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19
The Heart
PowerPoint® Lecture Presentations prepared by
Leslie Hendon
University of Alabama, Birmingham
© 2014 Pearson Education, Inc.
I. Circuits and Chambers
The heart is a muscular double pump
A. Pulmonary circuit: Right side receives oxygen-poor blood from
the body and pumps it to the lungs
B. Systemic circuit: Left side receives oxygenated blood from lungs
and pumps throughout the body
Atria = Receive blood from the pulmonary and systemic circuit
Ventricles = Pump blood to the pulmonary and systemic circuit
© 2014 Pearson Education, Inc.
Pulmonary Circuit
Aorta and
branches
Pulmonary
arteries
Left
atrium
Right
atrium
Heart
Right
ventricle
Venae
cavae
Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
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Left
ventricle
Systemic Circuit
Pulmonary
veins
II. Location and Orientation within the Thorax
A. Healthy heart typically weighs 250–350 grams
B. Largest organ of the mediastinum - located between the lungs
C. Apex lies to the left of the midline
D. Base is the broad posterior surface
E. The Four “Corners”
► Superior right - at costal cartilage of third rib and sternum
► Inferior right - at costal cartilage of sixth rib lateral to sternum
► Superior left - at costal cartilage of second rib lateral to sternum
► Inferior left - lies in the fifth intercostal space
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Midsternal line
Rib 2
Superior
vena cava
Aorta
Parietal
pleura (cut)
Diaphragm
Pulmonary
trunk
Left lung
Pericardium
(cut)
Mediastinum
Apex of
heart
Heart
Diaphragm
Right lung
T8
Posterior
Mediastinum
Aorta
Superior
vena cava
Right auricle
of right atrium
Right
ventricle
Left lung
Fat in
epicardium
Rib 5
Pericardium
(cut)
Apex of
heart
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III. Membranes of the Heart
Pericardium - two primary layers
A. fibrous pericardium - strong layer of dense connective tissue
B. serous pericardium – reduces friction as heart beats
1. parietal layer = attached to the “wall” of cavity
2. visceral layer = attached to the heart surface (“organ”)
© 2014 Pearson Education, Inc.
Pulmonary
trunk
Pericardium
Myocardium
Fibrous pericardium
Parietal layer of serous
pericardium
Pericardial cavity
Epicardium (visceral
layer of serous
pericardium)
Myocardium
Endocardium
Heart chamber
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Heart
wall
IV. Layers of the Heart Wall
A. Epicardium - visceral layer of the serous pericardium (“upon”)
B. Myocardium - consists of cardiac muscle
1. cardiac muscle arranged in circular and spiral patterns
C. Endocardium – inner surface
1. endothelium resting on a layer of connective tissue
2. lines the internal walls of the heart
3. Continuous with endothelium of arteries and veins
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Cardiac
muscle
bundles
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V. Heart Chambers
A. Right and left atria - superior chambers
B. Right and left ventricles - inferior chambers
C. Internal divisions – septum wall between chambers
1. interventricular septa
2. interatrial septa
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Auricle of
left atrium
Right atrium
Left ventricle
Right ventricle
Anterior view
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Apex
VI. Right Atrium
A. Forms right border of heart
B. Receives oxygen-poor blood from systemic circuit through:
1. superior vena cava
2. inferior vena cava
3. coronary sinus (blood returning from veins of heart itself)
C. Pectinate muscles - ridges inside anterior of right atrium
D. Fossa ovalis - depression in interatrial septum
1. remnant of foramen ovale – hole between atria in fetal heart
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VII. Right Ventricle
A. Receives blood from right atrium through the right
atrioventricular valve (tricuspid valve)
B. Pumps blood into pulmonary circuit through pulmonary trunk
C. Features of the internal walls of right ventricle
► trabeculae carneae – “fishnet like” small cavities
► chordae tendineae – “strings” attached to the valve cusps
► papillary muscles – attached to the chordae
► pectinate muscle – normal “smooth-like” muscle of walls
D. Pulmonary semilunar valve (pulmonary valve)
1. Located at opening of right ventricle and pulmonary trunk
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VIII. Left Atrium
A. Forms the apex of the heart
B. Makes up heart’s posterior surface
C. Receives oxygen-rich blood from lungs through pulmonary veins
D. Opens into the left ventricle through
1. left atrioventricular valve (bicuspid valve)
a. mitral valve is another name for the left AV valve
E. Pumps blood through systemic circuit via
1. aortic semilunar valve (aortic valve)
© 2014 Pearson Education, Inc.
Brachiocephalic trunk
Superior vena cava
Right pulmonary artery
Ascending aorta
Pulmonary trunk
Right pulmonary veins
Right atrium
Right ventricle
Inferior vena cava
Anterior view
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Anterior view
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Left common carotid artery
Left subclavian artery
Aortic arch
Left pulmonary artery
Left pulmonary veins
Auricle of
left atrium
Left ventricle
Anterior view
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Apex
Anterior view
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Right atrium
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Frontal section
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Frontal section
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Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Frontal section
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Frontal section
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Auricle of left atrium
Right atrium
Left atrium
Left ventricle
Right ventricle
Apex
Inferior view; surface shown rests on the diaphragm.
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IX. Heart Valves—Valve Structure
A. Atrioventricular (AV) valves
1. between atria and ventricles
Right AV valve  tricuspid valve
Left AV valve  bicuspid (mitral) valve
B. Aortic and pulmonary valves
1. at junction of ventricles and great arteries
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Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic
valve
Pulmonary
valve
Anterior
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Direction of
blood flow
Atrium
Cusp of
atrioventricular
valve (open)
Chordae
tendineae
Ventricle
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Papillary
muscle
X. Pathway of Blood Through the Heart
superior/inferior vena cavae ►
right atrium ►
(tricsupid valve) ►
right ventricle ►
(pulmonary semilunar valve) ►
pulmonary trunk ►
LUNGS ►
pulmonary veins ►
left atrium ►
(bicuspid (mitral) valve) ►
left ventricle ►
(aortic semilunar valve) ►
aorta ► BODY
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
XI. Structure of Heart Wall
A. Walls differ in thickness
1. atria = thin walls; ventricles = thick walls
2. left ventricle 3X thicker than right ventricle
a. exerts more pumping force (to the body!!)
Left venticle
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XII. Conduction System of the Heart
A. Cardiac muscle cells have intrinsic ability to:
1. generate and conduct impulses
2. signal these cells to contract rhythmically
SA node ►
AV node ►
AV Bundle (Bundle of His) ►
Bundle branches ►
Purkinje fibers
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Right atrium
sinoatrial (SA)
node (pacemaker cells)
atrioventricular
(AV) node
Left atrium
atrioventricular
(AV) bundle
bundle branches
Purkinje fibers
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Interventricular
septum
Right atrium
Left atrium
Interventricular
septum
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XIII. Innervation of the Heart
A. Parasympathetic fibers
1. branches of vagus nerve (X)
2. decrease heart rate
3. restricted to: SA node, AV node, coronary arteries
B. Sympathetic nerves
1. travel from cervical and upper thoracic chain ganglia
2. also SA node, AV node, coronary arteries
3. also innervate cardiac muscle throughout the heart
a. increase heart rate and strength of contraction
© 2014 Pearson Education, Inc.
Dorsal motor nucleus
of vagus
The vagus nerve
(parasympathetic)
decreases heart rate.
Cardioinhibitory
center
Cardioacceleratory
center
Medulla oblongata
Sympathetic
trunk
ganglion
Thoracic spinal cord
Sympathetic trunk
Sympathetic cardiac
nerves increase heart rate
and force of contraction.
AV
node
SA
node
Parasympathetic fibers
Sympathetic fibers
Interneurons
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XIV. Blood Supply to the Heart
A. Coronary arteries
1. right coronary artery
► branches to form the marginal artery
► later branches into the posterior interventricular artery
2. left coronary artery
► anterior interventricular artery and circumflex artery
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XV. Cardiac Veins
A. carry deoxygenated blood from the heart wall to the right atrium
B. occupy sulci (grooves) on the heart’s surface
C. Coronary sinus—runs in the posterior part of the coronary sulcus
1. Returns majority of venous blood from heart to the right
atrium
D. Three tributaries of coronary sinus
► great cardiac vein
► middle cardiac vein
► small cardiac vein
© 2014 Pearson Education, Inc.
Superior
vena cava
Aorta
Pulmonary trunk
Anastomosis
(junction of
vessels)
Left atrium
Left coronary
artery
Right atrium
Right
coronary
artery
Circumflex artery
Right ventricle
Anterior interventricular artery
Left ventricle
Right
marginal
artery
Posterior interventricular artery
The major coronary arteries
Superior
vena cava
Anterior
cardiac
veins
Small cardiac vein
The major cardiac veins
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Great cardiac vein
Coronary sinus
Middle cardiac vein