Download chapter 18-the heart

Midsternal line
2ndFigure
rib
18.1a Location of the
Sternum
heart in the mediastinum.
Diaphragm
Point of
maximal
intensity
(PMI)
Superior
vena cava
Aorta
Parietal
pleura (cut)
Figure
18.1c
Location
of
the
Pulmonary
Left lung
trunk heart in the mediastinum.
Pericardium
(cut)
Diaphragm
(c)
Apex of
heart
Pulmonary
trunk
Fibrous pericardium
Parietal layer of
serous pericardium
Pericardial cavity
Epicardium
(visceral layer
Heart
of serous
pericardium) wall
Figure 18.2 The pericardial
layers and layers of the heart
wall.
Myocardium
Pericardium
Myocardium
Endocardium
Heart chamber
Brachiocephalic trunk
Superior vena cava
Right pulmonary
artery
Left common carotid
artery
Left subclavian artery
Aortic arch
Ligamentum arteriosum
Left pulmonary artery
Ascending aorta
Pulmonary trunk
Left pulmonary veins
Right pulmonary
veins
Auricle of
left atrium
Figure 18.4b Gross anatomy
of the heart.
Right atrium
Circumflex artery
Right coronary artery
(in coronary sulcus)
Left coronary artery
(in coronary sulcus)
Anterior cardiac vein
Left ventricle
Right ventricle
Right marginal artery
Small cardiac vein
Inferior vena cava
(b) Anterior view
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
Apex
Aorta
Left pulmonary
artery
Superior vena cava
Left pulmonary
veins
Auricle of left
atrium
Right pulmonary veins
Right pulmonary artery
Right atrium
Figure 18.4d Gross anatomy
Left atrium
Inferior vena cava
of the heart. Coronary sinus
Great cardiac
vein
Posterior vein
of left ventricle
Left ventricle
Apex
Right coronary artery
(in coronary sulcus)
Posterior
interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
(d) Posterior surface view
Aorta
Superior vena cava
Right pulmonary
artery
Pulmonary trunk
Left pulmonary
artery
Left atrium
Left pulmonary
veins
Right atrium
Mitral (bicuspid)
Figure
18.4e
Gross
anatomy
Right pulmonary
valve
veins
Fossa ovalis
of the heart.
Aortic valve
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
(e) Frontal section
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular
septum
Epicardium
Myocardium
Endocardium
Pulmonary
Circuit
Capillary beds
of lungs where
gas exchange
occurs
Pulmonary veins
Aorta and branches
Pulmonary arteries
Figure 18.5 The systemic
Left atrium
and pulmonary circuits.
Left ventricle
Right atrium
Venae cavae
Right ventricle
Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
Heart
Systemic
Circuit
Capillary beds of all
body tissues where
gas exchange occurs
Aorta
Pulmonary
trunk
Left atrium
Superior
vena cava
Anastomosis
(junction of
vessels)
Right
atrium
Figure 18.7 Coronary
circulation.
Left
coronary
artery
Circumflex
artery
Superior
vena cava
Anterior
cardiac
veins
Right
coronary
artery
Left
ventricle
Right
ventricle
Anterior
Right
interventricular
marginal
artery
Posterior
artery
interventricular
artery
(a) The major coronary arteries
Great
cardiac
vein
Coronary
sinus
Small cardiac vein
(b) The major cardiac veins
Middle cardiac vein
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Figure 18.8a HeartTricuspid
valves.
(right atrioventricular)
valve
Mitral
(left atrioventricular)
valve
Aortic valve
Fibrous
skeleton
(a)
Pulmonary
valve
Anterior
Pulmonary
valve
Aortic
valve
Area of
cutaway
Mitral
valve
Tricuspid
valve
Figure 18.8c Heart valves.
Chordae tendineae
attached to tricuspid valve flap
(c)
Papillary
muscle
1 Blood returning to the
heart fills atria, putting
pressure against
atrioventricular valves;
atrioventricular valves are
forced open.
2 As ventricles fill,
atrioventricular valve flaps
hang limply into ventricles.
Direction of
blood flow
3 Atria contract, forcing
Chordae
tendineae
Atrium
Cusp of
atrioventricular
valve (open)
Figure 18.9 The
atrioventricular valves.
additional blood into ventricles.
Ventricle
Papillary
muscle
(a) AV valves open; atrial pressure greater than ventricular pressure
Atrium
1 Ventricles contract, forcing
blood against atrioventricular
valve cusps.
Cusps of
atrioventricular
valve (closed)
2 Atrioventricular valves
close.
3 Papillary muscles
contract and chordae
tendineae tighten,
preventing valve flaps
from everting into atria.
(b) AV valves closed; atrial pressure less than ventricular pressure
Blood in
ventricle
Aorta
Pulmonary
trunk
As ventricles
contract and
intraventricular
pressure rises,
blood is pushed up
against semilunar
valves, forcing them
open.
(a) Semilunar valves open
Figure 18.10 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.
(b) Semilunar valves closed
Aorta
Pulmonary
trunk
As ventricles
contract and
intraventricular
pressure rises,
blood is pushed up
against semilunar
valves, forcing them
open.
(a) Semilunar valves open
Figure 18.10a 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
Superior vena cava
Right atrium
1 The sinoatrial
(SA) node
(pacemaker)
generates impulses.
Internodal pathway
Pacemaker potential
SA node
Figure 18.14 Cardiac intrinsic
conduction system and action
potential succession during
one heartbeat.
2 The impulses
Left atrium
pause (0.1 s) at the
atrioventricular
(AV) node.
3 The
atrioventricular
(AV) bundle
connects the atria
to the ventricles.
4 The bundle branches
conduct the impulses
through the
interventricular septum.
5 The Purkinje fibers
depolarize the contractile
cells of both ventricles.
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation
Atrial muscle
Purkinje
fibers
AV node
Interventricular
septum
Ventricular
muscle
Pacemaker
potential
Plateau
Milliseconds
(b) Comparison of action potential shape at
various locations
Superior vena cava
Right atrium
1 The sinoatrial (SA)
node (pacemaker)
generates impulses.
Internodal pathway
2 The impulses
Left atrium
pause (0.1 s) at the
atrioventricular
(AV) node.
3 The atrioventricular
(AV) bundle
connects the atria
to the ventricles.
Purkinje
fibers
4 The bundle branches
conduct the impulses
through the
interventricular septum.
5 The Purkinje fibers
Interventricular
septum
depolarize the contractile
cells of both ventricles.
(a) Anatomy of the intrinsic conduction system showing the
sequence of electrical excitation
Nucleus
(a)
Intercalated discs Cardiac muscle cell
Gap junctions
Desmosomes
Figure 18.11 Microscopic
anatomy of cardiac muscle.
Cardiac muscle cell
Intercalated
disc
Mitochondrion Nucleus
Mitochondrion
T tubule
Sarcoplasmic
reticulum
(b)
Z disc
Nucleus
Sarcolemma
I band
A band
I band
QRS complex
Sinoatrial
node
Ventricular
depolarization
Ventricular
repolarization
Figure
18.16 An
Atrial
depolarization
electrocardiogram tracing
(lead I).
Atrioventricular
node
P-Q
Interval
S-T
Segment
Q-T
Interval
SA node
Depolarization
R
Repolarization
R
T
P
T
P
Q
S
1 Atrial depolarization, initiated
by the SA node, causes the
P wave.
R
AV node
Q
S
4 Ventricular depolarization
is complete.
R
T
P
T
P
Q
S
2 With atrial depolarization
complete, the impulse is
delayed at the AV node.
R
Q
S
5 Ventricular repolarization
begins at apex, causing the
T wave.
R
T
P
T
P
Q
S
3 Ventricular depolarization
begins at apex, causing the
QRS complex. Atrial
repolarization occurs.
Q
S
6 Ventricular repolarization
is complete.