1. Figure 18.1a Location of the heart in the mediastinum.
Midsternal line
Figure 18.1a Location of the heart in the mediastinum.
2nd rib
Sternum
Diaphragm
Point of
maximal
intensity
(PMI)

2. Figure 18.1c Location of the heart in the mediastinum.
Superior
vena cava
Aorta
Figure 18.1c Location of the heart in the mediastinum.
Parietal
pleura (cut)
Pulmonary
trunk
Left lung
Pericardium
(cut)
Apex of
heart
Diaphragm
(c)

3. Figure 18.2 The pericardial layers and layers of the heart wall.
Pulmonary
trunk
Fibrous pericardium
Figure The pericardial layers and layers of the heart wall.
Parietal layer of
serous pericardium
Pericardium
Pericardial cavity
Myocardium
Epicardium
(visceral layer
of serous
pericardium)
Heart
wall
Myocardium
Endocardium
Heart chamber

5. Figure 18.4b Gross anatomy of the heart.
Left common carotid
artery
Brachiocephalic trunk
Left subclavian artery
Superior vena cava
Aortic arch
Ligamentum arteriosum
Right pulmonary
artery
Left pulmonary artery
Ascending aorta
Figure 18.4b Gross anatomy of the heart.
Left pulmonary veins
Pulmonary trunk
Right pulmonary
veins
Auricle of
left atrium
Circumflex artery
Right atrium
Left coronary artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Left ventricle
Right ventricle
Great cardiac vein
Right marginal artery
Anterior interventricular
artery (in anterior
interventricular sulcus)
Small cardiac vein
Inferior vena cava
Apex
(b) Anterior view

6. Figure 18.4d Gross anatomy of the heart.
Aorta
Superior vena cava
Left pulmonary
artery
Right pulmonary artery
Right pulmonary veins
Left pulmonary
veins
Figure 18.4d Gross anatomy of the heart.
Auricle of left
atrium
Right atrium
Left atrium
Inferior vena cava
Great cardiac
vein
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior vein
of left ventricle
Posterior
interventricular
artery (in posterior
interventricular sulcus)
Left ventricle
Apex
Middle cardiac vein
Right ventricle
(d) Posterior surface view

7. Figure 18.4e Gross anatomy of the heart.
Aorta
Left pulmonary
artery
Superior vena cava
Right pulmonary
artery
Left atrium
Left pulmonary
veins
Pulmonary trunk
Figure 18.4e Gross anatomy of the heart.
Right atrium
Mitral (bicuspid)
valve
Right pulmonary
veins
Fossa ovalis
Aortic valve
Pectinate muscles
Pulmonary valve
Tricuspid valve
Left ventricle
Right ventricle
Papillary muscle
Chordae tendineae
Interventricular
septum
Trabeculae carneae
Epicardium
Inferior vena cava
Myocardium
Endocardium
(e) Frontal section

9. Figure 18.5 The systemic and pulmonary circuits.
Capillary beds
of lungs where
gas exchange
occurs
Pulmonary
Circuit
Pulmonary veins
Pulmonary arteries
Figure The systemic and pulmonary circuits.
Aorta and branches
Venae cavae
Left atrium
Left ventricle
Right atrium
Heart
Right ventricle
Systemic
Circuit
Oxygen-rich,
CO2-poor blood
Capillary beds of all
body tissues where
gas exchange occurs
Oxygen-poor,
CO2-rich blood

11. Figure 18.7 Coronary circulation.
Aorta
Superior
vena cava
Pulmonary
trunk
Left atrium
Figure Coronary circulation.
Anastomosis
(junction of
vessels)
Superior
vena cava
Left
coronary
artery
Right
atrium
Circumflex
artery
Great
cardiac
vein
Anterior
cardiac
veins
Right
coronary
artery
Left
ventricle
Coronary
sinus
Right
ventricle
Anterior
interventricular
artery
Right
marginal
artery
Posterior
interventricular
artery
Small cardiac vein
Middle cardiac vein
(a) The major coronary arteries
(b) The major cardiac veins

12. Figure 18.8a Heart valves. Pulmonary valve Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Figure 18.8a Heart valves.
Tricuspid
(right atrioventricular)
valve
Mitral
(left atrioventricular)
valve
Aortic valve
Pulmonary
valve
Fibrous
skeleton
(a)
Anterior

13. Figure 18.8c Heart valves. Pulmonary valve Aortic valve Area of
cutaway
Figure 18.8c Heart valves.
Mitral
valve
Tricuspid
valve
Chordae tendineae
attached to tricuspid valve flap
Papillary
muscle
(c)

14. Figure 18.9 The atrioventricular valves.
Blood returning to the
heart fills atria, putting
pressure against
atrioventricular valves;
atrioventricular valves are
forced open. 1
Direction of
blood flow
Atrium
Cusp of
atrioventricular
valve (open)
As ventricles fill,
atrioventricular valve flaps
hang limply into ventricles. 2
Figure The atrioventricular valves.
Chordae
tendineae
Atria contract, forcing
additional blood into ventricles. 3
Papillary
muscle
Ventricle
(a) AV valves open; atrial pressure greater than ventricular pressure
Atrium
Ventricles contract, forcing
blood against atrioventricular
valve cusps. 1
Cusps of
atrioventricular
valve (closed)
Atrioventricular valves
close. 2
Blood in
ventricle
Papillary muscles
contract and chordae
tendineae tighten,
preventing valve flaps
from everting into atria. 3
(b) AV valves closed; atrial pressure less than ventricular pressure

15. Figure 18.10 The semilunar valves.
Aorta
Pulmonary
trunk
As ventricles
contract and
intraventricular
pressure rises,
blood is pushed up
against semilunar
valves, forcing them
open.
Figure The semilunar valves.
(a) 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.
(b) Semilunar valves closed

16. Figure 18.10a The semilunar valves.
Aorta
Pulmonary
trunk
Figure 18.10a The semilunar valves.
As ventricles
contract and
intraventricular
pressure rises,
blood is pushed up
against semilunar
valves, forcing them
open.
(a) Semilunar valves open

17. Figure 18.10b The semilunar valves.
As ventricles relax
and intraventricular
pressure falls, blood
flows back from
arteries, filling the
cusps of semilunar
valves and forcing
them to close.
Figure 18.10b The semilunar valves.
(b) Semilunar valves closed

18. Superior vena cava
Right atrium
The sinoatrial
(SA) node
(pacemaker)
generates impulses. 1
Pacemaker potential
Internodal pathway
Figure Cardiac intrinsic conduction system and action potential succession during one heartbeat.
Left atrium
SA node
The impulses
pause (0.1 s) at the
atrioventricular
(AV) node. 2
Atrial muscle
Purkinje
fibers
The
atrioventricular
(AV) bundle
connects the atria
to the ventricles. 3
AV node
Pacemaker
potential
Ventricular
muscle 4
The bundle branches
conduct the impulses
through the
interventricular septum.
Inter-
ventricular
septum
Plateau
The Purkinje fibers
depolarize the contractile
cells of both ventricles. 5
Milliseconds
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation
(b) Comparison of action potential shape at
various locations

19. (a) Anatomy of the intrinsic conduction system showing the
Superior vena cava
Right atrium
The sinoatrial (SA)
node (pacemaker)
generates impulses. 1
Internodal pathway
The impulses
pause (0.1 s) at the
atrioventricular
(AV) node. 2
Left atrium
The atrioventricular
(AV) bundle
connects the atria
to the ventricles. 3
Purkinje
fibers
The bundle branches
conduct the impulses
through the
interventricular septum. 4
Inter-
ventricular
septum
The Purkinje fibers
depolarize the contractile
cells of both ventricles. 5
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation

20. Figure 18.11 Microscopic anatomy of cardiac muscle.
Nucleus
Intercalated discs
Cardiac muscle cell
Gap junctions
Desmosomes
Figure Microscopic anatomy of cardiac muscle.
(a)
Cardiac muscle cell
Mitochondrion
Nucleus
Intercalated
disc
Mitochondrion
T tubule
Sarcoplasmic
reticulum
Z disc
Nucleus
Sarcolemma
(b)
I band
A band
I band

24. Figure 18.16 An electrocardiogram tracing (lead I).
QRS complex
Sinoatrial
node
Ventricular
depolarization
Figure An electrocardiogram tracing (lead I).
Ventricular
repolarization
Atrial
depolarization
Atrioventricular
node
S-T
Segment
P-Q
Interval
Q-T
Interval

25. Atrial depolarization, initiated by the SA node, causes the P wave. 1
Repolarization R P T Q P T S
Atrial depolarization, initiated
by the SA node, causes the
P wave. 1 Q S 4
Ventricular depolarization
is complete.
AV node R R P T P T Q S
With atrial depolarization
complete, the impulse is
delayed at the AV node. 2 Q S
Ventricular repolarization
begins at apex, causing the
T wave. 5 R R P T P T Q S Q 3
Ventricular depolarization
begins at apex, causing the
QRS complex. Atrial
repolarization occurs. S
Ventricular repolarization
is complete. 6