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Ch 21: Cardiovascular SystemCh 21: Cardiovascular System

-- The HeartThe Heart --

Ch 21: Cardiovascular SystemCh 21: Cardiovascular System

-- The HeartThe Heart --

Give a detailed description of thesuperficial and internal anatomy of the

heart, including the pericardium, the

myocardium, and the cardiac muscle.

Explain the functioning of the valves of the heart and howthey relate to the heart sounds.

Discuss the conductive pathway of the heart, and relatethat to clinical uses of the ECG.

Goals

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Pulmonary & Systemic CircuitsPulmonary & Systemic Circuits

Pulmonary & Systemic CircuitsPulmonary & Systemic Circuits

artery

vein

capillaries

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Location of Heart withinLocation of Heart within

Thoracic CavityThoracic Cavity

Location of Heart withinLocation of Heart within

Thoracic CavityThoracic Cavity

Inside thoracic cavity

In center of chest deep to

sternum, apex tipped toward the

left; base superior 

Inside mediastinum

In pericardial space

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PericardiumPericardium -- Covering Covering 

PericardiumPericardium -- Covering Covering 

1. Fibrous pericardium 1. Fibrous pericardium -- tough, collagenoustough, collagenous2. Serous parietal pericardium (lines f ibrous pericardium)2. Serous parietal pericardium (lines f ibrous pericardium)

3. Pericardial space with 3. Pericardial space with 10-20 ml of pericardial f luid

4. Serous visceral pericardium adheres to the heart surf ace4. Serous visceral pericardium adheres to the heart surf ace

(also k nown as epicardium)(also k nown as epicardium)

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Structure of Heart WallStructure of Heart Wall

Structure of Heart WallStructure of Heart Wall

EpicardiumEpicardium = visceral Pericardium (serosa)= visceral Pericardium (serosa)

MyocardiumMyocardium: muscle tissue + c.t. + blood vessels + ?: muscle tissue + c.t. + blood vessels + ?

EndocardiumEndocardium: simple squamous epithelium continuous: simple squamous epithelium continuous

with endotheliawith endotheliaof blood vesselsof blood vessels

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Fibrous SkeletonFibrous SkeletonFibrous SkeletonFibrous Skeleton

Internal c.t. network with lots of collagen Internal c.t. network with lots of collagen 

and elastic f ibersand elastic f ibersEncircles bases of great vesselsEncircles bases of great vessels

Encircles bases of valvesEncircles bases of valves

 functions: functions:Isolate atria f rom ventricles elctricallyIsolate atria f rom ventricles elctrically

R einf orce myocardium itself R einf orce myocardium itself 

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Surface Anatomy of HeartSurface Anatomy of HeartSurface Anatomy of HeartSurface Anatomy of Heart

AuricleAuricle of atria (expandable)of atria (expandable)

Coronary sulcusCoronary sulcus (between atria &(between atria &

ventricles)ventricles)

Ant. & post.Ant. & post. interventricular sulcusinterventricular sulcus

BaseBase (3(3rdrd costal cartilage)costal cartilage) vs.vs. apexapex (5(5thth intercostal intercostal space)space)

VesselsVessels entering & leaving the heartentering & leaving the heart

 F ig 21.5

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Sectional (Internal) HeartSectional (Internal) Heart

AnatomyAnatomy

Sectional (Internal) HeartSectional (Internal) Heart

AnatomyAnatomy

Atria & ventriclesAtria & ventricles

Interatrial & interventricular septaeInteratrial & interventricular septae

Valves (f ibrous tissue)Valves (f ibrous tissue)

Pectinate muscles (auricles & ant. atria)Pectinate muscles (auricles & ant. atria) Trabeculae carneae (ventricles)Trabeculae carneae (ventricles)

Chordae tendinae & papillary musclesChordae tendinae & papillary muscles

 F ig 21.6 

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Left vs. Right VentricleLeft vs. Right VentricleLeft vs. Right VentricleLeft vs. Right VentricleLeft: high pressureLeft: high pressure

 pump pump -- Right: lowRight: low

 pressure pump pressure pumpright chamber isright chamber is

thinner walled thanthinner walled than

leftleft

Ventricles separatedVentricles separated

 by interventricular  by interventricular 

septumseptum

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Structure and Function of ValvesStructure and Function of Valves

= Mitral valve

4 sets of valves

Prevent backf low of 

blood

Close passively under blood pressure

Heart sounds produced by valve closure

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 picture taken from R ventricle, looking toward R atrium (  see f  ig 21.6)

Support f or AV valves: Support f or AV valves: 

valves are restrained by

chordae tendinae which are

in turn attached to papillary

muscles (prevention of 

 backflow!)

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Mitral Valve ProlapseMitral Valve ProlapseMitral Valve ProlapseMitral Valve Prolapse

Most common cardiac variation (5Most common cardiac variation (5--10% of 10% of 

population)population)

Mitral valve cusps do notMitral valve cusps do not

close properlyclose properly

R egurgitation during leftR egurgitation during left

ventricular systoleventricular systole

Not lif e threatening; Not lif e threatening; 

may be may be lif estyle threateninglif estyle threatening

 H ow can you H ow can you diagnosediagnose??

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Blood f low pattern through the heartBlood f low pattern through the heartBlood f low pattern through the heartBlood f low pattern through the heart

1.1. Blood enters right atriumBlood enters right atrium

2.2. Passes tricuspid valve into right ventriclePasses tricuspid valve into right ventricle

3.3. Leaves by passing pulmonary semilunar valves intoLeaves by passing pulmonary semilunar valves into pulmonary trunk and to the lungs to be oxygenated pulmonary trunk and to the lungs to be oxygenated

4.4. Returns from the lung by way of pulmonary veins into theReturns from the lung by way of pulmonary veins into theleft atriumleft atrium

5.5. From left atrium past bicuspid valve into left ventricleFrom left atrium past bicuspid valve into left ventricle

6.6. Leaves left ventricle past aortic semilunar valves intoLeaves left ventricle past aortic semilunar valves intoaortaaorta

7.7. Distributed to rest of the bodyDistributed to rest of the body

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Actual physical

contraction pattern of themyocardium as

determined by the

conduction.

A. Contraction is systole

B. Relaxation is diastole

The two atria are insystole and diastole

together as are the two

ventricles.

Cardiac Cycle

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Auscultation of Heart Sounds:

1st HS: at beginning of ventricular contraction, due to?

2nd HS: at beginning of ventricular diastole, due to?

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Coronary CirculationCoronary CirculationCoronary CirculationCoronary Circulation

Coronary arteries: first branches off the ascending aorta.

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coronary veins coronary sinus right atrium

(inferior to opening

of inferior vena cava)

 posterior view

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Coronary Artery Disease (CAD)

PET scan

the brighter the color the greater the blood flow through tissue

d ue to ?

consequences ?

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Myocardial Infarction (MI)Myocardial Infarction (MI)Myocardial Infarction (MI)Myocardial Infarction (MI)

~ 1.3 Mio MIs / year in US~ 1.3 Mio MIs / year in US

Most commonly due to severe CAD (coronary Most commonly due to severe CAD (coronary 

thrombosis)thrombosis)

Ischemic tissue degenerates nonf unctional area = Ischemic tissue degenerates nonf unctional area = 

inf arctinf arct

Predisposing f actors?Predisposing f actors?

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Conducting System of the HeartConducting System of the HeartConducting System of the HeartConducting System of the Heart

Specialized muscle cells (autorhythmic cells) conduct APs to time andSpecialized muscle cells (autorhythmic cells) conduct APs to time andsynchronize the action of the chamberssynchronize the action of the chambers

SA

SA

nodenode --pacemaker, spontaneously depolarizes most rapidly and initiate pacemaker, spontaneously depolarizes most rapidly and initiateheart beat, positioned on back wall of right atrium , transmits actionheart beat, positioned on back wall of right atrium , transmits action potential to potential to

AVAV nodenode -- (where the four chambers meet).(where the four chambers meet).

AVAV bundlebundle (bundle of His) transmits down top of interventricular septum(bundle of His) transmits down top of interventricular septumwhere it divides into twowhere it divides into two

Bundle branchesBundle branches, one of which supplies each ventricle where they branch, one of which supplies each ventricle where they branchintointo

Purk in je f ibersPurk in je f ibers reflect up external walls of ventricles and stimulatereflect up external walls of ventricles and stimulatecontraction of cardiac muscle cells as a unit.contraction of cardiac muscle cells as a unit.

Purkinje fibers extend into papillary muscles as wellPurkinje fibers extend into papillary muscles as well