Lecture 23

Front 1

1. Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta.

As mentioned above.

Back 1

A) Umbilical vein
B) Liver
C) Hepatic vv. and ductus venosus
D) Inferior vena cava
E) Right atrium - Foramen ovale - Left atrium
F) Left ventricle
G) Aorta
H) Superior vena cava
I) Right atrium - Right ventricle - Pulmonary a. - Ductus arteriosus
J) Aorta
K) Umbilical aa.
L) Placenta

Front 2

1. Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta.

Umbilical vein

Back 2

»Is named "vein" relative to the circulatory system of the fetus, not the mother.
»After birth, this becomes ligamentum teres hepatis.

Front 3

(Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta)

Liver

Back 3

»Receives about half of the blood from the umbilical v.
»The other half passes directly to inferior vena cava via ductus venosus which becomes the ligamentum venosum after birth.

Front 4

(Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta)

Aorta

Back 4

»From which, most blood passes to heart, head, and upper limbs.

Front 5

(Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta)

Right atrium --> Right ventricle --> Pulmonary a. --> Ductus arteriosus

Back 5

»Only a small amount of blood passes from pulmonary a. into the inactive lungs.

»Note that the ductus arteriosus connects at the "distal" part of the aortic arch, so fetal blood that has already served the head and upper limbs will tend to continue into the descending aorta.
»After birth, the ductus arteriosus becomes the ligamentum arteriosum.

Front 6

(Describe the fetal circulation by listing in sequence, the major structures through which blood passes as it passes from placenta to fetus and back to placenta)

Umbilical aa.

Back 6

»Branches of the interal iliac aa.

»(Some blood continues into lower limbs and abdominal/pelvic viscera via branches from the aorta.)

»After birth, the umbilical aa. form ridges (medial umbilical ligaments).

Front 7

2. Describe the pericardium and the surface anatomy of the heart.

Pericardium

Back 7

»Double walled sac that encloses the heart and great vessels:

1) The parietal pericardium consists of an outer fibrous layer and an inner serous layer.

2) The visceral pericardium (epicardium) is serous only.

Front 8

(Describe the pericardium and the surface anatomy of the heart)

Heart

Back 8

Composed of...
1) Four chambers: (i) Two atria and (ii) Two ventricles.
2) Apex
3) Three surfaces: (i) Anterior, (ii) Diaphragmatic, and (iii) posterior E.g. the "base."
4) Four borders: (i) Right, (ii) Inferior, (iii) Left, and (iv) Superior border.

Front 9

(Describe the pericardium and the surface anatomy of the heart)

Borders

Back 9

»The heart is composed of four borders:

(i) Right border - vertical along costal cartilages 3 to 6.
(ii) Inferior border - horizontally from inferior end of right border, behind the xiphisternal junction to the apex.
(iii) Left border - from apex upward and medially to the articulation between the 2nd costal cartilage and the sternum.
(iv) Superior border - behind the sternal angle.

Note: These borders apply to the supine patient; the heart is slightly lower in the erect position.

Front 10

3. Describe each of the four chambers of the heart.

Right atrium

Back 10

»The interior consists of a smooth part marked by fossa ovalis (former foramen ovale)
»It's associated with the openings of the superior and inferior vena cavae, and the coronary sinus.

»The anterior part is rough-walled, containing musculi pectinati and crista terminalis (a landmark for the "SA node").

»The right atrioventricular (tricuspid) orifice is closely associated with the anterior wall.

Front 11

(Describe the pericardium and the surface anatomy of the heart)

Right ventricle

Back 11

»Contains papillary mm. (irregular muscle bundles) which are attached to the cusps of the tricuspid valve (right atrioventricular valve) via the chordae tendinae.
»The papillary mm. stabilize the tricuspid valve to help prevent regurgitation of blood back into the right atrium during systole.

»During contraction, blood leaves the right ventricle via the valve of the pulmonary trunk.

Front 12

(Describe the pericardium and the surface anatomy of the heart)

Left atrium

Back 12

»This chamber forms the posterior aspect (base) of the heart.

»The four pulmonary vv. empty into it, bringing oxygenated blood from the lungs.

Front 13

(Describe the pericardium and the surface anatomy of the heart)

Left ventricle

Back 13

»Thick walled chamber that's responsible for pumping blood into the systemic circulation.

»It contains trabeculae carnae (like right ventricle), and anterior and posterior papillary mm. which attach to the left atrioventricular (mitral) valve via chordae tendinae.

Front 14

(Describe the pericardium and the surface anatomy of the heart)

Mitral valve

Back 14

»Left atrioventricular valve
»Two-cusped, i.e. bicuspid, and is shaped like a the bishop's miter (hat) for which it was named.

Front 15

(Describe the pericardium and the surface anatomy of the heart)

What marks entrance to the Left ventricle and what gaurds the exit?

Back 15

»The mitral valve marks the entrance to the chamber.

»The aortic valve guards the exit, and closes to prevent regurgitation from the distended aortic arch back into the ventricle during diastole.

Front 16

(Describe the pericardium and the surface anatomy of the heart)

Mitral stenosis

Back 16

»Pathologic narrowing of the left atrioventricular orifice, which
»Leads to increased pressure in the left atrium and "back-pressure" that may cause pulmonary congestion.

Front 17

4. Describe the blood supply to the heart.

Coronary arteries

Back 17

»Coronary aa. arise from the root of the aorta, at the right and left aortic sinuses.

Front 18

(Describe the blood supply to the heart)

Right coronary a.

Back 18

»Travels in the coronary sulcus.
»Supplies much of the right atrium and right ventricle.
»Anastomoses with the circumflex branch of the left coronary a. at the posterior aspect of the heart.

Front 19

(Describe the blood supply to the heart)

Left coronary a.

Back 19

»Divides into a (i)circumflex branch that passes over the left margin of the heart to reach the posterior aspect, and an (ii)anterior descending branch which passes downward along the interventricular groove.

»The left atrium and left ventricle are largely supplied by the left coronary a.

Front 20

(Describe the blood supply to the heart)

Ischemia

Back 20

»Disruption of blood flow to the heart results in ischemia, and frequently, death (necrosis) of that part of the heart that is without adequate circulation.

Front 21

(Describe the blood supply to the heart)

Infarct

Back 21

»An area of myocardium that has undergone necrosis is an infarct.

Front 22

5. Describe the venous system of the heart.

Name the vv. of the heart and their location.

Back 22

1) Great cardiac v. - runs with the left anterior descending a. (LAD), and continues alongside the circumflex branch of the left coronary a.

2) Middle cardiac v. - Runs with the posterior interventricular a.

3) Small cardiac v. - runs with the marginal branch of the right coronary a. at the anterior aspect of heart, and continues posteriorly alongside the right coronary a.

Front 23

(Describe the venous system of the heart)

Where does blood from the cardiac veins ultimately empty into?

Back 23

»Great cardiac v., middle cardiac v., and small cardiac v. ultimately empty into the coronary sinus, which empties into the right atrium.

Front 24

6. Describe the major components of the conducting system of the heart.

SA node

Back 24

»Sinuatrial node - located at the superior end of the crista terminalis in the right atrium.

»Often called the pacemaker of the heart.

»Normal resting pace of 60-70 beats/min can be increased by sympathetic stimulation.
»It can be decreased or stopped by vagal stimulation.

Front 25

(Describe the major components of the conducting system of the heart)

AV node

Back 25

»Atrioventricular node - located in the posteroinferior part of the interatrial septum.

»Impulses from both atria converge on the AV node, which distribute impulses to the atrioventricular bundle.

Front 26

(Describe the major components of the conducting system of the heart)

Atrioventricular bundle

Back 26

»Located in the interventricular septum.
»This bundle divides into left and right bundle branches by which impulses travel rapidly to the apex thereby allowing the ventricles to contract from the apex upward, effectively squeezing the blood out.

Front 27

(Describe the major components of the conducting system of the heart)

What also receives the rapid impulses of the atrioventricular bundle? For what purpose?

Back 27

»The papillary mm. also receive these rapid impulses.

»So they can prepare early to pull on the atrioventricular valve cusps, stabilizing them and preventing their eversion during systole.

Front 28

7. Describe aspects of cardiac auscultation.

What is the best location to hear each valve (pulmonary, aortic, mitral, and tricuspid valves)?

Back 28

»The best locations to hear each valve is the so-called "points of maximum intensity" (PMIs)
»These points do not simply correspond to the closest spots on the surface of the chest.

Front 29

(Describe aspects of cardiac auscultation)

Mitral valve auscultation

Back 29

»Auscultated superficial to the apex of the heart, at the left 5th intercostal space.

Front 30

(Describe aspects of cardiac auscultation)

Tricuspid valve auscultation

Back 30

»Auscultated over the left half of the inferior end of the body of the sternum.

Front 31

(Describe aspects of cardiac auscultation)

Aortic valve auscultation

Back 31

»Auscultated at the right edge of the sternum at the level of the 2nd intercostal space (just inferior to the level of the sternal angle).

Front 32

(Describe aspects of cardiac auscultation)

Pulmonary valve

Back 32

»Auscultated at the left edge of the sternum of the sternum at the level of the 2nd intercostal space.

Front 33

(Describe aspects of cardiac auscultation)

"Lub"

Back 33

»The first heart sound is made when the atrioventricular valves close, i.e. early in systole.

Front 34

(Describe aspects of cardiac auscultation)

"Dub"

Back 34

»Second heart sound is made when the aortic and pulmonary valves close, i.e. at the end of systole, when the pressure is high in the aortic arch and pulmonary trunk.

Front 35

(Describe aspects of cardiac auscultation)

Deficiencies

Back 35

»Deficiencies in valve function cause characteristic changes in the heart sounds (murmers).

Front 36

(Describe aspects of cardiac auscultation)

"Luff-dub"

Back 36

»Head at the apex, suggests a mitral valve problem.

Front 37

(Describe aspects of cardiac auscultation)

"Lub-duff"

Back 37

»Heard at the right edge of the sternum at the level of the 2nd intercostal space, suggests a problem at the aortic valve.

Front 38

7. Review the anatomy of the great vessels and briefly describe the azygos system of veins.

Back 38

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