1. Chapter 22
Heart

2. Why have a heart?
Move nutrients and oxygen through the body.

3. How does the heart do its job?
First, get oxygen into the blood
Second, get oxygenated blood to the rest of the body

4. Location of heart Slightly left of center, posterior to sternum
Fig. 22.2
Location of heart
Slightly left of center, posterior to sternum
Rotated; right border sits anterior to left border
Base of heart is posterior and superior
formed by left atrium
Superior border
formed by ascending aorta, pulmonary trunk, superior vena cava
Conical bottom end is apex
Inferior border
formed by right ventricle
Superior border
2nd rib
Right border
Left border
Sternum
Diaphragm
Inferior border
(a) Borders of the heart

5. Location of heart From anterior view, right ventricle is most obvious
Fig. 22.2
Trachea
Location of heart
Right lung
Left lung
From anterior view, right ventricle is most obvious
Left ventricle sits behind
Aortic arch
Superior
vena cava
Pulmonary trunk
Ascending aorta
Right atrium
Left ventricle
Right ventricle
(b) Heart and lungs, anterior view

6. Blood flow
Fig. 22.6
Blood flows into the heart from the superior vena cava and the inferior vena cava
Superior vena cava carries blood from head, neck, arms, superior trunk
Inferior vena cava carries blood from lower limbs, inferior trunk
This blood is high in CO2 and low in O2
Superior vena cava
Pulmonary artery
Right atrium
Opening for inferior vena cava
Right ventricle
Inferior vena cava

7. Blood first enters the right atrium, then the right ventricle
Fig. 22.6
Blood first enters the right atrium, then the right ventricle
The right ventricle pumps blood out the pulmonary arteries to the lungs
In the lungs, the blood exchanges CO2 for O2
Superior vena cava
Pulmonary artery
Pulmonary artery
Pulmonary trunk
Right atrium
Opening for inferior vena cava
Right ventricle
Inferior vena cava

8. Flow and gas exchange in lungs is called pulmonary circulation
Fig. 22.1
Systemic
circulation 4
Flow and gas exchange in lungs is called pulmonary circulation
Lung
Lung
Basic pattern of blood flow 2 2
Pulmonary
circulation 1
Right side of heart
Right
side
Right
side 1 3 2
Lungs
Pulmonary
circulation
Oxygenated blood
Left
side
Left
side 3
Left side of heart
Deoxygenated blood
Heart
Gas exchange 4
Systemic cells 4
Systemic
circulation

9. Fig. 22.5b Heart, Posterior View
Blood returns to the heart through the pulmonary veins
The pulmonary veins empty into the left atrium
Fig. 22.5b Heart, Posterior View
Left pulmonary artery
Right pulmonary artery
Left pulmonary veins
Right pulmonary veins
Left atrium
Right atrium
Left ventricle
Right ventricle

10. The left atrium pumps blood into the left ventricle
The left ventricle pumps blood out the aorta to the body
Fig. 22.6
Aortic arch
Ascending aorta
Descending aorta
Left atrium
Right atrium
Left ventricle
Right ventricle

11. Fig. 22.6
Form and Function
What differences do you notice between the atria and the ventricles?
What’s different between the right and left ventricle?
Left atrium
Right atrium
Left ventricle
Right ventricle

12. Form and Function Atria do not make powerful contractions
Fig. 22.6
Atria do not make powerful contractions
Left ventricle makes more powerful contractions than right ventricle
How does the body ensure blood flows in only one direction?
Left atrium
Right atrium
Left ventricle
Right ventricle
Copyright © McGraw-Hill Education. Permission required for reproduction or display.

13. Valves Both atria fill at the same time, contract at the same time
Contraction of atria forces open valves between atria and ventricles
Right atrioventricular valve (AKA tricuspid valve) separates right atrium from right ventricle
Left atrioventricular valve (AKA bicuspid valve) separates left atrium from left ventricle

14. Valves
Fig. 22.7
Right atrioventricular valve (AKA tricuspid valve) separates right atrium from right ventricle
Left atrioventricular valve (AKA bicuspid valve) separates left atrium from left ventricle
Posterior
Left
atrioventricular
valve
Right
atrioventricular
valve
Aortic semilunar
valve
Fibrous
skeleton
Pulmonary
semilunar valve
Anterior

15. Valves
Left atrium
Atrioventricular valves are attached to inside of ventricles by chordae tendineae attached to papillary muscles inside ventricle
prevents inversion of valve flaps when ventricle contracts
typically 3 papillary muscles in right ventricle, 2 in left ventricle
Left
A/V valve
Right A/V valve
Chordae tendineae
Papillary muscles

16. Valves
Contraction of ventricles forces atrioventricular valves closed and opens semilunar valves

17. Valves
Fig. 22.7
Pulmonary semilunar valve separates right ventricle from pulmonary trunk
Aortic semilunar valve separates left ventricle from aorta
As ventricles relax, semilunar valves close
Posterior
Left
atrioventricular
valve
Right
atrioventricular
valve
Aortic semilunar
valve
Fibrous
skeleton
Pulmonary
semilunar valve
Anterior

18. Valves Semilunar valves don’t have chordae tendineae
Left
A/V valve
Pulmonary semilunar valve
Semilunar valves don’t have chordae tendineae
Cupped structure of valve fills with blood as ventricles contract, pushing valve back into place
Aortic semilunar valve
Right A/V valve
Chordae tendineae
Papillary muscles

19. Copyright © McGraw-Hill Education
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
(a) Ventricular Systole (Contraction)

20. Copyright © McGraw-Hill Education
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
(b) Ventricular Diastole (Relaxation)

21. Sounds of a heartbeat Lub-dub, lub-dub, lub-dub
“lub” is sound of atrioventricular valves closing
“dub” is sound of semilunar valves closing
Sounds are not heard best in exact spot of valve
Pulmonary semilunar valve
Aortic semilunar valve
Left atrioventricular valve
Right atrioventricular valve
Actual location of heart valve
Area where valve sound is best heard
Locations of individual heart valves and the ideal listening sites for each valve are shown.

22. Walls of heart chambers
Anterior walls of atria lined with muscular ridges called pectinate muscles (pecten = comb)
Increase strength of contraction with little increase in heart mass
Wall between atria is interatrial septum
Pectinate muscles
Interatrial
septum

23. Walls of heart chambers
Walls of ventricles have larger, more irregular muscular ridges called trabeculae carneae
Assist with contraction, pull on papillary muscles, prevent formation of vacuum during contraction
Wall between ventricles is interventricular septum
Trabeculae
carneae
Interventricular
septum

24. Heart wall structure Epicardium is visceral layer of pericardium
Fig. 22.3
Heart wall structure
Visceral layer of serous pericardium (epicardium)
Epicardium is visceral layer of pericardium
Myocardium: cardiac muscle
thickest layer
contracts to pump blood
Endocardium: innermost layer
simple squamous epithelium (AKA endothelium) and areolar connective tissue
Heart wall
Myocardium
Endocardium

25. Myocardium (cardiac muscle)
Fig. 22.4
Simple squamous
epithelium
Epicardium
(visceral layer of
serous pericardium)
Areolar connective
tissue and fat
Myocardium (cardiac muscle)
Areolar connective tissue
Endocardium
Endothelium

26. Fibrous skeleton of heart
Fig. 22.7
Dense regular connective tissue
Structural support between atria and ventricles
Anchor for heart valves
Rigid framework for attachment of cardiac muscle tissue
Electric insulator between ventricles
Posterior
Left
atrioventricular
valve
Right
A/V
valve
Aortic semilunar
valve
Fibrous
skeleton
Pulmonary
semilunar valve
Anterior

27. Pericardium Heart sits inside pericardium fibrous sac – very tough
Fig. 22.2
Pericardium
Mediastinum
Left lung
Heart sits inside pericardium
fibrous sac – very tough
serous lining made of two layers of epithelial tissue with tiny amount of water between
Ascending aorta
Pleura (cut)
Pericardium (cut)
Apex of heart
Diaphragm (cut)
(c) Serous membranes of the heart and lungs

28. Pericardium Restricts heart movement, prevents bouncing
Fig. 22.2
Pericardium
Posterior
Restricts heart movement, prevents bouncing
Prevents heart overfilling with blood
Thoracic vertebra
Right lung
Left lung
Aortic arch (cut)
Heart
Sternum
Anterior
(d) Cross-sectional view

29. Pericardium Outer layer is fibrous pericardium Fibrous pericardium
Fig. 22.3
Pericardium
Fibrous pericardium
Outer layer is fibrous pericardium
dense connective tissue
attached to diaphragm and base of aorta, pulmonary trunk, vena cava
Parietal layer of serous pericardium
Pericardial cavity
Visceral layer of serous pericardium
(epicardium)
Fibrous pericardium
Parietal layer of serous pericardium
Pericardial cavity

30. Pericardium Inner layer is serous pericardium Fibrous pericardium
Fig. 22.3
Pericardium
Inner layer is serous pericardium
double layer formed from single “balloon” stretched around heart
parietal layer connected to fibrous pericardium
pericardial cavity contains serous fluid secreted by serous membranes
visceral layer covers outside of heart (AKA epicardium)
Fibrous pericardium
Parietal layer of serous pericardium
Pericardial cavity
Visceral layer of serous pericardium
(epicardium)
Fibrous pericardium
Parietal layer of serous pericardium
Pericardial cavity

31. Pericarditis Inflammation of pericardium makes blood vessels leaky
Fig. 22.3
Pericarditis
Inflammation of pericardium makes blood vessels leaky
Fluid accumulates in pericardial cavity
prevents heart from pumping fully

32. External anatomy of heart
Fig. 22.5a
External anatomy of heart
Coronary sulcus extends around heart between atria and ventricles
Blood vessels in adipose tissue run through sulci
Right and left coronary arteries supply blood to heart wall
only branches off ascending aorta
Ascending aorta
Left coronary artery
(in coronary sulcus)
Right atrium
Circumflex artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)
Right ventricle
Left ventricle
Apex of heart
Descending aorta

33. External anatomy of heart
Fig. 22.5a
External anatomy of heart
Ascending aorta
Circumflex artery supplies left atrium and ventricle
Left coronary artery
(in coronary sulcus)
Right atrium
Circumflex artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)
Right ventricle
Left ventricle
Apex of heart
Descending aorta

34. Fig. 22.9 (a) Coronary arteries
Aortic arch
Pulmonary trunk
Superior vena cava
Left coronary artery
Aortic semilunar valve
Left atrium
Right atrium
Circumflex artery
Branches of left
coronary artery
Right coronary artery
Anterior interventricular
artery
Posterior
interventricular artery
Branches of right
coronary artery
Right marginal artery
Left ventricle
Right ventricle
Right coronary artery branches into
right marginal artery: supplies right border of heart
posterior interventricular artery: supplies posterior left and right ventricles

35. Fig. 22.9 (a) Coronary arteries
Aortic arch
Pulmonary trunk
Superior vena cava
Left coronary artery
Aortic semilunar valve
Left atrium
Right atrium
Circumflex artery
Branches of left
coronary artery
Right coronary artery
Anterior interventricular
artery
Posterior
interventricular artery
Branches of right
coronary artery
Right marginal artery
Left ventricle
Right ventricle
Left coronary artery branches into
circumflex artery: supplies left atrium and left ventricle
anterior interventricular artery: supplies anterior left and right ventricles and interventricular septum
pattern of arterial branching varies among individuals

36. Blood returns from cardiac muscle through cardiac veins
Fig (b) Coronary veins
Polymer cast of coronary vessels
Aortic arch
Superior vena cava
Pulmonary trunk
Left atrium
Right atrium
Coronary sinus
Middle cardiac vein
Small cardiac vein
Great cardiac vein
Right ventricle
Left ventricle
Blood returns from cardiac muscle through cardiac veins
Great cardiac vein runs beside anterior interventricular artery
Middle cardiac vein runs by posterior interventricular artery
Small cardiac vein runs by right marginal artery
All drain into coronary sinus on posterior heart
drains into right atrium

37. Page 664
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Enlarged heart
Abnormal growth of heart can cause swelling in limbs, dizziness, irregular heartbeat, shortness of breath, sudden death
Cardiomegaly in an adult female. Note how the heart shadow encompasses most of the width of the thorax.
Normal heart on x-ray
© ISM/Phototake

38. Fig. 22.7
Contraction of bundles:
Narrows heart
Shortens heart
Cardiac muscle bundles
Spiral arrangement of
cardiac muscle
Cardiac muscle
Fibers arranged in spiral bundles around and between heart chambers
Contractions start at top of atria, move around atria, then start from bottom of ventricle and travel up

39. transverse (T) tubules
Fig
Openings of
transverse (T) tubules
Intercalated disc
Cardiac muscle
Folded
sarcolemma
fibers are striated
intercalated discs have desmosomes and gap junctions
link cells electrically and mechanically
impulses sent immediately form one cell to next
Desmosomes
Intercalated
discs
Gap junctions
Endomysium
Sarcolemma
Cross section of cardiac muscle cells
Nucleus
(b) Intercellular junctions
Mitochondrion

40. Fig
1. Muscle impulse is generated at the sinoatrial node. It spreads throughout the atria and to the atrioventricular node by the internodal pathway.
Sinoatrial node (pacemaker)
Internodal pathway
Atrioventricular node
Atrioventricular bundle
(bundle of His)
Purkinje fibers
Left bundles
Purkinje fibers
Heart is autorhythmic
starts its own beating
Specialized cells that initiate and conduct muscle impulses are collectively the conducting system
Right bundle

41. 2. Atrioventricular node cells delay the
Fig
Sinoatrial node (pacemaker)
Internodal
pathway
Atrioventricular node
Atrioventricular
node
Atrioventricular
bundle
2. Atrioventricular node cells delay the
muscle impulse as it passes to the
atrioventricular bundle.

42. Fig
Sinoatrial node (pacemaker)
Internodal
pathway
Atrioventricular node
Atrioventricular
node
Atrioventricular
bundle
3. The atrioventricular bundle (bundle of His) conducts the muscle impulse into the interventricular septum.
Atrioventricular
bundle
Interventricular
septum

43. Fig
4. Within the interventricular septum, the left and right bundles split from the atrioventricular bundle.
Atrioventricular
bundle
Interventricular
septum
Left and right
bundles

44. Fig
5. The muscle impulse is delivered to Purkinje fibers in each ventricle and distributed throughout the ventricular myocardium.
Atrioventricular
bundle
Interventricular
septum
Left and right
bundles
Purkinje fibers

45. Fig. 22.11 Superior vena cava Right atrium Left atrium
Sinoatrial node (pacemaker)
Internodal
pathway
Internodal pathway
Atrioventricular node
Atrioventricular
node
Atrioventricular bundle
(bundle of His)
Interventricular
septum
Atrioventricular
bundle
Right bundle
Purkinje fibers
Left bundles
Purkinje fibers 1
Muscle impulse is generated at the sinoatrial node. It spreads throughout the atria and
to the atrioventricular node by the internodal pathway. 2
Atrioventricular node cells delay the
muscle impulse as it passes to the
atrioventricular bundle.
Atrioventricular
bundle
Interventricular
septum
Left and right
bundles
Purkinje fibers 3
The atrioventricular bundle (bundle
of His) conducts the muscle impulse
into the interventricular septum. 4
Within the interventricular septum, the
left and right bundles split from the
atrioventricular bundle. 5
The muscle impulse is delivered to Purkinje
fibers in each ventricle and distributed
throughout the ventricular myocardium.

46. Page 669 1 3 2 0.8 second R +1 Millivolts P wave T wave Q S
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
0.8 second R +1 1
P wave 3
T wave
Millivolts Q S 2
QRS complex –1
The events of a single cardiac cycle as recorded on an electrocardiogram.

47. Ventricular systole Contraction of ventricles Semilunar valves open
Fig a
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
(a) Ventricular Systole (Contraction)
Ventricular systole
Aortic arch
Blood flow into
ascending aorta
Ascending
aorta
Pulmonary
trunk
Contraction of ventricles
Semilunar valves open
Blood flows into arteries
Larger of blood pressure measurements
Blood flow into
right atrium
Blood flow into
pulmonary trunk
Right
atrium
Left
atrium
Ventricular contraction pushes
blood against the open AV
valves, causing them to close.
Contracting papillary muscles
and the chordae tendineae
prevent valve flaps from
everting into atria.
Ventricles contract, forcing
semilunar valves to open and
blood to enter the pulmonary
trunk and the ascending aorta.
Atrioventricular valves closed
Semilunar valves open
Right ventricle
Left ventricle
Cusp of
atrioventricular
valve
Cusp of
semilunar
valve
Blood in
ventricle
Posterior
Left AV
valve (closed)
Right AV
valve (closed)
Left ventricle
Right
ventricle
Aortic semilunar
valve (open)
Pulmonary
semilunar
valve (open)
Anterior
Transverse section

48. Ventricular diastole Relaxation of ventricles AV valves open
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Fig b
(b) Ventricular Diastole (Relaxation)
Ventricular diastole
Aortic arch
Blood flow into
right atrium
Blood flow into
left ventricle
Relaxation of ventricles
AV valves open
Blood flows into ventricles from atria
Smaller of blood pressure measurements
Right
atrium
Left
atrium
During ventricular relaxation,
some blood in the ascending
aorta and pulmonary trunk
flows back toward the
ventricles, filling the semilunar
valve cusps and forcing them
to close.
Blood flow into
right ventricle
Ventricles relax and fill with
blood both passively and
then by atrial contraction as
AV valves remain open.
Atrioventricular valves open
Semilunar valves closed
Right ventricle
Left ventricle
Atrium
Cusp of
atrioventricular
valve
Blood
Cusps of
semilunar
valve
Chordae
tendineae
Papillary
muscle
Posterior
Left AV
valve (open)
Right AV
valve (open)
Left ventricle
Right ventricle
Aortic semilunar
valve (closed)
Pulmonary
semilunar
valve (closed)
Anterior
Transverse section

49. Fetal circulation Inferior vena cava flows into right atrium
Fig
Fetal circulation
Inferior vena cava flows into right atrium
Much of the blood bypasses lungs through foramen ovale, opening between right and left atria
Ductus arteriosus takes blood directly from pulmonary trunk to aorta
Some blood flows through pulmonary system and left side of heart, continues normal pathway
Umbilical arteries carry blood to placenta

50. Fetal Cardiovascular Structure Postnatal Structure Ductus arteriosus
Fig
Superior vena cava
Aortic arch
Ductus arteriosus
Pulmonary artery
Pulmonary trunk
Pulmonary veins
Foramen ovale
Lung
Right atrium
Right ventricle
Heart
Liver
Ductus venosus
Inferior vena cava
Descending abdominal aorta
Umbilical vein
Umbilicus (not visible)
Common iliac artery
Urinary bladder
Umbilical arteries
Internal iliac artery
Umbilical cord
Placenta 8 7 1 2 3 4 5 6
Fetal Cardiovascular Structure
Postnatal
Structure
Ductus arteriosus
Ligamentum arteriosum
Ductus venosus
Ligamentum venosum
Foramen ovale
Fossa ovalis
Umbilical arteries
Medial umbilical ligaments
Umbilical vein
Round ligament of liver (ligamentum teres)

51. Other heart structures
Fig. 22.6
Other heart structures
Ligamentum arteriosum
Fossa ovalis is location of former fetal foramen ovale
hole that moved blood between atria, bypassing lungs
Ligamentum arteriosum connects pulmonary trunk to aorta
fibrous structure that forms from fetal ductus arteriosus
Coronary sinus drains blood from coronary veins
Fossa ovalis
Opening for
coronary sinus