Begins a downward deflection, comes up sharply, and then
downward again
Ventricular depolarization
Follows by ventricular contraction
T wave
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Slow, dome-shaped upward deflection
Ventricular repolarization
Followed by ventricular relaxation
Copyright 2016 Dr. Mary Cat Flath
= ventricular
depolarization
SA Node Fires
l
= ventricular
repolarization
=atrial
depolarization
^atrial
contraction
^ventricular
contraction
Copyright 2016 Dr. Mary Cat Flath
^ventricular
relaxation
Normal ECG:
Sinus Rhythm
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21b
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21c
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21d
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21e
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21f
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21g
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21h
Copyright 2016 Dr. Mary Cat Flath
Figure 15.21
Copyright 2016 Dr. Mary Cat Flath
Normal ECG:
Sinus Rhythm
Copyright 2016 Dr. Mary Cat Flath
Abnormal ECGs: Arrythmias or
Dysrythmias
A prolonged QRS complex may result from damage to the A-V
bundle fibers
Copyright 2016 Dr. Mary Cat Flath
15-26
ABNORMAL ECGs
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ENLARGED P WAVE
 ATRIAL HYPERTROPHY DUE TO
MITRAL STENOSIS
ENLARGED Q WAVE
 MI
ENLARGED R WAVE
 VENTRICULAR HYPERTROPHY
Copyright 2016 Dr. Mary Cat Flath
Clinical Application
Arrhythmias- Dysrythmias
Ventricular fibrillation **********
• rapid, uncoordinated depolarization
of ventricles
Tachycardia
• rapid heartbeat
Atrial flutter
• rapid rate of atrial depolarization
Copyright 2016 Dr. Mary Cat Flath
15-71
Heart Physiology


Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
 Electrical Event resulting in Mechanical
Event

ECG (measurement of electrical event)
 P = atrial depolarization
 QRS = ventricular depolarization
 T = ventricular repolarization

Events of the Cardiac Cycle
Regulation of Cardiac Cycle

Copyright 2016 Dr. Mary Cat Flath
Heart Physiology






Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Heart Actions: Dual Pump
Atrial Systole/Ventricular Diastole
Atrial Diastole/Ventricular Systole
Copyright 2016 Dr. Mary Cat Flath
15-16
Phase
Bloodflow
Valves
Pressure
Ventricular
Systole
Atrial
Diastole
Ventricular
Diastole
Atrial
Systole
Phase
Ventricular
Systole
Atrial
Diastole
Bloodflow
From
From
ventricles
veins into
into arteries atria
Valves
SL open
AV closed
SL open
AV closed
Pressure
Ventricular
p high
Atrial p
low, but
increases
Ventricular
Diastole
Atrial
Systole
Phase
Ventricular
Systole
Atrial
Diastole
Ventricular
Diastole
Atrial
Systole
Bloodflow
From
From
From atria
ventricles
veins into into
into arteries atria
ventricles
Valves
SL open;
AV closed
SL open; AV open; SL AV open;
SL closed
AV closed closed
Pressure
Ventricular
p high
Atrial p
Ventricular
low, but p low, but
increases increases
From atria
into
ventricles
Atrial p
high
Cardiac Cycle
Atrial Systole/Ventricular Diastole
• blood flows passively into ventricles
• remaining 30% of blood pushed into ventricles
• A-V valves open/semilunar valves close
• ventricles relaxed
• ventricular pressure increases
Ventricular Systole/Atrial diastole
• A-V valves close
• chordae tendinae prevent cusps of valves from bulging too far
into atria
• atria relaxed
• blood flows into atria
• ventricular pressure increases and opens semilunar valves
• blood flows into pulmonary trunk and aorta
15-17
Copyright 2016 Dr. Mary Cat Flath
Specific Phases of the Cardiac
Cycle

Relaxation (Quiescent) Period (Early ventricular
diastole)
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Follows T-wave
Ventricular pressure drops
SL valves close
Isovolumetric relaxation phase for brief time
When ventricular pressure drops below atrial pressure, AV
valves open
0.4 seconds
Ventricular Filling
Ventricular Systole
Copyright 2016 Dr. Mary Cat Flath
Specific Phases of the Cardiac
Cycle


Relaxation (Quiescent) Period
Ventricular Filling (Mid to Late Ventricular
Diastole)
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Rapid ventricular filling occurs just after AV valves
open
SA Node fires (P wave)
Atria contract and remainder of ventricular filling
occurs
Atria relax as ventricles are deplolarized (QRS)
0.1 second
Ventricular Systole
Copyright 2016 Dr. Mary Cat Flath
Specific Phases of the Cardiac
Cycle
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Relaxation (Quiescent) Period
Ventricular Filling
Ventricular Systole
 Impulse passes through AV Node, bundle
branches, and Purkinje fibers of ventricles
 Ventricles contract and ventricular pressure rises
quickly
 AV Valves close
 Isovolumetric contraction phase (0.05seconds)
Copyright 2016 Dr. Mary Cat Flath
 0.3 seconds
Phase
Bloodflow
Valves
Pressure
Ventricular
Systole
Atrial
Diastole
Ventricular
Diastole
Atrial
Systole
Phase
Ventricular
Systole
Atrial
Diastole
Ventricular
Diastole
Atrial
Systole
Bloodflow
From
From
From atria
ventricles
veins into into
into arteries atria
ventricles
Valves
SL open;
AV closed
SL open; AV open; SL AV open;
SL closed
AV closed closed
Pressure
Ventricular
p high
Atrial p
Ventricular
low, but p low, but
increases increases
From atria
into
ventricles
Atrial p
high
Heart Sounds
Lubb
• first heart sound
• occurs during ventricular contraction (systole)
• A-V valves closing
Dupp
• second heart sound
• occurs during ventricular relaxation (diastole)
• semilunar valves closing
Murmur – incomplete closing of valve cusps;
abnormal heart sound
Copyright 2016 Dr. Mary Cat Flath
15-18
Heart Sounds
Copyright 2016 Dr. Mary Cat Flath
15-19
Heart Physiology




Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
 Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle: Dual Pump

Systole vs. Diastole
 Chamber pressure
 Blood Flow
 Valve Action Copyright 2016 Dr. Mary Cat Flath
Heart Physiology Summary






Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
Copyright 2016 Dr. Mary Cat Flath
Copyright 2016 Dr. Mary Cat Flath
Heart Physiology Summary






Cardiac Conduction System
Ion Channel Involvement and Electrical
Event
Electrical Event resulting in Mechanical
Event
ECG (measurement of electrical event)
Events of the Cardiac Cycle
Regulation of Cardiac Cycle
Copyright 2016 Dr. Mary Cat Flath
CARDIAC OUTPUT (CO)
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CO is the volume of blood pumped by
each ventricle in a minute
CO = heart rate (HR) multiplied by
stroke volume (SV)
SV = the volume of blood pumped by
each ventricle with each beat
Normal CO is approximately 5 liters
Copyright 2016 Dr. Mary Cat Flath
Regulation of Cardiac Cycle
•cardiac center regulates autonomic impulses to the heart
▪ parasympathetic impulses decrease heart action
▪ sympathetic impulses increase heart action
▪ concentration of various ions
▪ potassium and sodium decrease heart action
▪ calcium increases heart action
• physical exercise increases heart action
• increase in body temperature increases heart action
• age deceases heart action
• sex influences heart action
• Females increased
• Males decreased
Copyright 2016 Dr. Mary Cat Flath
15-28
Regulation of Cardiac Cycle
Autonomic nerve impulses alter the activities of S-A & A-V nodes
Copyright 2016 Dr. Mary Cat Flath
15-29
Regulation of Cardiac Cycle will be
discussed in greater detail later re:
blood pressure
Let’s review objectives
19-30.