The Pulmonary Circuit Carries blood to and from gas exchange surfaces of lungs The Systemic Circuit Carries blood to and from the body Blood alternates between pulmonary circuit and systemic circuit ID: 774840
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Slide1
Slide2An Introduction to the Cardiovascular System
The
Pulmonary
Circuit
Carries blood to and from gas exchange surfaces of lungs
The
Systemic
Circuit
Carries blood to and from the body
Blood alternates between pulmonary circuit and systemic circuit
Slide3An Introduction to the Cardiovascular System
Three Types of Blood Vessels
Arteries
Carry blood
away
from heart
Veins
Carry blood
to
heart
Capillaries
Networks
between
arteries and veins
Slide4An Introduction to the Cardiovascular System
Capillaries
Also called
exchange
vessels
Exchange materials between blood and tissues
Materials include dissolved gases, nutrients, waste products
Slide5Figure
20-1 An Overview of the Cardiovascular System.
Pulmonary arteries
Pulmonary veins
Systemic arteries
Systemic veins
Pulmonary Circuit
Systemic Circuit
Capillaries
in lungs
Right
atrium
Right
ventricle
Capillaries
in trunk
and
lower
limbs
Capillaries
in head,neck, upperlimbs
Leftatrium
Left
ventricle
Slide6An Introduction to the Cardiovascular System
Four Chambers of the Heart
Right
atrium
Collects blood from systemic circuit
Right
ventricle
Pumps blood to pulmonary circuit
Left
atrium
Collects blood from pulmonary circuit
Left
ventricle
Pumps blood to systemic circuit
Slide720-1 Anatomy of the Heart
The Heart
Great veins and arteries at the base
Pointed tip is
apex
Surrounded by pericardial sac
Sits between two pleural cavities in the
mediastinum
Slide8Figure 20-
2a The Location of the Heart in the Thoracic Cavity.
Trachea
First rib (cut)
Base of
heart
Right lung
Parietal
pericardium
(cut)
Thyroid
gland
Left lung
Apex of
heart
Diaphragm
An anterior view of the chest, showing the
position of the heart and major blood vessels
relative to the ribs, lungs, and diaphragm.
a
Slide920-1 Anatomy of the Heart
The
Pericardium
Double lining of the pericardial cavity
Visceral
pericardium
Inner layer of pericardium
Parietal
pericardium
Outer layer
Forms inner layer of
pericardial
sac
Slide1020-1 Anatomy of the Heart
The Pericardium
Pericardial cavity
Is between parietal and visceral layers
Contains
pericardial
fluid
Pericardial sac
Fibrous tissue
Surrounds and stabilizes heart
Slide11Figure 20-
2b The Location of the Heart in the Thoracic Cavity.
Esophagus
b
Right pleural cavity
Right
lung
Bronchus of lung
Right pulmonary
artery
Right pulmonary
vein
Posterior
mediastinum
Aortic
arch
Right atrium
Anterior mediastinum
Right ventricle
Superior vena cava
Sternum
Pericardial sac
Epicardium
Pericardial cavity
Left atrium
Left ventricle
Pulmonary trunk
Left pulmonary
vein
Left pleural
cavity
Left
lung
Left pulmonary artery
Aorta (arch
segment removed)
A superior view of the organs in the mediastinum; portions of the lungs have been removed to reveal
blood vessels and airways. The heart is located in the anterior part of the mediastinum, immediately
posterior to the sternum.
Slide12Figure 20-
2c The Location of the Heart in the Thoracic Cavity.
Balloon
c
Base of
heart
Fibrous
attachment to
diaphragm
Cut edge of
parietal pericardium
Fibrous tissue of
pericardial sac
Parietal pericardium
Areolar tissue
Mesothelium
Cut edge of
epicardium
Apex of heart
Wrist (corresponds
to base of heart)
Inner wall (corresponds
to
epicardium
)
Air space (corresponds
to pericardial cavity)
Outer wall (corresponds
to parietal pericardium)
The relationship between the heart and the pericardial cavity; compare with the fist-and-balloon example.
Slide1320-1 Anatomy of the Heart
Superficial Anatomy of the Heart
Atria
Thin-walled
Expandable outer
auricle
(
atrial
appendage
)
Slide1420-1 Anatomy of the Heart
Superficial Anatomy of the Heart
Sulci
Coronary
sulcus
divides atria and ventricles
Anterior
interventricular
sulcus
and
posterior
interventricular
sulcus
Separate left and right ventricles
Contain blood vessels of cardiac muscle
Slide15Figure 20-
3a The Position and Superficial Anatomy of the Heart.
1
a
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
Base of heart
Ribs
Apex of
heart
Heart position relative to the rib cage.
Slide16Figure 20-
3b The Position and Superficial Anatomy of the Heart.
Left
ventricle
b
Fat and vessels
in anterior
interventricular
sulcus
Auricle of
left atrium
Pulmonary
trunk
Left pulmonary
artery
Descending
aorta
Ligamentum
arteriosum
Arch of aorta
Left subclavian artery
Right
atrium
Right
ventricle
Superior
vena cava
Left common
carotid artery
Brachiocephalic
trunk
Ascending
aorta
Auricle
of right
atrium
Fat and
vessels incoronarysulcus
Major anatomical features on the anterior surface.
Slide17Figure 20-
3c The Position and Superficial Anatomy of the Heart.
Right
ventricle
c
Left subclavian artery
Left common carotid
artery
Brachiocephalic trunk
Ascending
aorta
Superior
vena cava
Auricle of
right atrium
Right atrium
Right
coronary
artery
Coronary sulcus
Ligamentum
arteriosum
Left pulmonary
artery
Pulmonary
trunk
Auricle of left atrium
Left coronary artery
(LCA)
Anterior
interventricular
sulcus
Left
ventricle
Anterior
interventricular
branch of LCA
Marginal branch
of right coronary artery
Anterior surface of the heart, cadaver dissection.
Slide18Figure 20-
3d The Position and Superficial Anatomy of the Heart.
Left
ventricle
d
Left
atrium
Right
ventricle
Right
atrium
Left pulmonary artery
Left pulmonary veins
Fat and vessels
in coronary
sulcus
Coronary
sinus
Arch of aorta
Right pulmonary
artery
Superior
vena cava
Right
pulmonary
veins
(superior
and inferior)
Inferior
vena cava
Fat and vessels in posteriorinterventricular sulcus
Major landmarks on the posterior surface. Coronaryarteries (which supply the heart itself) are shown inred; coronary veins are shown in blue.
Slide1920-1 Anatomy of the Heart
The Heart Wall
Epicardium
Myocardium
Endocardium
Slide2020-1 Anatomy of the Heart
Epicardium
(Outer Layer)
Visceral pericardium
Covers the heart
Slide2120-1 Anatomy of the Heart
Myocardium
(Middle Layer)
Muscular wall of the heart
Concentric layers of cardiac muscle tissue
Atrial myocardium wraps around great vessels
Two divisions of ventricular myocardium
Endocardium
(Inner Layer)
Simple squamous epithelium
Slide22Figure 20-
4a The Heart Wall.
Artery
a
Vein
Parietal
pericardium
Dense fibrous layer
Areolar tissue
Mesothelium
Epicardium
(visceral
pericardium)
Mesothelium
Areolar tissue
Endocardium
Areolar tissue
Endothelium
Myocardium
(cardiac muscle tissue)
Cardiac muscle cells
Connective tissues
Pericardial
cavity
Heart wall
A diagrammatic section through the heart
wall, showing the relative positions of the
epicardium
, myocardium, and endocardium.
The proportions are not to scale; the
thickness of the myocardial wall has been
greatly reduced.
Slide23Figure 20-
4b The Heart Wall.
Cardiac muscle tissue
forms concentric layers that
wrap around the atria or spiral
within the walls of the ventricles.
Ventricularmusculature
Atrialmusculature
b
Slide2420-1 Anatomy of the Heart
Cardiac Muscle Tissue
Intercalated
discs
Interconnect
cardiac
muscle
cells
Secured by desmosomes
Linked by gap junctions
Convey force of contraction
Propagate action potentials
Slide25Figure 20-
5a Cardiac Muscle Cells.
Nucleus
a
Cardiac muscle
cell (sectioned)
Bundles of
myofibrils
Intercalated
discs
Cardiac muscle cells
Cardiac muscle
cell
Mitochondria
Intercalated
disc (sectioned)
Slide26Figure 20-
5b Cardiac Muscle Cells.
b
Structure of an intercalated disc
Desmosomes
Intercalated disc
Gap junction
Z-lines bound to
opposing plasma
membranes
Slide27Figure 20-
5c Cardiac Muscle Cells.
c
Intercalated
discs
LM x 575
Cardiac muscle tissue
Cardiac muscle tissue
Slide2820-1 Anatomy of the Heart
Characteristics of Cardiac Muscle Cells
Small size
Single, central nucleus
Branching interconnections between cells
Intercalated discs
Slide29Table
20-
1 Structural and Functional Differences between Cardiac Muscle Cells and Skeletal Muscle Fibers.
Slide3020-1 Anatomy of the Heart
Internal Anatomy and Organization
Interatrial
septum
separates atria
Interventricular
septum
separates ventricles
Slide3120-1 Anatomy of the Heart
Internal Anatomy and Organization
Atrioventricular
(
AV
)
valves
Connect right atrium to right ventricle and left atrium to left ventricle
Are folds of fibrous tissue that extend into openings between atria and ventricles
Permit blood flow in one direction
From atria to ventricles
Slide3220-1 Anatomy of the Heart
The Right Atrium
Superior
vena
cava
Receives blood from head, neck, upper limbs, and chest
Inferior
vena
cava
Receives blood from trunk, viscera, and lower limbs
Coronary
sinus
Cardiac veins return blood to coronary sinus
Coronary sinus opens into right atrium
Slide3320-1 Anatomy of the Heart
The Right Atrium
Foramen
ovale
Before birth, is an opening through
interatrial
septum
Connects the two atria
Seals off at birth, forming
fossa
ovalis
Slide3420-1 Anatomy of the Heart
The Right Atrium
Pectinate
muscles
Contain prominent muscular ridges
On anterior atrial wall and inner surfaces of right auricle
Slide35Figure 20-
6a The Sectional Anatomy of the Heart.
Aortic arch
a
Brachiocephalic
trunk
Superior
vena cava
Right
pulmonary
arteries
Ascending aorta
Fossa
ovalis
Left common carotid artery
Left subclavian artery
Ligamentum
arteriosum
Pulmonary trunk
Pulmonary valve
Left pulmonary
arteries
Left pulmonary
veins
Left
atrium
Interatrial
septum
Aortic valve
Cusp of left AV
(mitral) valve
Left ventricle
Interventricular
septum
Opening of
coronary sinus
Right atrium
Pectinate
muscles
Conus
arteriosus
Cusp of right AV
(tricuspid) valve
Chordae
tendineae
Trabeculae
carneae
Moderator band
Descending aorta
Papillary muscles
Right ventricle
Inferior vena cava
A diagrammatic frontal section through the heart, showing
major landmarks and the path of blood flow (marked by
arrows) through the atria, ventricles, and associated vessels.
Slide36Figure 20-
6c The Sectional Anatomy of the Heart.
Right atrium
c
Left
subclavian
artery
Left common carotid artery
Brachiocephalic trunk
Superior vena cava
Ascending aorta
Cusps of right AV
(tricuspid) valve
Trabeculae
carneae
Right ventricle
Pulmonary
trunk
Cusp of
pulmonary valve
Auricle of left atrium
Cusp of left AV
(bicuspid) valve
Chordae
tendineae
Papillary muscles
Left ventricle
Interventricular
septum
Anterior view of a frontally sectioned
heart showing internal features and valves.
Slide3720-1 Anatomy of the Heart
The Right Ventricle
Free edges attach to
chordae
tendineae
from
papillary
muscles
of ventricle
Prevent valve from opening backward
Right
atrioventricular
(
AV
)
valve
Also called
tricuspid
valve
Opening from right atrium to right ventricle
Has three cusps
Prevents backflow
Slide3820-1 Anatomy of the Heart
The Right Ventricle
Trabeculae
carneae
Muscular ridges on internal surface of right (and left) ventricle
Includes
moderator
band
Ridge contains part of
conducting
system
Coordinates contractions of cardiac muscle cells
Slide39Figure 20-
6b
The Sectional Anatomy of the Heart.
Chordae
tendineae
b
Papillary muscles
The papillary muscles and chordae
tendineae
support the right AV (tricuspid)
valve. The photograph was taken from
inside the right ventricle, looking toward
a light shining from the right atrium.
Slide4020-1 Anatomy of the Heart
The Pulmonary Circuit
Conus
arteriosus
(superior end of right ventricle) leads to
pulmonary
trunk
Pulmonary trunk divides into
left
and
right
pulmonary
arteries
Blood flows from right ventricle to pulmonary trunk through
pulmonary
valve
Pulmonary valve has three semilunar cusps
Slide4120-1 Anatomy of the Heart
The Left Atrium
Blood gathers into
left
and
right
pulmonary
veins
Pulmonary veins deliver to left atrium
Blood from left atrium passes to
left
ventricle through left
atrioventricular
(
AV
)
valve
A two-cusped
bicuspid
valve
or
mitral
valve
Slide4220-1 Anatomy of the Heart
The Left Ventricle
Holds same volume as right ventricle
Is larger; muscle is thicker and more powerful
Similar internally to right ventricle but does
not
have moderator band
Slide4320-1 Anatomy of the Heart
The Left Ventricle
Systemic circulation
Blood leaves left ventricle through
aortic
valve
into
ascending
aorta
Ascending aorta turns (
aortic
arch
) and becomes
descending
aorta
Slide44Figure 20-
6c The Sectional Anatomy of the Heart.
Right atrium
c
Left
subclavian
artery
Left common carotid artery
Brachiocephalic trunk
Superior vena cava
Ascending aorta
Cusps of right AV
(tricuspid) valve
Trabeculae
carneae
Right ventricle
Pulmonary
trunk
Cusp of
pulmonary valve
Auricle of left atrium
Cusp of left AV
(bicuspid) valve
Chordae
tendineae
Papillary muscles
Left ventricle
Interventricular
septum
Anterior view of a frontally sectioned
heart showing internal features and valves.
Slide4520-1 Anatomy of the Heart
Structural Differences between the Left and Right Ventricles
Right ventricle wall is thinner, develops less pressure than left ventricle
Right ventricle is pouch-shaped, left ventricle is round
Slide46Figure 20-
7a Structural Differences between the Left and Right Ventricles.
Left
ventricle
a
Posterior
interventricular
sulcus
Right
ventricle
Fat in anterior
interventricular
sulcus
A diagrammatic sectional view through
the heart, showing the relative thicknesses
of the two ventricles. Notice the
pouchlike
shape of the right ventricle and the greater
thickness of the left ventricle.
Slide47Figure 20-
7b Structural Differences between the Left and Right Ventricles.
Left
ventricle
Right
ventricle
Dilated
Contracted
Diagrammatic views of theventricles just before acontraction (dilated) and justafter a contraction (contracted).
b
Slide4820-1 Anatomy of the Heart
The Heart Valves
Two pairs of one-way valves prevent backflow during contraction
Atrioventricular
(
AV
)
valves
Between atria and ventricles
Blood pressure closes valve cusps during ventricular contraction
Papillary muscles tense chordae
tendineae
to prevent valves from swinging into atria
Slide4920-1 Anatomy of the Heart
The Heart Valves
Semilunar valves
Pulmonary and aortic tricuspid valves
Prevent backflow from pulmonary trunk and aorta into ventricles
Have no muscular support
Three cusps support like tripod
Slide5020-1 Anatomy of the Heart
Aortic
Sinuses
At base of ascending aorta
Sacs that prevent valve cusps from sticking to aorta
Origin of right and left coronary arteries
Slide51Figure 20-
8a Valves of the Heart (Part 1 of 2).
Cardiac
skeleton
a
Transverse Sections, Superior View,
Atria and Vessels Removed
POSTERIOR
RIGHT
VENTRICLE
LEFT
VENTRICLE
Left AV (bicuspid)
valve (open)
Right AV
(tricuspid)
valve (open)
Aortic valve
(closed)
Pulmonary
valve (closed)
ANTERIOR
Relaxed ventricles
When the ventricles are relaxed, the AV valves are open and the semilunar valves are closed. The chordae tendineae are loose, and the papillary muscles are relaxed.
Aortic valve
closed
Slide52Figure 20-8a Valves of the Heart (Part
2 of 2).
Aortic valve
(closed)
Pulmonary
veins
LEFT
ATRIUM
Left AV (bicuspid)
valve (open)
Chordae
tendineae
(loose)
Papillary muscles
(relaxed)
LEFT VENTRICLE
(relaxed and filling
with blood)
Frontal Sections through Left Atrium and Ventricle
Relaxed ventricles
When the ventricles are relaxed, the AV valves are open
and the semilunar valves are closed. The chordae tendineae are loose, and the papillary muscles are relaxed.
a
Slide53Figure 20-
8b Valves of the Heart (Part 1 of 2).
b
Contracting ventricles
When the ventricles are contracting,
the AV valves are closed and the
semilunar valves are open. In the frontal section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles.
Aortic valve open
RIGHT
VENTRICLE
LEFT
VENTRICLE
Right AV
(tricuspid) valve
(closed)
Cardiac
skeleton
Left AV
(bicuspid) valve
(closed)
Aortic valve(open)
Pulmonary
valve (open)
Slide54Figure 20-
8b Valves of the Heart (Part 2 of 2).
b
Contracting ventricles
When the ventricles are contracting, the AV valves are
closed and the semilunar valves are open. In the frontal
section notice the attachment of the left AV valve to the chordae tendineae and papillary muscles.
Aorta
Aortic sinus
Aortic valve
(open)
LEFT
ATRIUM
Left AV (bicuspid)
valve (closed)
Chordae
tendineae
(tense)
Papillary muscles
(contracted)
Left ventricle
(contracted)
Slide5520-1 Anatomy of the Heart
Connective Tissues and the Cardiac Skeleton
Connective tissue fibers
Physically support cardiac muscle fibers
Distribute forces of contraction
Add strength and prevent overexpansion of heart
Provide elasticity that helps return heart to original size and shape after contraction
Slide5620-1 Anatomy of the Heart
The Blood Supply to the Heart
=
Coronary
circulation
Supplies blood to muscle tissue of heart
Coronary arteries and cardiac veins
Slide5720-1 Anatomy of the Heart
The
Coronary
Arteries
Left and right
Originate at aortic sinuses
High blood pressure, elastic rebound forces blood through coronary arteries between contractions
Slide5820-1 Anatomy of the Heart
Right
Coronary
Artery
Supplies blood to:
Right atrium
Portions of both ventricles
Cells of sinoatrial (SA) and
atrioventricular
nodes
Marginal
arteries
(surface of right ventricle)
Posterior
interventricular
artery
Slide5920-1 Anatomy of the Heart
Left Coronary Artery
Supplies blood to:
Left ventricle
Left atrium
Interventricular
septum
Slide6020-1 Anatomy of the Heart
Two Main Branches of Left Coronary Artery
Circumflex
artery
Anterior
interventricular
artery
Arterial
Anastomoses
Interconnect anterior and posterior
interventricular
arteries
Stabilize blood supply to cardiac muscle
Slide6120-1 Anatomy of the Heart
The Cardiac Veins
Great
cardiac
vein
Drains blood from area of anterior
interventricular
artery into coronary sinus
Anterior cardiac veins
Empty into right atrium
Posterior
cardiac
vein
,
middle
cardiac
vein
, and
small
cardiac
vein
Empty into great cardiac vein or coronary sinus
Slide62Figure 20-
9a The Coronary Circulation.
Aortic
arch
Ascending
aorta
Right
coronary
artery
Atrial
arteries
Anterior
cardiac
veins
Small
cardiac vein
Marginal
artery
Left coronary
artery
Pulmonary
trunk
Circumflex
artery
Anterior
interventricular
artery
Greatcardiacvein
Coronary vessels supplying and draining the anteriorsurface of the heart.
a
Slide63Figure 20-
9b The Coronary Circulation.
b
Coronary vessels supplying and draining
the posterior surface of the heart.
Left
ventricle
Marginal artery
Middle cardiac vein
Right
coronary
artery
Small
cardiac
vein
Coronary sinus
Circumflex artery
Great cardiac vein
Marginal artery
Posterior
interventricular
artery
Posterior
cardiac
vein
Slide64Figure 20-
9c The Coronary Circulation.
c
Auricle of
left atrium
Circumflex
artery
Great cardiac
vein
Marginal
artery
Posterior
cardiac vein
Posterior
interventricular
artery
Left pulmonary
veins
Left pulmonary
artery
Right
pulmonary
artery
Superior
vena cava
Right
pulmonary
veins
Left atrium
Right atrium
Inferior
vena cava
Coronary sinus
Middle cardiac vein
Right ventricle
A posterior view of the heart; the vessels have
been injected with colored latex (liquid rubber).
Slide65Figure 20-10 Heart Disease and Heart Attacks (Part
2 of 4).
Cross section
Cross section
Tunica
externa
Tunica
media
Lipid deposit
of plaque
Normal Artery
Narrowing of Artery
Slide6620-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Coronary
artery
disease
(
CAD
)
Areas of partial or complete blockage of coronary circulation
Cardiac muscle cells need a constant supply of oxygen and nutrients
Reduction in blood flow to heart muscle produces a corresponding reduction in cardiac performance
Reduced circulatory supply,
coronary
ischemia
, results from partial or complete blockage of coronary arteries
Slide6720-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Usual cause is formation of a fatty deposit, or
atherosclerotic
plaque
, in the wall of a coronary vessel
The plaque, or an associated
thrombus
(clot), then narrows the passageway and reduces blood flow
Spasms in smooth muscles of vessel wall can further decrease or stop blood flow
One of the first symptoms of CAD is commonly
angina
pectoris
Slide6820-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Angina
pectoris
In its most common form, a temporary ischemia develops when the workload of the heart increases
Although the individual may feel comfortable at rest, exertion or emotional stress can produce a sensation of pressure, chest constriction, and pain that may radiate from the sternal area to the arms, back, and neck
Slide6920-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Myocardial
infarction
(
MI
), or
heart
attack
Part of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygen
The death of affected tissue creates a nonfunctional area known as an
infarct
Heart attacks most commonly result from severe coronary artery disease (CAD)
Slide7020-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Myocardial
infarction
(
MI
), or
heart
attack
Pain does not always accompany a heart attack; therefore, the condition may go undiagnosed and may not be treated before a fatal MI occurs
A myocardial infarction can usually be diagnosed with an ECG and blood studies
Damaged myocardial cells release enzymes into the circulation, and these elevated enzymes can be measured in diagnostic blood tests
The enzymes include:
Cardiac
troponin
T
,
Cardiac troponin I
,
A special form of creatinine phosphokinase,
CK-MB
Slide7120-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
About 25 percent of MI patients die before obtaining medical assistance
65 percent of MI deaths among those under age 50 occur within an hour after the initial infarction
Slide7220-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
Risk factor modification
Stop smoking
High blood pressure treatment
Dietary modification to lower cholesterol and promote weight loss
Stress reduction
Increased physical activity (where appropriate)
Slide7320-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
Drug treatment
Drugs that reduce coagulation and therefore the risk of thrombosis, such as aspirin and
coumadin
Drugs that block sympathetic stimulation (
propranolol
or
metoprolol
)
Drugs that cause vasodilation, such as
nitroglycerin
Drugs that block calcium movement into the cardiac and vascular smooth muscle cells (calcium channel blockers)
In a myocardial infarction, drugs to relieve pain,
fibrinolytic
agents to help dissolve clots, and oxygen
Slide7420-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
Noninvasive surgery
Atherectomy
Blockage by a single, soft plaque may be reduced with the aid of a long, slender
catheter
inserted into a coronary artery to the plaque
Slide7520-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
Noninvasive surgery
Balloon
angioplasty
The tip of the catheter contains an inflatable balloon
Once in position, the balloon is inflated, pressing the plaque against the vessel walls
Because plaques commonly redevelop after angioplasty, a fine tubular wire mesh called a stent may be inserted into the vessel, holding it open
Slide7620-1 Anatomy of the Heart
Heart Disease – Coronary Artery Disease
Treatment of CAD and myocardial infarction
Coronary artery bypass graft (CABG)
In a coronary artery bypass graft, a small section is removed from either a small artery or a peripheral vein and is used to create a detour around the obstructed portion of a coronary artery
As many as four coronary arteries can be rerouted this way during a single operation
The procedures are named according to the number of vessels repaired, so we speak of single, double, triple, or quadruple coronary bypasses
Slide77Figure 20-10 Heart Disease and Heart
Attacks (Part 1 of 4).
Normal HeartA color-enhanced digitalsubtraction angiography (DSA)scan of a normal heart.
Advanced Coronary Artery Disease
A color-enhanced DSA scan showing
advanced coronary artery disease. Blood
flow to the ventricular myocardium is
severely restricted.
Slide78Figure 20-10 Heart Disease and Heart Attacks (Part
3 of 4).
Occluded
CoronaryArtery
Damaged
Heart
Muscle
Slide7920-2 The Conducting System
Heartbeat
A single contraction of the heart
The entire heart contracts in series
First the atria
Then the ventricles
Slide8020-2 The Conducting System
Cardiac Physiology
Two types of cardiac muscle cells
Conducting
system
Controls and coordinates heartbeat
Contractile
cells
Produce contractions that propel blood
Slide8120-2 The Conducting System
The Cardiac Cycle
Begins with action potential at SA node
Transmitted through conducting system
Produces action potentials in cardiac muscle cells (contractile cells)
Electrocardiogram
(
ECG
or
EKG
)
Electrical events in the cardiac cycle can be recorded on an electrocardiogram
Slide8220-2 The Conducting System
The
Conducting
System
A system of specialized cardiac muscle cells
Initiates and distributes electrical impulses that stimulate contraction
Automaticity
Cardiac muscle tissue contracts automatically
Slide8320-2 The Conducting System
Structures of the Conducting System
Sinoatrial
(
SA
)
node
– wall of right atrium
Atrioventricular
(
AV
)
node
– junction between atria and ventricles
Conducting
cells
– throughout myocardium
Slide8420-2 The Conducting System
Conducting Cells
Interconnect SA and AV nodes
Distribute stimulus through myocardium
In the atria
Internodal
pathways
In the ventricles
AV
bundle
and the
bundle
branches
Slide8520-2 The Conducting System
Prepotential
Also called
pacemaker
potential
Resting potential of conducting cells
Gradually depolarizes toward threshold
SA node depolarizes first, establishing heart rate
Slide86Figure 20-
11a The Conducting System of the Heart.
a
Sinoatrial
(SA) node
Internodal
pathways
Atrioventricular
(AV) node
AV bundle
Bundle
branches
Purkinje
fibers
Components of the
conducting system.
Slide87Figure 20-
11b The Conducting System of the Heart.
Threshold
Prepotential
Time (sec)
0
0.8
1.6
0 mV
b
+
20 mV
−
20 mV
−
40 mV
−
60 mV
Changes in the membrane potential of a pacemaker
cell in the SA node that is establishing a heart rate
of 72 beats per minute. Note the presence of a
prepotential
, a gradual spontaneous depolarization.
Slide8820-2 The Conducting System
Heart Rate
SA node generates 80–100 action potentials per minute
Parasympathetic stimulation slows heart rate
AV node generates 40–60 action potentials per minute
Slide8920-2 The Conducting System
The
Sinoatrial
(
SA
)
Node
In posterior wall of right atrium
Contains
pacemaker
cells
Connected to AV node by
internodal
pathways
Begins atrial activation (Step 1)
Slide90Figure 20-12 Impulse Conduction through the
Heart (Part 1 of 5).
SA
node
1
SA node activity andatrial activation begin.
Time
=
0
Slide9120-2 The Conducting System
The
Atrioventricular
(
AV
)
Node
In floor of right atrium
Receives impulse from SA node (Step 2)
Delays impulse (Step 3)
Atrial contraction begins
Slide92Figure 20-12 Impulse Conduction through the Heart (Part
2 of 5).
AV
node
2
Stimulus spreads across theatrial surfaces and reachesthe AV node.
Elapsed time
=
50
msec
Slide93Figure 20-12 Impulse Conduction through the Heart (Part
3 of 5).
AV
bundle
3
There is a 100-msec delay
at the AV node. Atrial
contraction begins.
Elapsed time = 150 msec
Bundle
branches
Slide9420-2 The Conducting System
The
AV
Bundle
In the septum
Carries impulse to
left
and
right
bundle
branches
Which conduct to Purkinje fibers (Step 4)
And to the moderator band
Which conducts to papillary muscles
Slide95Figure 20-12 Impulse Conduction through the Heart (Part
4 of 5).
Moderator
band
4
The impulse travels along theinterventricular septum withinthe AV bundle and the bundlebranches to the Purkinje fibersand, by the moderator band,to the papillary muscles of theright ventricle.
Elapsed time
=
175
msec
Slide9620-2 The Conducting System
Purkinje
Fibers
Distribute impulse through ventricles (Step 5)
Atrial contraction is completed
Ventricular contraction begins
Slide97Figure 20-12 Impulse Conduction through the Heart (Part
5 of 5).
Purkinje fibers
5
The impulse is distributed byPurkinje fibers and relayedthroughout the ventricularmyocardium. Atrial contractionis completed, and ventricularcontraction begins.
Elapsed time = 225 msec
Slide9820-2 The Conducting System
Abnormal Pacemaker Function
Bradycardia
– abnormally slow heart rate
Tachycardia
– abnormally fast heart rate
Ectopic
pacemaker
Abnormal cells
Generate high rate of action potentials
Bypass conducting system
Disrupt ventricular contractions
Slide9920-2 The Conducting System
The
Electrocardiogram
(
ECG
or
EKG
)
A recording of electrical events in the heart
Obtained by electrodes at specific body locations
Abnormal patterns diagnose damage
Slide10020-2 The Conducting System
Features of an ECG
P wave
Atria depolarize
QRS complex
Ventricles depolarize
T wave
Ventricles repolarize
Slide10120-2 The Conducting System
Time Intervals between ECG Waves
P–R interval
From start of atrial depolarization
To start of QRS complex
Q–T interval
From ventricular depolarization
To ventricular repolarization
Slide102Figure 20-
13a An Electrocardiogram.
a
Electrode placement for
recording a standard ECG.
Slide103Figure 20-
13b An Electrocardiogram.
b
P wave
(atria
depolarize)
P–R
interval
R
S
Q
T wave
(ventricles
repolarize)
S–T
interval
Q–T
interval
P–R segment
S–Tsegment
QRS interval(ventricles depolarize)
R
Millivolts
+1
+0.5
0
−0.5
An ECG printout is a strip of graph paper containing a record of the electrical eventsmonitored by the electrodes. The placement of electrodes on the body surface affectsthe size and shape of the waves recorded. The example is a normal ECG; the enlargedsection indicates the major components of the ECG and the measurements most oftentaken during clinical analysis.
800
msec
Slide104Figure 20-14 Cardiac
Arrhythmias (Part 1 of 2).
Premature Atrial Contractions (PACs)
Paroxysmal Atrial Tachycardia (PAR)
Atrial Fibrillation (AF)
Premature atrial contractions (PACs)often occur in healthy individuals. In a PAC,the normal atrial rhythm is momentarilyinterrupted by a “surprise” atrial contraction.Stress, caffeine, and various drugs may
P
P
P
P
P
P
P
P
P
increase the incidence of PACs, presumablyby increasing the permeabilities of the SApacemakers. The impulse spreads along theconduction pathway, and a normal ventricularcontraction follows the atrial beat.
In paroxysmal (par-ok-SIZ-mal) atrialtachycardia, or PAT, a premature atrial contraction triggers a flurry of atrial activity.The ventricles are still able to keep pace, and theheart rate jumps to about 180 beats per minute.
During atrial fibrillation (fib-ri-LĀ-shun), theimpulses move over the atrial surface at ratesof perhaps 500 beats per minute. The atrial wallquivers instead of producing an organizedcontraction. The ventricular rate cannot followthe atrial rate and may remain within normal
limits. Even though the atria are now
nonfunctional, their contribution to ventricular
end-diastolic volume (the maximum amount of
blood the ventricles can hold at the end of atrial
contraction) is so small that the condition may
go unnoticed in older individuals.
Slide105Figure 20-14 Cardiac Arrhythmias (Part
2 of 2).
Premature Ventricular Contractions (PVCs)
Ventricular Tachycardia (VT)
Ventricular Fibrillation (VF)
Premature ventricular contractions (PVCs)occur when a Purkinje cell or ventricularmyocardial cell depolarizes to threshold andtriggers a premature contraction. Single PVCs are common and not dangerous. The cell
P
P
P
P
T
T
T
responsible is called an ectopic pacemaker. The frequency of PVCs can be increased byexposure to epinephrine, to other stimulatorydrugs, or to ionic changes that depolarizecardiac muscle plasma membranes.
Ventricular fibrillation (VF) is responsible for the condition known ascardiac arrest. VF is rapidly fatal,because the ventricles quiver andstop pumping blood.
Ventricular tachycardia
is defined as four or
more PVCs without intervening normal beats. It
is also known as
VT
or
V-
tach
. Multiple PVCs
and VT may indicate that serious cardiac
problems exist.
Slide10620-2 The Conducting System
Contractile
Cells
Purkinje fibers distribute the stimulus to the contractile cells, which make up most of the muscle cells in the heart
Resting potential
Of a ventricular cell about –90 mV
Of an atrial cell about –80 mV
Slide107Figure 20-
15a The Action Potentials in Skeletal and Cardiac Muscle.
Stimulus
300
200
100
0
+
30
0
−
90
mV
Time (
msec
)
Relative
refractoryperiod
Absolute refractoryperiod
KEY
Absolute refractoryperiod
Relative refractoryperiod
Rapid Depolarization
Cause: Na+ entryDuration: 3–5 msecEnds with: Closure ofvoltage-gated fastsodium channels
The Plateau
Cause: Ca2+ entryDuration: ∼175 msecEnds with: Closure of slow calciumchannels
Repolarization
Cause: K+ lossDuration: 75 msecEnds with: Closure of slow potassiumchannels
1
2
3
1
2
3
a
Events in an action potential in a ventricular
muscle cell.
Slide108Figure 20-
15b The Action Potentials in Skeletal and Cardiac Muscle.
Contraction
Skeletal
muscle
Action
potential
Contraction
Cardiac
muscle
Action potential
Time (
msec)
Tension
Tension
Time (msec)
300
200
100
0
300
200
100
0
+30
0
−90
mV
+30
0
−85
mV
b
Action potentials and twitch contractions in a
skeletal muscle (above) and cardiac muscle (below).
The shaded areas indicate the durations of the absolute (blue) and relative (beige) refractory periods.
KEY
Absolute refractoryperiod
Relative refractory
period
Slide10920-2 The Conducting System
Refractory
Period
Absolute refractory period
Long
Cardiac muscle cells cannot respond
Relative refractory period
Short
Response depends on degree of stimulus
Slide11020-2 The Conducting System
Timing of Refractory Periods
Length of cardiac action potential in ventricular cell
250–300 msec
30 times longer than skeletal muscle fiber
Long refractory period prevents summation and tetany
Slide11120-2 The Conducting System
The Role of Calcium Ions in Cardiac Contractions
Contraction of a cardiac muscle cell
Is produced by an increase in calcium ion concentration around myofibrils
Slide11220-2 The Conducting System
The Energy for Cardiac Contractions
Aerobic energy of heart
From mitochondrial breakdown of fatty acids and glucose
Oxygen from circulating hemoglobin
Cardiac muscles store oxygen in myoglobin
Slide11320-3 The Cardiac Cycle
The
Cardiac
Cycle
Is the period between the start of one heartbeat and the beginning of the next
Includes both contraction and relaxation
Slide11420-3 The Cardiac Cycle
Two Phases of the Cardiac Cycle
Within any one chamber
Systole
(contraction)
Diastole
(relaxation)
Slide11520-3 The Cardiac Cycle
Blood Pressure
In any chamber
Rises during systole
Falls during diastole
Blood flows from high to low pressure
Controlled by timing of contractions
Directed by one-way valves
Slide11620-3 The Cardiac Cycle
Cardiac Cycle and Heart Rate
At 75 beats per minute (bpm)
Cardiac cycle lasts about 800 msec
When heart rate increases
All phases of cardiac cycle shorten, particularly diastole
Slide11720-3 The Cardiac Cycle
Phases of the Cardiac Cycle
Atrial systole
Atrial diastole
Ventricular systole
Ventricular diastole
Slide11820-3 The Cardiac Cycle
Atrial Systole
Atrial systole
Atrial contraction begins
Right and left AV valves are open
Atria eject blood into ventricles
Filling ventricles
Atrial systole ends
AV valves close
Ventricles contain maximum blood volume
Known as
end-diastolic
volume
(
EDV
)
Slide11920-3 The Cardiac Cycle
Ventricular Systole
Ventricles contract and build pressure
AV valves close causing
isovolumetric
contraction
Ventricular
ejection
Ventricular pressure exceeds vessel pressure opening the semilunar valves and allowing blood to leave the ventricle
Amount of blood ejected is called the
stroke
volume
(
SV
)
Slide12020-3 The Cardiac Cycle
Ventricular Systole
Ventricular pressure falls
Semilunar valves close
Ventricles contain
end-systolic
volume
(
ESV
), about 40 percent of end-diastolic volume
Slide12120-3 The Cardiac Cycle
Ventricular Diastole
Ventricular diastole
Ventricular pressure is higher than atrial pressure
All heart valves are closed
Ventricles relax (
isovolumetric
relaxation
)
Atrial pressure is higher than ventricular pressure
AV valves open
Passive atrial filling
Passive ventricular filling
Slide12220-3 The Cardiac Cycle
Heart Sounds
S
1
Loud sounds
Produced by AV valves
S
2
Loud sounds
Produced by semilunar valves
Slide12320-3 The Cardiac Cycle
S
3
, S
4
Soft sounds
Blood flow into ventricles and atrial contraction
Heart
Murmur
Sounds produced by regurgitation through valves
Slide124Figure 20-
18a Heart Sounds.
a
Aortic
valve
Sounds heard
Valve location
Pulmonary
valve
Valve location
Valve location
Valve location
Sounds heard
Sounds heard
Sounds heard
Left
AV
valve
Right
AV
valve
Placements of a stethoscope for
listening to the different sounds
produced by individual valves
Slide125Figure 20-
18b Heart Sounds.
Aorta
Semilunar
valves open
Semilunar
valves close
AV valves
close
AV valves
open
Left
atrium
Left
ventricle
120
Pressure(mm Hg)
90
60
30
0
Heart sounds
S4
“Lubb”
“Dupp”
S4
S1
S2
S3
The relationship between heart sounds and key events in thecardiac cycle
b
Slide12620-4 Cardiodynamics
Cardiodynamics
The movement and force generated by cardiac contractions
End-diastolic
volume
(
EDV
)
End-systolic
volume
(
ESV
)
Stroke
volume
(
SV
)
SV = EDV – ESV
Ejection
fraction
The percentage of EDV represented by SV
Slide12720-4 Cardiodynamics
Factors Affecting Cardiac Output
Cardiac output
Adjusted by changes in heart rate or stroke volume
Heart rate
Adjusted by autonomic nervous system or hormones
Stroke volume
Adjusted by changing EDV or ESV
Slide128Figure 20
-20 Factors Affecting Cardiac Output.
Hormones
Autonomicinnervation
End-diastolicvolume
End-systolicvolume
Factors AffectingHeart Rate (HR)
Factors AffectingStroke Volume (SV)
HEART RATE (HR)
STROKE VOLUME (SV) = EDV − ESV
CARDIAC OUTPUT (CO)
=
HR
×
SV
Slide12920-4 Cardiodynamics
Autonomic Innervation
Cardiac
plexuses
innervate heart
Vagus
nerves (N X) carry parasympathetic preganglionic fibers to small ganglia in cardiac plexus
Cardiac
centers
of medulla oblongata
Cardioacceleratory
center
controls sympathetic neurons (increases heart rate)
Cardioinhibitory
center
controls parasympathetic neurons (slows heart rate)
Slide13020-4 Cardiodynamics
Autonomic Innervation
Cardiac reflexes
Cardiac centers monitor:
Blood pressure (baroreceptors)
Arterial oxygen and carbon dioxide levels (chemoreceptors)
Cardiac centers adjust cardiac activity
Autonomic tone
Dual innervation maintains resting tone by releasing ACh and NE
Fine adjustments meet needs of other systems
Slide131Figure 20-21 Autonomic Innervation of the Heart.
Vagal nucleus
Medulla
oblongata
Vagus
(N X)
Spinal cord
Parasympathetic
Parasympathetic
preganglionic
fiber
Synapses in
cardiac plexus
Parasympathetic
postganglionic
fibers
Cardioinhibitory
center
Cardioacceleratory
center
Sympathetic
Sympathetic
preganglionic
fiber
Sympathetic ganglia
(cervical ganglia and
superior thoracic
ganglia [T
1
–T
4
])
Sympatheticpostganglionic fiber
Cardiac nerve
Slide13220-4 Cardiodynamics
Effects on the SA Node
Sympathetic and parasympathetic stimulation
Greatest at SA node (heart rate)
ACh (parasympathetic stimulation)
Slows the heart
NE (sympathetic stimulation)
Speeds the heart
Slide13320-4 Cardiodynamics
Atrial
Reflex
Also called
Bainbridge
reflex
Adjusts heart rate in response to
venous
return
Stretch receptors in right atrium
Trigger increase in heart rate
Through increased sympathetic activity
Slide13420-4 Cardiodynamics
Factors Affecting the Stroke Volume
The EDV – amount of blood a ventricle contains at the end of diastole
Filling
time
Duration of ventricular diastole
Venous
return
Rate of blood flow during ventricular diastole
Slide13520-4 Cardiodynamics
Preload
The degree of ventricular stretching during ventricular diastole
Directly proportional to EDV
Affects ability of muscle cells to produce tension
Slide13620-4 Cardiodynamics
The EDV and Stroke Volume
At rest
EDV is low
Myocardium stretches less
Stroke volume is low
With exercise
EDV increases
Myocardium stretches more
Stroke volume increases
Slide13720-4 Cardiodynamics
The
Frank–Starling
Principle
As EDV increases, stroke volume increases
Physical Limits
Ventricular expansion is limited by:
Myocardial connective tissue
The cardiac (fibrous) skeleton
The pericardial sac
Slide13820-4 Cardiodynamics
End-Systolic Volume (ESV)
Is the amount of blood that remains in the ventricle at the end of ventricular systole
Slide13920-4 Cardiodynamics
Three Factors That Affect ESV
Preload
Ventricular stretching during diastole
Contractility
Force produced during contraction, at a given preload
Afterload
Tension the ventricle produces to open the semilunar valve and eject blood
Slide14020-4 Cardiodynamics
Effects of Autonomic Activity on Contractility
Sympathetic stimulation
NE released by postganglionic fibers of cardiac nerves
Epinephrine and NE released by adrenal medullae
Causes ventricles to contract with more force
Increases ejection fraction and decreases ESV
Slide14120-4 Cardiodynamics
Effects of Autonomic Activity on Contractility
Parasympathetic activity
Acetylcholine released by vagus nerves
Reduces force of cardiac contractions
Slide14220-4 Cardiodynamics
Hormones
Many hormones affect heart contraction
Pharmaceutical drugs mimic hormone actions
Stimulate or block beta receptors
Affect calcium ions (e.g., calcium channel blockers)
Slide14320-4 Cardiodynamics
Afterload
Is increased by any factor that restricts arterial blood flow
As afterload increases, stroke volume decreases
Slide144Figure 20-23 Factors Affecting Stroke Volume.
Venous return (VR)
VR
= EDV
VR = EDV
Filling time (FT)
FT = EDV
FT = EDV
Contractility (Cont)of muscle cells
Cont = ESV
Cont = ESV
Afterload (AL)
AL = ESV
AL = ESV
ESV = SV
ESV = SV
EDV = SV
EDV = SV
Preload
Increased bysympatheticstimulation
Decreased byparasympatheticstimulation
Increased by E, NE,glucagon,thyroid hormones
Increased byvasoconstriction
Decreased byvasodilation
End-diastolicvolume (EDV)
End-systolicvolume (ESV)
Factors Affecting Stroke Volume (SV)
STROKE VOLUME (SV)
Slide14520-4 Cardiodynamics
The Heart and Cardiovascular System
Cardiovascular regulation
Ensures adequate circulation to body tissues
Cardiovascular centers
Control heart and peripheral blood vessels
Cardiovascular system responds to:
Changing activity patterns
Circulatory emergencies
Slide146Figure 20-
24a A Summary of the Factors Affecting Cardiac Output.
a
Maximum for
trained athletes
exercising atpeak levels
Normal rangeof cardiacoutput duringheavy exercise
Average restingcardiac output
Heart failure
Cardiac output (L/min)
40
35
30
25
20
15
10
5
0
Cardiac output varies widely
to meet metabolic demands
Slide147Figure 20-
24b A Summary of the Factors Affecting Cardiac Output.
Hormones
Autonomic
innervation
End-diastolic
volume
End-systolic
volume
Factors affectingheart rate (HR)
Factors affectingstroke volume (SV)
HEART RATE (HR)
STROKE VOLUME (SV) = EDV − ESV
CARDIAC OUTPUT (CO) = HR × SV
Hormones
Atrialreflex
Autonomicinnervation
Skeletalmuscleactivity
Bloodvolume
Changes inperipheralcirculation
Venousreturn
Fillingtime
Preload
Contractility
Vasodilationorvasoconstriction
Afterload
Factors affecting cardiac output
b