Ch 21: Cardiovascular SystemCh 21: Cardiovascular System- The Heart -- The Heart -

Ch 21: Cardiovascular SystemCh 21: Cardiovascular System- The Heart -- The Heart -

Give a detailed description of the superficial 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 how they relate to the heart sounds.

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

Goals

Pulmonary & Systemic CircuitsPulmonary & Systemic CircuitsPulmonary & Systemic CircuitsPulmonary & Systemic Circuits

artery

vein

capillaries

Location of Heart within Location of Heart within Thoracic CavityThoracic Cavity

Location of Heart within Location 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

PericardiumPericardium - - CoveringCoveringPericardiumPericardium - - CoveringCovering1. Fibrous pericardium - tough, collagenous1. Fibrous pericardium - tough, collagenous

2. Serous parietal pericardium (lines fibrous pericardium)2. Serous parietal pericardium (lines fibrous pericardium)

3. Pericardial space with 3. Pericardial space with 10-20 ml of pericardial fluid

4. Serous visceral pericardium adheres to the heart surface4. Serous visceral pericardium adheres to the heart surface

(also known as epicardium)(also known as epicardium)

Structure of Heart WallStructure of Heart WallStructure 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 with endothelia endothelia of of blood vesselsblood vessels

Cardiac MuscleCardiac MuscleCardiac MuscleCardiac Muscle

Striated, aerobic, Striated, aerobic, interwoven, interwoven, autorhythmicautorhythmic

Intercalated discs - Intercalated discs - gap junctions, strong gap junctions, strong desmosomes desmosomes

Functional syncytiumFunctional syncytium

Fig 21.3

Fibrous SkeletonFibrous SkeletonFibrous SkeletonFibrous Skeleton

Internal c.t. network with lots of collagen Internal c.t. network with lots of collagen and elastic fibersand elastic fibers

Encircles bases of great vesselsEncircles bases of great vessels

Encircles bases of valvesEncircles bases of valves

functions:functions:Isolate atria from ventricles elctricallyIsolate atria from ventricles elctrically

Reinforce myocardium itselfReinforce myocardium itself

Surface Anatomy of Heart Surface Anatomy of Heart Surface Anatomy of Heart Surface 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 heart entering & leaving the heart

Fig 21.5

Sectional (Internal) Heart Sectional (Internal) Heart AnatomyAnatomy

Sectional (Internal) Heart Sectional (Internal) Heart AnatomyAnatomy

Atria & ventriclesAtria & ventricles

Interatrial & interventricular septaeInteratrial & interventricular septae

Valves (fibrous tissue)Valves (fibrous tissue)

Pectinate muscles (auricles & ant. atria)Pectinate muscles (auricles & ant. atria)

Trabeculae carneae (ventricles)Trabeculae carneae (ventricles)

Chordae tendinae & papillary musclesChordae tendinae & papillary musclesFig 21.6

Left vs. Right VentricleLeft vs. Right VentricleLeft vs. Right VentricleLeft vs. Right Ventricle

Left: high pressure Left: high pressure pump - Right: low pump - Right: low pressure pump pressure pump right chamber is right chamber is thinner walled than thinner walled than leftleft

Ventricles separated Ventricles separated by interventricular by interventricular septumseptum

Structure and Function of ValvesStructure and Function of Valves

= Mitral valve

4 sets of valves

Prevent backflow of blood

Close passively under blood pressure

Heart sounds produced by valve closure

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

Support for AV valves: Support for AV valves:

valves are restrained by chordae tendinae which are in turn attached to papillary muscles (prevention of backflow!)

Mitral Valve ProlapseMitral Valve ProlapseMitral Valve ProlapseMitral Valve Prolapse Most common cardiac variation (5-10% of population)Most common cardiac variation (5-10% of population)

Mitral valve cusps do not Mitral valve cusps do not close close properlyproperly

Regurgitation during left Regurgitation during left ventricular ventricular systolesystole

Not life threatening; Not life threatening; may be may be

lifestyle threateninglifestyle threatening

How can you How can you diagnosediagnose??

Blood flow pattern through the heartBlood flow pattern through the heartBlood flow pattern through the heartBlood flow pattern through the heart

1.1. Blood enters right atriumBlood enters right atrium2.2. Passes tricuspid valve into right ventriclePasses tricuspid valve into right ventricle3.3. Leaves by passing pulmonary semilunar valves into Leaves by passing pulmonary semilunar valves into

pulmonary trunk and to the lungs to be oxygenatedpulmonary trunk and to the lungs to be oxygenated4.4. Returns from the lung by way of pulmonary veins into the Returns from the lung by way of pulmonary veins into the

left atriumleft atrium5.5. From left atrium past bicuspid valve into left ventricleFrom left atrium past bicuspid valve into left ventricle6.6. Leaves left ventricle past aortic semilunar valves into Leaves left ventricle past aortic semilunar valves into

aortaaorta7.7. Distributed to rest of the bodyDistributed to rest of the body

Actual physical contraction pattern of the myocardium as determined by the conduction.

A.Contraction is systole

B. Relaxation is diastole

The two atria are in systole and diastole together as are the two ventricles.

Cardiac Cycle

Auscultation of Heart Sounds:

1st HS: at beginning of ventricular contraction, due to?2nd HS: at beginning of ventricular diastole, due to?

Coronary CirculationCoronary CirculationCoronary CirculationCoronary CirculationCoronary arteries: first branches off the ascending aorta.

coronary veins coronary sinus right atrium (inferior to opening of inferior vena cava)

posterior view

Coronary Artery Disease (CAD)

PET scan

the brighter the color the greater the blood flow through tissue

due to ?consequences ?

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 → nonfunctional area = Ischemic tissue degenerates → nonfunctional area =

infarctinfarct Predisposing factors?Predisposing factors?

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 and Specialized muscle cells (autorhythmic cells) conduct APs to time and synchronize the action of the chambers synchronize the action of the chambers

SASA nodenode -pacemaker, spontaneously depolarizes most rapidly and initiate -pacemaker, spontaneously depolarizes most rapidly and initiate heart beat, positioned on back wall of right atrium , transmits action heart beat, positioned on back wall of right atrium , transmits action potential topotential 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 septum where it divides into twowhere it divides into two

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

Purkinje fibersPurkinje fibers reflect up external walls of ventricles and stimulate reflect up external walls of ventricles and stimulate contraction 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