Download Left ventricle - Dr. Par Mohammadian

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prepared by
Barbara Heard,
Atlantic Cape Community
College
CHAPTER
18
The
Cardiovascular
System: Modified
by Dr. Par
Mohammadian
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Heart Anatomy
• Approximately size of fist
• Location:
– In mediastinum (medial cavity of the thorax)
between 2nd rib and 5th intercostal space
– On superior surface of diaphragm
– Two-thirds of heart to left of midsternal line
– Anterior to vertebral column, posterior to
sternum
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Heart Anatomy
• Base (posterior surface) leans toward right
shoulder
• Apex points toward left hip
• Apical impulse palpated between fifth
and sixth ribs, just below left nipple
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Heart Anatomy
Coverings of the Heart: Physiology
The pericardium: A double-walled sac around the
heart
– Protects and anchors the heart
– Prevents overfilling of the heart with blood
– Allows for the heart to work in a relatively frictionfree environment
Coverings of the Heart: Anatomy
• Pericardium is composed of:
– A superficial fibrous pericardium
– A deep two-layer serous pericardium
• The parietal layer lines the internal surface of the fibrous
pericardium
• The visceral layer or epicardium lines the surface of the heart
• They are separated by the fluid-filled pericardial cavity
Pulmonary
trunk
Fibrous pericardium
Pericardium
Parietal layer of serous
pericardium
Myocardium
Pericardial cavity
Epicardium (visceral
layer of serous
pericardium)
Myocardium
Endocardium
Heart chamber
Heart
wall
Layers of the Heart Wall
• Three layers of heart wall:
– Epicardium
– Myocardium
– Endocardium
• Epicardium
– Visceral layer of serous pericardium
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Layers of the Heart Wall
• Myocardium (heart muscle)
– Contractile cardiac muscle cells
– Crisscrossing (circular & or spiral bundles), interlacing layer
of connective tissue that connect all parts of the heart
together.
Cardiac
muscle
bundles
Layers of the Heart Wall
Fibrous cardiac skeleton: Anchors cardiac muscle fibers
Supports great vessels and valves from becoming
stretched (caused by continuous stress of blood pulsing
through them).
Not electrically excitable => Limits spread of action
potentials to specific paths
• Endocardium (inside the heart) located on the inner
myocardial surface, lines the heart chambers, covers the
fibrous skeleton
• Continuous with the endothelial linings of blood vessels
leaving and entering the heart.
Chambers
• Four chambers:
– Two superior atria
– Two inferior ventricles
• Interatrial septum – separates atria
• Interventricular septum – separates ventricles
Figure 18.5e Gross anatomy of the heart.
Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Right pulmonary veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Frontal section
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Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
Chambers and Associated Great Vessels
• Coronary sulcus (AV- atrioventricular
groove)
– Encircles junction of atria and ventricles
• Anterior interventricular sulcus
– Anterior position of interventricular septum
• Posterior interventricular sulcus
– Landmark on posteroinferior surface
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Aorta
Superior vena cava
Left pulmonary artery
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Auricle of left atrium
Left atrium
Great cardiac vein
Posterior vein of
left ventricle
Left ventricle
Apex
Posterior surface view
Right atrium
Inferior vena cava
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
Figure 18.5b Gross anatomy of the heart.
Brachiocephalic trunk
Superior vena cava
Right pulmonary artery
Ascending aorta
Pulmonary trunk
Right pulmonary veins
Left common carotid artery
Left subclavian artery
Aortic arch
Ligamentum arteriosum
Left pulmonary artery
Left pulmonary veins
Auricle of
left atrium
Right atrium
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Right ventricle
Circumflex artery
Right marginal artery
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
Apex
Small cardiac vein
Inferior vena cava
Anterior view
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Left coronary artery
(in coronary sulcus)
Left ventricle
Atria: The Receiving Chambers
• Auricles
– Small, wrinkled appendages that increase atrial volume
• Right atrium
– Pectinate muscles (= teeth of the comb; muscle tissues
form ridges in the wall)
– Posterior and anterior regions separated by C shaped ridge
- crista terminalis
• Left atrium
– Smooth & Pectinate muscles found only in auricles
– fossa ovalis: marks the spot where an opening, the
foramen ovale, existed in the fetal heart.
Atria: The Receiving Chambers
• Small, thin-walled
• Contribute little to propulsion of blood
• Three veins empty into right atrium:
– Superior vena cava,
– Inferior vena cava,
– Coronary sinus (collects blood draining from the myocardium)
• Four pulmonary veins empty into left atrium
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Ventricles: The Discharging Chambers
• Most of the volume of heart
• Right ventricle - most of anterior
surface
• Left ventricle – posteroinferior surface
• Trabeculae carneae – irregular ridges
of muscle on walls
• Papillary muscles – anchor chordae
tendineae, which play a role in valve
function
Ventricles: The Discharging Chambers
• Thicker walls than atria
• Actual pumps of heart
• Right ventricle
– Pumps blood into pulmonary trunk
• Left ventricle
– Pumps blood into aorta (largest artery in
body)
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Figure 18.5b Gross anatomy of the heart.
Brachiocephalic trunk
Left common carotid artery
Right pulmonary artery
Left subclavian artery
Aortic arch
Ligamentum arteriosum
Left pulmonary artery
Ascending aorta
Left pulmonary veins
Superior vena cava
Pulmonary trunk
Right pulmonary veins
Auricle of
left atrium
Right atrium
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Right ventricle
Circumflex artery
Right marginal artery
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
Apex
Small cardiac vein
Inferior vena cava
Anterior view
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Left coronary artery
(in coronary sulcus)
Left ventricle
Figure 18.5a Gross anatomy of the heart.
Aortic arch (fat covered)
Pulmonary trunk
Auricle of right atrium
Auricle of left atrium
Anterior interventricular
artery
Right ventricle
Apex of heart (left ventricle)
Anterior aspect (pericardium removed)
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Figure 18.5f Gross anatomy of the heart.
Superior vena cava
Ascending aorta (cut open)
Pulmonary trunk
Aortic valve
Right ventricle anterior
wall (retracted)
Opening to right
atrium
Pulmonary valve
Interventricular
septum (cut)
Left ventricle
Chordae tendineae
Papillary muscles
Trabeculae carneae
Right ventricle
Photograph; view similar to (e)
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Heart Valves
• Ensure unidirectional blood flow through heart
• Open and close in response to pressure changes
• Two atrioventricular (AV) valves
– Prevent backflow into atria when ventricles contract
– Tricuspid valve (right AV valve)
– Mitral valve (left AV valve, bicuspid valve)
– Chordae tendineae anchor cusps to papillary muscles
• Hold valve flaps in closed position
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Figure 18.7 The atrioventricular (AV) valves.
1 Blood returning to the heart fills
atria, pressing against the AV valves.
The increased pressure forces AV
valves open.
Direction of
blood flow
Atrium
2 As ventricles fill, AV valve flaps
hang limply into ventricles.
Cusp of
atrioventricular
valve (open)
Chordae
tendineae
3 Atria contract, forcing additional
blood into ventricles.
Ventricle
Papillary
muscle
AV valves open; atrial pressure greater than ventricular pressure
Atrium
1 Ventricles contract, forcing
blood against AV valve cusps.
2 AV valves close.
3 Papillary muscles contract and
chordae tendineae tighten,
preventing valve flaps from everting
into atria.
AV valves closed; atrial pressure less than ventricular pressure
Cusps of
atrioventricular
valve (closed)
Blood in
ventricle
Heart Valves
• Two semilunar (SL) valves
– Prevent backflow into ventricles when
ventricles relax
– Open and close in response to pressure
changes
– Aortic semilunar valve
– Pulmonary semilunar valve
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Figure 18.8 The semilunar (SL) valves.
Aorta
Pulmonary
trunk
As ventricles contract
and intraventricular
pressure rises, blood
is pushed up against
semilunar valves,
forcing them open.
Semilunar valves open
As ventricles relax
and intraventricular
pressure falls, blood
flows back from
arteries, filling the
cusps of semilunar
valves and forcing
them to close.
Semilunar valves closed
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Figure 18.6a Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
Cardiac
skeleton
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Anterior
Figure 18.6b Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
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Figure 18.6c Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Chordae tendineae attached
to tricuspid valve flap
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Papillary
muscle
Figure 18.6d Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Opening of inferior
vena cava
Tricuspid valve
Mitral valve
Chordae
tendineae
Myocardium
of right
ventricle
Interventricular
septum
Papillary
muscles
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Myocardium
of left ventricle
Pathway of Blood Through the Heart and
Lungs
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
Pathway of Blood Through the Heart and
Lungs
Coronary Circulation: Functional blood
supply to heart muscle itself
• The heart continuously filled with blood but this
blood does not nourish the heart tissues => left
& right coronary arteries arise from the base of
aorta & encircle the heart in the coronary sulcus.
 Delivered when heart relaxed
 Left ventricle receives most blood supply
 Arterial supply varies among individuals
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Coronary Circulation: Arteries
• Arteries arise from base of aorta
• Left coronary artery branches 
– anterior interventricular artery
– circumflex artery
Supplies interventricular septum, anterior ventricular walls,
left atrium, and posterior wall of left ventricle
• Right coronary artery branches 
– right marginal artery
– posterior interventricular artery
Supplies right atrium and most of right ventricle
Figure 18.11a Coronary circulation.
Aorta
Pulmonary
trunk
Left atrium
Superior
vena cava
Anastomosis
(junction of
vessels)
Left
coronary
artery
Right
atrium
Right
coronary
artery
Right
ventricle
Right
marginal
artery
Circumflex
artery
Posterior
interventricular
artery
The major coronary arteries
Left
ventricle
Anterior
interventricular
artery
Coronary Circulation: Veins
• Cardiac veins: Collect blood from capillary beds
• Coronary sinus empties into right atrium;
formed by merging cardiac veins
– Great cardiac vein of anterior interventricular sulcus
– Middle cardiac vein in posterior interventricular
sulcus
– Small cardiac vein from inferior margin
• Several anterior cardiac veins empty directly
into right atrium anteriorly
Figure 18.11b Coronary circulation.
Superior
vena cava
Anterior
cardiac
veins
Great
cardiac
vein
Coronary
sinus
Small
cardiac vein
The major cardiac veins
Middle cardiac vein
Microscopic Anatomy of Cardiac Muscle
Nucleus
Intercalated
discs
Cardiac
muscle cell
• Cardiac muscle cells
striated, short, branched,
fat, interconnected
• T tubules wide, less
numerous; SR simpler
than in skeletal muscle
• Numerous large
mitochondria (25–35% of
cell volume)
Microscopic Anatomy of Cardiac Muscle
• Intercalated discs - junctions between cells - anchor cardiac cells
– Desmosomes prevent cells from separating during contraction
– Gap junctions allow ions to pass from cell to cell; electrically couple
adjacent cells
• Allows heart to behave as single coordinated unit
Nucleus
Intercalated
discs
Cardiac
muscle cell
Gap junctions
Desmosomes
Figure 18.12b Microscopic anatomy of cardiac muscle.
Cardiac muscle
cell
Intercalated
disc
Mitochondrion Nucleus
Mitochondrion
T tubule
Sarcoplasmic
reticulum
Z disc
Nucleus
Sarcolemma
I band
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A band
I band