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
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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
Wall between atria is interatrial septum
Wall between ventricles is interventricular septum
Interatrial
septum
Interventricular
septum

23. 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

24. 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

25. 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

26. 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

27. 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

28. External anatomy of heart
Fig. 22.5a
External anatomy of heart
Coronary arteries supply blood to heart muscle
Coronary veins return blood from heart tissue back to right atrium
Blood enters atrium through coronary sinus
Left coronary artery
(in coronary sulcus)
Circumflex artery
(in coronary sulcus)
Right coronary artery
(in coronary sulcus)

29. 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

30. 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
Right bundle
Heart is autorhythmic
starts its own beating
Specialized cells that initiate and conduct muscle impulses are collectively the conducting system

31. 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 (Bundle of His).

32. 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

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

34. 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

35. 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.

36. R P wave T wave Q S QRS complex 1 2 3 0.8 second +1 Millivolts –11 2 3
T wave
P wave
QRS complex
The events of a single cardiac cycle as recorded on an electrocardiogram.

37. 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

38. 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

39. Fetal Circulation Where does oxygen come from?
Where does blood get filtered?
Where do nutrients come from?
Different needs of fetal circulation:
Transport blood to and from placenta
Return blood to fetal circulatory system
Bypass developing liver and lungs

40. Umbilical Cord
Deoxygenated blood travels to placenta through umbilical arteries
Oxygenated blood arrives from placenta through umbilical vein
Maternal and fetal blood do not mix

41. Bypassing the Liver Umbilical vein splits near liver
~2/3 blood travels to developing liver through hepatic portal vein
Ductus venosus carries ~1/3 of blood to inferior vena cava

42. Bypassing the Lungs Blood flows into right atrium
Foramen ovale is hole between right and left atria
Most blood flows through foramen ovale
A small amount flows into right ventricle and through pulmonary trunk

43. Bypassing the Lungs
Ductus arteriosus is connection between pulmonary artery and aorta
Most blood in pulmonary artery goes through ductus arteriosus, bypassing pulmonary circuit

44. 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)