Download The Cardiovascular System: The Heart

The
Cardiovascular
System:
The Heart
CM
Cardiovascular System
• The major function of the
cardiovascular system is to
circulate substances
throughout the body.
• If cells do not circulate O2,
nutrients, and wastes, cells
will die
• Cardiology is the study of the
heart and the diseases
associated with it.
CM
A few questions.
CM
A few questions.
• Did you ask yourself, how did this guy die
of a heart attack.
A. Yes
B. No, I knew it was not a
heart attack.
C. I cannot remember what
I first thought but now I
know I was propofol.
CM
I’ll get to teaching you after I
throw a few more at you..
Which one is you:
A. I know all of these DJ; angina, cardiomegaly,
coronary artery disease, pericarditis, mitral
valve stenosis, fen-phen,
B. The only thing I know
is what I learned from
watching Sanford and
Son.
C. D.J., I need some
perspective here.
CM
Some perspective.
Heart disease is the leading
cause of death in the United
States and is a major cause
of disability. Almost 700,000
people die of heart disease
in the U.S. each year. That
is about 29% of all U.S.
deaths. Heart disease is a
term that includes several
more specific heart
conditions. The most
common heart disease in
the United States is
coronary heart disease,
which can lead to heart
attack.
CM
What are some of the
main pathologies?
•
•
•
•
•
•
•
•
•
Angina
Arrhythmia
Cardiac Arrest
Cardiomyopathy
Coronary Artery Disease
Endocarditis
Heart Attack
Heart Failure
Heart Valve Diseases
Medline Plus and Wiki are good
sources
Top Sources will be Professional
Societies or PubMed
CM
Let’s then concept map to see
the full dimension of our topic
and get a good perspective.
Let’s concept
map what we
need to know
of heart
function AND
the principles
that underlie
those
functions.
CM
Concept Map
If you would like to jump to a particular section, please click on it. If you want to return to the concept map, click the CM
CM
Basic Anatomy
CM
Heart Anatomy
• Approximately the size
of your fist
• It weighs about 300
grams
CM
A
B
Which is normal?
C
CM
A
B
Which will be
bigger than your
fist and will weigh
more than 300g?
C
CM
Which of the following would
you guess are not true?
A. Heart muscle, like any muscle, expands
when it has to work harder.
B. High blood pressure makes it hard for the
heart to pump.
C. High blood pressure pushes on the heart
muscle, making it
stronger in a “whatever
doesn’t hurt us us,
makes us grow stronger”
sort of way.
CM
A
B
Make you stronger?
Nonesense. What do
you expect to happen?
C
CM
A
B
Which will be
bigger than your
fist but will weigh
less than 300g?
C
CM
CPR
Heart Anatomy
• Location
– Superior surface of
diaphragm
– Left of the midline
– Anterior to the
vertebral column,
posterior to the
sternum
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Pericardial Layers
CM
Layers of the Heart: Two Major
Layers
• Two major layers are
considered:
– Pericardium
– Myocardium
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Pericardial Layers of the Heart
Function
1.Protects and
anchors
2.Prevents
overfilling
3.Creates
relatively
friction-free
environment
CM
Pericardial Layers
• Fibrous Pericaridum: outermost
covering
• Parietal Serous Pericardium:
outside wall of balloon
• Visceral Serous Pericardium:
inside wall of balloon
• Pericardial Cavity: air space
Fibrous Pericaridum
Parietal Serous Pericardium
Pericardial Cavity
Visceral Serous Pericardium
CM
Heart Wall
CM
Heart Wall
• Epicardium –
visceral layer of
the serous
pericardium
• Myocardium –
cardiac muscle layer
forming the bulk of
the heart
• Endocardium –
endothelial layer of
the inner myocardial
surface
CM
If you had to guess, what do you
think the endothelium is made of?
A.
B.
C.
D.
E.
Connective tissue
Muscle tissue
Adipose
Simple squamous epithelia
Mucosa
CM
Heart Wall
CM
If a knife penetrated the heart,
which is the correct sequence?
A. Endocardium, smooth muscle,
epicardium
B. Myocardium, pericardium, endocardium
C. Endocardium, epicardium, myocardium
D. Myocardium, Parietal pericardium,
endocardium
E. Epicardium, myocardium, endocardium
CM
Review Pericardial Layers
CM
Back to Basic Anatomy
CM
Gross Anatomy
• For the most part, you will need to be able to
label all figures like the one below.
CM
Gross Anatomy
• The heart consists of
four chambers
– Two atria and two
ventricles
• Major blood vessels of
the heart include
– Inferior and superior
vena cavae
– Aorta and pulmonary
trunk
CM
External Heart: Major Vessels of
the Heart (Anterior View)
• Vessels conveying blood
away from the heart
include:
– Pulmonary trunk, which
splits into right and left
pulmonary arteries
– Ascending aorta (three
branches) –
brachiocephalic, left
common carotid, and
subclavian arteries
CM
External Heart: Major Vessels of
the Heart (Anterior View)
• Vessels returning
blood to the heart
include:
– Superior and
inferior venae
cavae
– Right and left
pulmonary veins
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External Heart: Major Vessels of
the Heart (Posterior View)
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External Heart: Anterior View
CM
Gross Anatomy of Heart:
Frontal Section
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Gross Anatomy of Heart: Atria
1. Atria receive
2. Pectinate
muscles mark
atrial walls
3. Blood enters
right atria from
superior and
inferior venae
cavae and
coronary sinus
4. Blood enters left
atria from
pulmonary veins
CM
Gross Anatomy of Heart:
1. Ventricles are the
Frontal Section
discharging
chambers of the
heart
2. Papillary muscles
and trabeculae
carneae muscles
mark ventricular
walls
3. Right ventricle
pumps blood into
the pulmonary
trunk
4. Left ventricle
pumps blood into
the aorta
CM
• hyperheart
CM
Circulation
• Pulmonary
circuit
– blood to and
from the lungs
• Systemic circuit
– blood to and
from the rest of
the body
CM
The reason there are two
circulations is…
A. Oxygen loading is improved by slowing the circulation
through the pulmonary circuit, as opposed to the faster
circulation of the systemic circuit.
B. Pressures are lower in the pulmonary circuit to protect
the delicate lung tissue.
C. The circulation is too large to be served by only one
pathway.
D. All the above are correct.
CM
•Vessels
carry the
blood
through the
circuits
Circulation
Veins carry
blood to the
heart
Arteries
carry blood
away from
the heart
Capillaries permit
exchange
CM
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
right atrium
tricuspid valve
right ventricle
pulmonary
semilunar valve
pulmonary arteries
lungs
pulmonary veins
left atrium
bicuspid valve
left ventricle
aortic semilunar
valve
aorta
systemic circulation
Path of Blood
CM
CQ: Transposition of the Great Vessels
• Heather, a newborn baby, needs surgery because she was
born with an aorta that arises from the right ventricle and a
pulmonary trunk that issues from the left ventricle. What are
the physiological consequences of this defect?
A. While aberrant, there are no physiological consequence
because blood will continue to flow to the lungs to pick
up oxygen and to the body to nourish cells.
B. Oxygen-deficient blood will continually circulate in the
systemic circuit while oxygen rich blood will continually
circulate to the lungs.
C. Blood pressures to the brain will be abnormally high due
to the switch resulting in syncope (fainting) and possible
aneurysms.
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Coronary Arteries
CM
Coronary Circulation
• Coronary circulation is the functional blood
supply to the heart muscle itself
• Collateral routes ensure
blood delivery to heart
even if major vessels are
occluded
• Cabbage surgery
(CABG): Coronary Artery
Bypass Graft
CM
External Heart: Vessels of the Heart
(Anterior View)
• Arteries –
1. Right and left coronary (in atrioventricular
groove)
2. Marginal
3. Circumflex
4. Anterior interventricular arteries
•
Veins –
1. Small cardiac
2. Anterior cardiac
3. Great cardiac veins
CM
Coronary Arteries: Anterior View
CM
A patient reports pain in the lower right portion of
their heart (or more likely, low blood flow is
indicated by an ECG and visualization), what
artery is likely implicated?
A. Circumflex
B. Greater Artery
C. Marginal Artery
D. Anterior Interventricular
CM
Which of the following vessels is
most likely to supply the anterior
left ventricular myocardium?
A.
B.
C.
D.
E.
Marginal artery
Circumflex artery
Right coronary artery
Anterior interventricular artery
Posterior interventricular artery
CM
Coronary Veins: Anterior View
CM
External Heart: Vessels that
Supply/Drain the Heart
(Posterior View)
• Arteries –
1. Right coronary artery (in
atrioventricular groove)
2. Posterior interventricular artery (in
interventricular groove)
CM
Coronary Arteries: Posterior View
CM
External Heart: Vessels that
Supply/Drain the Heart
(Posterior View)
• Veins –
1.
2.
3.
4.
Great cardiac vein
Posterior vein to left ventricle
Coronary sinus
Middle cardiac vein
CM
Coronary Veins: Posterior View
CM
Which of the following factors
gives the myocardium its high
resistance to fatigue?
A. The presence of intercalated discs
B. A very large number of mitochondrion in the
cytoplasm
C. Gap junctions
D. The coronary circulation
CM
Which of the following factors
gives the myocardium its high
resistance to fatigue?
A. The presence of intercalated discs
B. A very large number of mitochondrion in the
cytoplasm
C. Gap junctions
D. The coronary circulation
CM
Review Coronary Arteries
CM
Heart Valves
CM
Heart Valves
•
•
Heart valves ensure unidirectional blood
flow through the heart
There are two main groups
1. Atrioventricular (AV): Between the atria and
ventricles
– Tricuspid (right)
– Bicuspid/Mitral (left)
2. Semilunar: Between the ventricles and
exiting blood vessels
– Pulmonary Semilunar
– Aortic Semilunar
CM
Heart Valves
•
•
Heart valves ensure
unidirectional blood flow
through the heart
There are two main
groups
1. Atrioventricular (AV):
Between the atria and
ventricles
– Tricuspid (right)
– Bicuspid/Mitral (left)
2. Semilunar: Between
the ventricles and
exiting blood vessels
– Pulmonary Semilunar
– Aortic Semilunar
CM
Heart Valves
CM
Atrioventricular Valve Function
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Semilunar Valve Function
CM
• hyperheart
CM
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
right atrium
tricuspid valve
right ventricle
pulmonary
semilunar valve
pulmonary arteries
lungs
pulmonary veins
left atrium
bicuspid valve
left ventricle
aortic semilunar
valve
aorta
systemic circulation
Path of Blood
CM
Put the valves in the correct order a rbc
would pass after returning from the systemic
circuit.
1. aortic semilunar valve
2. bicuspid (mitral) valve
3. pulmonary semilunar valve
4. tricuspid valve.
CM
Can you still do it?
1.
2.
3.
4.
5.
6.
7.
8.
Right atrium
Mitral valve
Aortic Semilunar valve
Pulmonary Semilunar Valve
Tricuspid valve
Left Ventricle
Right Ventricle
Left Atrium
CM
CM
Cardiac Cycle and Conduction System
(Basic Intro)
CM
The Cardiac Cycle
• The period between the start of one
heartbeat and the beginning of the next
• During a cardiac cycle
– Each heart chamber goes through
systole and diastole
• Systole = pumping or
contraction
• Diastole = rest
CM
The Cardiac Cycle
•
•
Correct pressure
relationships are
dependent on
careful timing of contractions
That careful timing arises from a
specific conduction system.
CM
Heart Physiology: Sequence of
Excitation
1. Sinoatrial (SA) node
generates impulses
about 75
times/minute
2. Atrioventricular (AV)
node delays the
impulse
approximately 0.1
second
3. Impulse passes from
atria to ventricles via
the atrioventricular
bundle (bundle of
His)
CM
Heart Physiology: Sequence of
Excitation
4. Bundle branches
carry the impulse
toward the apex of
the heart
5. Purkinje fibers carry
the impulse to the
heart apex and
ventricular walls
CM
Heart Physiology: Sequence of
Excitation
CM
Choose the correct sequence of
current flow through the heart wall.
A.
B.
C.
D.
E.
AV node, Purkinje fibers, AV bundle of His,
bundle branches
SA node, Purkinje fibers, AV node, AV bundle
of His, bundle branches
Purkinje fibers, AV node, AV bundle of His,
bundle branches, SA node
AV node, SA node, Purkinje fibers, AV bundle
of His, bundle branches
SA node, AV node, AV bundle of His, bundle
branches, Purkinje fibers
CM
Interactive Physiology
• If you are having trouble visualizing the
conduction cycle, please review Interactive
Physiology, the CD included with your
textbook.
http://www.interactivephysiology.com/ip10/
cardio/intrcond/topic4.html
CM
CM
Cardiac Cycle and Conduction System
(We’ll Be Back)
CM
Cardiac Cycle and Conduction System
(We’ll Be Back)
CM
• transition
CM
Cardiac Cycle and Conduction System
(The Electrical Basis)
CM
Microscopic Anatomy
of Heart Muscle
• Cardiac muscle is striated,
short, fat, branched, and
interconnected
• Intercalated discs anchor
cardiac cells together and
allow free passage of ions
• Heart muscle behaves as a
functional syncytium
– (i.e. there is a continuous electrical connection and
thus the muscle works together).
CM
Anatomy of Heart Muscle
CM
More Properties of Heart
Muscle
• It is stimulated by nerves and is
self-excitable (automaticity)
• Contracts as a unit
• It can only contract so often in a period of time.
– Technically stated, it has a long (250 ms) absolute
refractory period
• refractory periods are like a timeout, once the muscle has
been stimulated, it cannot respond again for 250 ms
• Cardiac muscle contraction is similar to skeletal
muscle contraction
CM
Heart Physiology:
Types of Cells
• There are two basic types of cells
in heart tissue.
– Autorhythmic cells: their job is
to just set the pace.
– Muscle cells: they respond to the
autorhythmic cells and contract.
• Their mechanisms are different
• I think it is worthwhile to understand specifically
how each type of cell works because we can
pharmacologically intervene in how they work.
– Beta blockers, nitroglycerine, etc. (or Google
“cardiac drugs”)
CM
Heart Physiology: Types of
Cells
• There are two basic
types of cells in heart
tissue.
– Autorhythmic cells:
their job is to just set
the pace.
– Muscle cells: they
respond to the
autorhythmic cells
and contract.
Sets the pace
Contracts the
muscle
CM
Heart Physiology:
Autorhytmic Cells
• Autorhythmic cells:
– Initiate action potentials
– Have unstable resting potentials called
pacemaker potentials
– Use calcium influx (rather than sodium) for
rising phase of the action potential
• Neurons use Na, heart cells use Ca
CM
Autorhythmic Action Potentials
of the Heart
CM
Cardiac Action Potentials
CM
Cardiac Action Potentials
The initial conditions are set up by the
Na+/K+ ATPase.
1. Ion gradient with Na+ on outside and K+ on
inside.
2. A charge gradient, with the inside of the cell
at -70mV.
CM
Cardiac Action Potentials
• Voltage-gated channels, sense the
voltage and can open and close.
CM
Cardiac Action Potentials
• Different voltage-gated ion channels exist
to let through different ions at different
voltages.
CM
Na+ Channels
• Na + channels usually
open at around -55mV.
• Na + follows its
concentration gradient
and enters.
• Since Na+ is positive, it
makes Vm move
toward positive
voltages.
CM
Ca++ Channels
• There are two types of Ca++
channels that allow calcium to
enter and depolarize cells.
– Fast:
• Open at -40 mV and stay
open for a short time.
• In AR cells and help set the
pace.
– Slow:
• Open at 0 mV and maintain the
plateau in muscle cells.
CM
K+ Channels
• K+ channels usually
open at around 0 mV.
• K+ follows its
concentration gradient
and leaves the cell.
• Since a + ion is leaving
the cell, Vm moves
negative.
CM
Cardiac Action Potentials
CM
Putting it all
together for
AR Cells
CM
Which of the following ions has a
affect on the autorhythmic capabilities
of the myocardium?
A.
B.
C.
D.
ClCa2+
Na+
I
CM
+
Increasing Na concentration
will…
A. Cause more Na+ to leak into
the AR cell, thus decreasing
heart rate.
B. Cause more Na+ to leak into
the AR cell, thus increasing
heart rate.
C. Have an insignificant effect on
HR.
CM
Heart Physiology: Muscle Cells
• Muscle action potentials differ from
autorhythmic cell action potentials.
• First, there is no slow leak of Na.
• Second, Ca and K channels are open
together to cause a sustained contraction.
• K channels still end the action potential.
CM
Putting it all
together for
Muscle Cells
CM
Muscle Action Potentials
K+
Ca++
Time (msec)
©
Ion Permeability
Membrane Potential
(mvolts)
Na+
W. Diehl-Jones
CM
Cardiovascular
System
TOPIC: Cardiac Action Potential
PAGE 11 OF 19
Contractile Cell Anatomy
CM
The depolarization phase of the
cardiac muscle action potential
occurs when
A. Voltage-gated Ca2+ ion
channels open.
B. Voltage-gated K+ ion channels
open.
C. Voltage-gated Na+ ion channels
open.
D. Both b and c
CM
Which of these conditions occur in
the cardiac muscle cell during the
plateau phase?
A) Voltage-gated Ca2+ ion channels are open
B) Voltage-gated K+ ion channels are open
C) Voltage-gated Na+ ion channels are closed
D) All of these
CM
In cardiac cells, Ca2+ is responsible
for _________ while in muscle cells it
is necessary to initiate __________?
A) Depolarization, muscle contraction
B) Muscle contraction, depolarization
C) Releasing neurotransmitter
D) Causing the release of calcitonin
CM
Thus, if we could control either calcium
concentrations or the flow of calcium
through ion channels, we could alter how
fast the heart beats (chronotropic effects), or
how hard the heart beats (ionotropic
effects).
A. True
B. False
CM
Blocking Ca2+ channels in
AR cells would ____.
A. Speed up the heart rate (positive chronotrophy)
B. Slow down the heart rate (negative chronotrophy)
C. Cause increased strength of contraction (positive
ionotrophy)
D. Cause decreased strength of contraction (negative
ionotrophy)
CM
Blocking Ca2+ channels in
heart muscle cells
would….
A. Speed up the heart rate (positive chronotrophy)
B. Slow down the heart rate (negative chronotrophy)
C. Cause increased strength of contraction (positive
ionotrophy)
D. Cause decreased strength of contraction (negative
ionotrophy)
CM
If the body wanted to speed up both
HR and increase contractility, it
could…
A.
B.
C.
D.
Inhibit Na+ channels
Stimulate K+ channels
Inhibit K+ channels
Stimulate Na+ channels
CM
A chemical in the body that does
speed up both HR and increases
contractility, is…
A.
B.
C.
D.
Serotonin
Adrenaline
Thyroxin
Growth Hormone
CM
Because we can inhibit this
substance, we can pharmacologically
slow HR and relax contractility with…
A.
B.
C.
D.
E.
Aspirin
Beta Blockers
Nitroglycerin
SSRIs
Diuretics
CM
So Beta blockers must…
A.
B.
C.
D.
Inhibit Na+ channels
Stimulate K+ channels
Inhibit K+ channels
Stimulate Na+ channels
CM
Cardiac Cycle and Conduction System
(The Electrical Basis) Review
CM
• transition
CM
Cardiac Cycle and Conduction System
The ECG
CM
Electrocardiography
• Electrical activity is recorded by
electrocardiogram (ECG)
• P wave corresponds to depolarization of SA
node
• QRS complex corresponds to ventricular
depolarization
• T wave corresponds to ventricular repolarization
• Atrial repolarization record is masked by the
larger QRS complex
CM
Heart Excitation Related to ECG
CM
ECG
CM
ECG: How Should I Teach It?
• There is a really simple description that hints at
what is occurring, but it doesn’t really help you to
actually read an ECG.
• I can give you enough that you pick out major
problems in ECG and you can also extend on it
if you are planning on working on a cardiac unit.
• I will give both descriptions, the first as an
introduction and the second because you should
at least be able to pick out major issues.
CM
Simple Description: Two “rules”
of ECGs
1. Currents down the heart are seen as
upward deflections.
• And, currents up the heart are seen as
downward deflections.
2. All currents create an up and a
downward deflection
• Because all currents cause a
depolarization and a repolarization.
CM
Simple Description: Two “rules”
of ECGs
1. Currents down the
heart are seen as
upward deflections.
• And, currents up the
heart are seen as
downward deflections.
CM
Simple Description: Two “rules”
of ECGs
2. All currents create an
upward and a
downward deflection
• Because all currents
cause a depolarization
and a repolarization.
ECGs see voltage
changes and there
are two large
voltage changes
CM
ECG:
Simple
Description
CM
ECG:
Simple
Description
CM
ECG:
Simple
Description
CM
ECG:
Simple
Description
CM
ECG:
Simple
Description
CM
ECG:
Simple
Description
P-Q: time
between atrial
systole and
ventricular systole
T-P interval: heart
rate
CM
Simple Description: Atrial
Fibrillation
CM
Simple Description: WolfParkinson-White
CM
Simple Description: Ventricular
Defibrillation
CM
During the QT interval of the
EKG, the
A. Atria contract and begin to relax.
B. Atria relax.
C. Ventricles contract and begin to
relax.
D. Ventricles relax.
CM
An enlarged R wave on an ECG
would indicate
A.
B.
C.
D.
An enlarged ventricle.
Repolarization abnormalities.
A myocardial infarction.
Cardiac ischemia.
CM
Which interval is more likely to
change often?
A. P-Q
B. QRS-T
C. T-P
D. Q-S
CM
More Complex Description: What will you really
see? 12-Lead ECG
CM
If you would like some
introduction with animation,
please try this site.
• http://www.blaufuss.org/SVT/index.html#
CM
Four Limbs Plus Precordials
CM
Three pieces of the puzzle.
1. What are the voltage
changes that occur in the
cardiac conduction cycle?
2. What are the leads used to
pick up the voltage
channels?
3. How do the leads
specifically report the
voltage changes?
CM
1. What are the voltage changes that occur
in the cardiac conduction cycle?
• First, we have to get a little more technical
about the conduction cycle. At left is that
“electrical engineering” version of the cycle.
CM
The Cardiac Conduction Cycle
• Next, we have to remember that the
conduction cycle is made up of voltage
changes.
ECGs see voltage
changes and there
are two large
voltage changes
CM
2. What are the leads used to
pick up the voltage channels?
• These voltage changes are picked up by
“leads.”
• The main
leads we will
focus on are I,
II, and III.
• We will also
interpret aVR,
aVL, and aVF
CM
The Leads are Described by
Einthoven’s Triangle
• There are
also the
precordial
leads which
measure
voltages in
transverse
section.
CM
3. How do the leads specifically
report the voltage changes?
• Lastly, we know voltage changes, we know the leads,
how do the leads report the voltage changes.
– The lead will report a voltage change only if it is
parallel to the lead.
– If the voltage change is in the same direction of the
lead, it will be positive on the trace. If the voltage
change is in the opposite direction of the lead, it will
be negative on the trace.
At left is how the
voltage changes,
represented by
blue arrows,
would be “seen”
by Lead II
CM
One last piece of the puzzle.
A larger view of how the
voltage changes, represented
by blue arrows, would be
“seen” by Lead II
CM
One step in the excitation
sequence at a time.
Lets then put all these together:
1. The voltage changes of the excitation
sequence.
2. If the voltage is parallel to the lead.
3. If the voltage is with the lead (+) or against
the lead (-).
CM
12 Lead ECG:Depolarization of
the atria
Activation begins in
the SA-node
0 ms
CM
12 Lead ECG: Repolarization of
Atria
Atrial
depolarization
80 ms
CM
12 Lead ECG: Septal
Depolarization
Atria depolarized
200 ms
CM
12 Lead ECG: Apical
Depolarization
Septal depolarization
220 ms
CM
12 Lead ECG: Late Left Ventricular
Depolarization
Left ventricular
depolarization
240 ms
CM
12 Lead ECG: Repolarization of
Ventricles
Late left ventricular
depolarization
250 ms
CM
More in Lab
• We will follow up in lab
and…
– Get you your own ECG
strip.
– Check your strip for
normal.
– Discuss further
interpretation of…
• Intervals
• Segments.
• QRS axis
• QRS-T angle
• P axis
• Conduction path
• Etc.
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Cardiac Cycle and Conduction System
The ECG (Review)
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CM
Cardiac Cycle and Conduction System
Heart Sounds
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Heart Sounds
• Heart sounds (lub-dup) are associated
with closing of heart valves
– First sound occurs as AV valves close and
signifies beginning of systole
– Second sound occurs when SL valves close
at the beginning of ventricular diastole
– May be the opposite of what you think
intuitively
http://www.blaufuss.org/SVT/index.html
http://members.aol.com/kjbleu/heartsounds.html
CM
Heart Sounds
• Heart sounds (lub-dup)
are associated with
closing of heart valves
– First sound occurs as
AV valves close and
signifies beginning of
systole
– Second sound occurs
when SL valves close at
the beginning of
ventricular diastole
– May be the opposite of
what you think intuitively
Lub Sound: A/V Valves
Dub Sound: S/L Valves
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Heart Sounds
• Auscultation – listening to heart sound via
stethoscope
• Four heart sounds
– S1 – “lubb” caused by the closing of the AV valves
– S2 – “dupp” caused by the closing of the semilunar
valves
– S3 – a faint sound associated with blood flowing into
the ventricles
– S4 – another faint sound associated with atrial
contraction
CM
Heart Sounds
CM
The second heart sound, described as
"dupp" is actually the sound of the
A) Atria contracting.
B) Ventricles contracting.
C) Atrioventricular valves closing.
D) Semilunar valves closing.
E) Heart slapping the liver.
CM
CM
Cardiac Cycle and Conduction System
The Wigger Diagram (Review)
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The Wigger
Diagram
• You will
know it all
before we
are done.
• This is one
of the most
beautiful
figures in all
of A&P.
• We’ll start
down here.
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The Cardiac Cycle
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Cardiac Cycle
• The cardiac cycle refers to all events
associated with blood flow through the
heart
– Systole – contraction of heart muscle
– Diastole – relaxation of heart muscle
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Phases of the Cardiac Cycle
• Ventricular filling – mid-to-late diastole
– Heart blood pressure is low as blood enters atria
and flows into ventricles
– AV valves are open, then atrial systole occurs
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Phases of the Cardiac Cycle
• Ventricular Filling/Atrial Contraction
– AV valves are open, then atrial systole occurs
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Phases of the Cardiac Cycle
• Ventricular systole/Isovolumetric contraction
– Atria relax
– Rising ventricular pressure results in closing of
AV valves
– Isovolumetric (same volume) contraction phase
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Phases of the Cardiac Cycle
• Ventricular systole/Ventricular ejection
– The contraction of the ventricle builds pressure
– The pressure forces open the semilunar valves.
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Phases of the Cardiac Cycle
• Early Diastole/Isovolumetric relaxation
– Ventricles relax
– Valves remain closed so there is no change in the
volume of blood in the ventricle (isovolumetric).
– Backflow of blood in aorta and pulmonary trunk closes
semilunar valves
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Phases of the Cardiac Cycle
• Isovolumetric relaxation – early diastole
– Ventricles relax
– Backflow of blood in aorta and pulmonary trunk closes
semilunar valves
• Dicrotic notch – brief rise in aortic pressure caused
by backflow of blood rebounding off semilunar
valves
CM
Phases of the Cardiac Cycle
• Start all over
• Ventricular filling – mid-to-late diastole
– Heart blood pressure is low as blood enters atria and
flows into ventricles
– AV valves are open, then atrial systole occurs
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Phases of
the Cardiac
Cycle
CM
The phase in the cardiac cycle in which the
ventricles are completely closed and the
volume of blood in them is constant is
referred to as the
A.
B.
C.
D.
Ventricular ejection phase.
Quiescent period.
Isovolumetric relaxation phase.
Isovolumetric contraction phase.
CM
The end diastolic volume is the
A. Volume of blood in the atria at the end of atrial
contraction.
B. Volume of blood in the atria at the end of atrial
relaxation.
C. Volume of blood in the ventricle at the end of
ventricular contraction.
D. Volume of blood in the ventricle at the end of
ventricular relaxation.
CM
The average end-diastolic volume of the
ventricles is about __________ , whereas the
end-systolic volume is about __________ .
A.
B.
C.
D.
E.
130 mL, 70 mL
130 mL, 0 mL
0 mL, 70 mL
0 mL, 130 mL
70 mL, 130 mL
CM
At the end of __________ , the
ventricles are 90% filled.
A) Active ventricular filling
B) Passive ventricular filling
C) Ventricular diastole
D) Atrial systole
E) Atrial diastole
CM
At the end of __________ , the
ventricles are 55% filled.
A) Active ventricular filling
B) Passive ventricular filling
C) Ventricular diastole
D) Ventricular systole
E) Atrial systole
CM
During the period of ejection, the left
ventricular pressure reaches an
average pressure of approximately
– A) 20 mm Hg.
– B) 60 mm Hg.
– C) 80 mm Hg.
– D) 100 mm Hg.
– E) 120 mm Hg.
CM
More Wiggers Questions?
• There is an additional PPT entitled
Wiggers Diagram Questions on Angel to
test your skills.
Cardiac Cycle and Conduction System
The Wigger Diagram (Review)
CM
• transition
CM
Cardiac Cycle and Conduction System
Cardiac Output
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Quantification of Heart
Function
• Heart Rate
– How fast the heart is pumping
• Stroke Volume
– How much the heart is pumping
• Cardiac Output
– Overall combination of how fast
the heart is pumping and how
much the heart is pumping
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Cardiac Output (CO)
• CO is the amount of blood pumped by
each ventricle in one minute
• CO is the product of
heart rate (HR) and
stroke volume (SV)
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Cardiac Output: Example
• CO (ml/min) = HR (75 beats/min) x SV (70
ml/beat)
• CO = 5250 ml/min (5.25 L/min)
CO
Cardiac
output
(ml/min)
=
HR
Heart rate
(beats/min)
X
SV
Stroke
volume
(ml/beat)
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Heart Rate
• Number of Heart Beats per time
• 75 beats per minute
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Regulation of Stroke Volume
• SV = end diastolic volume (EDV) minus
end systolic volume (ESV)
• EDV = amount of blood collected in a
ventricle during diastole
• ESV = amount of blood remaining in a
ventricle after contraction
• Basically, how much blood (in mL) was
pumped.
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Stroke
Volume
• SV = end diastolic
volume (EDV) minus
end systolic volume
(ESV)
• EDV = amount of
blood collected in a
ventricle during
diastole
• ESV = amount of
blood remaining in a
ventricle after
contraction
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Factors Affecting Cardiac
Production
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Factors Affecting Cardiac
Production
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Factors Affecting Stroke Volume
• Preload – amount ventricles are stretched
by contained blood
• Contractility – cardiac cell contractile force
due to factors other than EDV
• Afterload – back pressure exerted by
blood in the large arteries leaving the heart
CM
Frank-Starling Law of the Heart:
Preload
• Preload, or degree of stretch, of cardiac muscle
cells before they contract is the critical factor
controlling stroke volume
– The heart has the intrinsic capability of increasing its
force of contraction and therefore stroke volume in
response to an increase in venous return.
• An elegant property of cardiac muscle, if it is prestretched, it
contracts harder.
• Slow heartbeat and exercise increase venous
return to the heart, increasing SV
• Blood loss and extremely rapid heartbeat decrease
SV
CM
If you want the details of Starling
• http://www.cvphysiology.com
• The mechanical basis for this mechanism is
found in the length-tension and force-velocity
relationships for cardiac myocytes. Briefly,
increasing the sarcomere length increases
troponin C calcium sensitivity, which increases
the rate of cross-bridge attachment and
detachment, and the amount of tension
developed by the muscle fiber (see ExcitationContraction Coupling). The effect of increased
sarcomere length on the contractile proteins is
termed length-dependent activation.
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Extrinsic Factors Influencing
Stroke Volume
• Contractility is the increase in contractile strength,
independent of stretch and EDV
• Only cardiac muscle can vary contractile strength
– Contract weakly
– Contract strongly
• http://cvphysiology.com/Cardia
c%20Function/CF010.htm
CM
Extrinsic Factors Influencing
Stroke Volume
• Increase in contractility
comes from:
– Increased sympathetic
stimuli (big dog)
– Certain hormones
– Ca2+ and some drugs
• Agents/factors that
decrease contractility
include:
– Acidosis
– Increased extracellular K+
– Calcium channel blockers
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Afterload
• When you lift something
heavy, you do it slow.
When you have back
pressure, your heart must
pump slow.
• You have a finite time to
pump, so if you pump
slow, you decrease your
stroke volume.
CM
Regulation of Heart Rate:
Autonomic Nervous System
• Sympathetic nervous system (SNS)
stimulation is activated by stress, anxiety,
excitement, or exercise
• Parasympathetic nervous system (PNS),
stimulation is mediated by acetylcholine
and opposes the SNS (also called Vagal)
• PNS dominates the autonomic stimulation,
slowing heart rate and causing vagal tone
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Opposing Systems
Parasympathetic
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Atrial (Bainbridge) Reflex
• Atrial (Bainbridge) reflex – a sympathetic
reflex initiated by increased blood in the
atria
– Causes stimulation of the SA node
CM
Regulation of Cardiac Output
CM
Increased venous return to the
heart causes increased
A.
B.
C.
D.
E.
Stroke volume.
Preload.
Cardiac output.
Force of contraction.
All of these
CM
If the left ventricle begins to pump a
higher volume then the right side…
A. Beats faster than the left.
B. This never happens.
C. Will increase contractility via an increase in
preload to balance the volumes.
CM
While preload can be beneficial in
hemorrhage, its affect on decreases in
BP due to edema is…
A. Still beneficial
B. Could result in a positive feedback
that results in lower and lower BP.
C. Will have little effect because it will
be offset by other cardiac controls.
CM
Cardiac Cycle and Conduction System
Cardiac Output (Review)
CM
Congestive Heart Failure
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Congestive Heart Failure (CHF)
•
Congestive heart failure (CHF) is caused
by:
1.
2.
3.
4.
Coronary atherosclerosis
Persistent high blood pressure
Multiple myocardial infarcts
Dilated cardiomyopathy (DCM)
CM
Congestive Heart Failure (CHF)
•
•
A downward cycle of heart function:
The heart
–
–
–
–
–
•
Cannot pump enough blood
Less blood makes it back to be pumped
Heart muscle is malnourished
Malnourishment damages heart muscle
Cannot pump enough blood
The kidneys
– Inadequate heart function results in inability to force fluid
through kidney, and edema results.
•
The lungs:
– Lungs fill with fluid due to edema, less oxygen loading,
fewer nutrients, heart muscle is malnourished.
CM
CHF Drags Other Systems In
http://www.youtube.com/watch?v=b2q672l
G3Nk
Click to go there
CM
Congestive
Heart Failure
(CHF)
CM
CS
• This 67-year-old female was transferred to
the hospital from a nursing home in a
comatose state. Physical findings on
examination were compatible with brain
stem infarction. On the fourth hospital day,
an electrocardiogram revealed changes
compatible with anterior myocardial
infarction. The patient remained comatose
with quadriplegia and expired on the 16th
hospital day.
CM
CS: Which of the following are possible
connections between the brain stem
infarction and the cardiac infarction?
A. They could be separate events.
B. The infarct in the heart caused decreased
blood flow resulting in infarction of the
brain stem.
C. Blood clots formed at the site of the
coronary infarction, which traveled to the
brain stem.
CM
All three could be correct.
• This is a frontal section of the right atrium
at autopsy revealing a large thrombus that
could release clots. When the clots travel,
they cause blockages elsewhere.
CM
Why would the clot form?
• Platelets bind to damage endocardium
• This results in recruitment of more
platelets and activation of the clotting
cascade.
• Thrombin is activated leading to fibrin
polymerization.
• This process results in the development of
a platelet-fibrin thrombus.
CM
Collagen leaks out of damaged
tissue. What else leaks out of
damaged muscle cells?
A. Hemoglobin
B. Creatinin
C. Troponin
D. Myoglobin
Click
CM
Men vs. Women: Heart Attach
Symptoms
Women’s Symptoms
Angina (chest pain may radiate into jaw and
down left shoulder and arm)
Men’s Symptoms
1. Sudden immense pressure or
pain in the chest center (may
persist or occur on and off)
Breathlessness (especially at night)
Chronic fatigue (usually overwhelming)
2. Pain that radiates from chest
center to neck, shoulders, and
arms
Dizziness or even blackouts
3.
Dizziness, nausea, sweating
Edema or swelling, especially in the ankles
Fluttering (rapid heartbeat) and pallor
4. Sudden onset of rapid
heartbeat
Gastric upset (nausea) and sweating
CM
Examples of Congenital Heart
Defects
CM