Figure 18.1a

Copyright © 2010 Pearson Education, Inc. Figure 18.1a

Point ofmaximalintensity(PMI)

Diaphragm

(a)

Sternum2nd ribMidsternal line

Copyright © 2010 Pearson Education, Inc. Figure 18.1c

(c)

Superiorvena cava

Left lung

AortaParietalpleura (cut)

Pericardium(cut)

Pulmonarytrunk

DiaphragmApex ofheart

Copyright © 2010 Pearson Education, Inc. Figure 18.2

Fibrous pericardiumParietal layer ofserous pericardiumPericardial cavityEpicardium(visceral layerof serouspericardium)MyocardiumEndocardium

Pulmonarytrunk

Heart chamber

Heartwall

PericardiumMyocardium

Copyright © 2010 Pearson Education, Inc. Figure 18.4b

(b) Anterior view

Brachiocephalic trunk

Superior vena cava

Right pulmonaryarteryAscending aortaPulmonary trunk

Right pulmonaryveins

Right atriumRight coronary artery(in coronary sulcus)Anterior cardiac veinRight ventricle

Right marginal artery

Small cardiac vein

Inferior vena cava

Left common carotidarteryLeft subclavian artery

Ligamentum arteriosumLeft pulmonary artery

Left pulmonary veins

Circumflex artery

Left coronary artery(in coronary sulcus)

Left ventricle

Great cardiac veinAnterior interventricularartery (in anteriorinterventricular sulcus)Apex

Aortic arch

Auricle ofleft atrium


Atria: The Receiving Chambers

•Walls are ridged by pectinate muscles

• Vessels entering right atrium• Superior vena cava

• Inferior vena cava

• Coronary sinus

• Vessels entering left atrium• Right and left pulmonary veins


Ventricles: The Discharging Chambers

•Walls are ridged by trabeculae carneae

• Papillary muscles project into the ventricular cavities

• Vessel leaving the right ventricle• Pulmonary trunk

• Vessel leaving the left ventricle• Aorta

Copyright © 2010 Pearson Education, Inc. Figure 18.4e

AortaLeft pulmonaryarteryLeft atriumLeft pulmonaryveins

Mitral (bicuspid)valve

Aortic valvePulmonary valveLeft ventricle

Papillary muscleInterventricularseptumEpicardiumMyocardiumEndocardium

(e) Frontal section

Superior vena cavaRight pulmonaryarteryPulmonary trunkRight atriumRight pulmonaryveinsFossa ovalisPectinate musclesTricuspid valveRight ventricle

Chordae tendineaeTrabeculae carneaeInferior vena cava


Pathway of Blood Through the Heart

• The heart is two side-by-side pumps• Right side is the pump for the pulmonary

circuit

• Vessels that carry blood to and from the lungs

• Left side is the pump for the systemic circuit

• Vessels that carry the blood to and from all body tissues


Oxygen-rich,CO2-poor bloodOxygen-poor,CO2-rich blood

Capillary bedsof lungs wheregas exchangeoccurs

Capillary beds of allbody tissues wheregas exchange occurs

Pulmonary veinsPulmonary arteries

PulmonaryCircuit

SystemicCircuit

Aorta and branches

Left atrium

HeartLeft ventricleRight atrium

Right ventricle

Venae cavae


Pathway of Blood Through the Heart

• Equal volumes of blood are pumped to the pulmonary and systemic circuits

• Pulmonary circuit is a short, low-pressure circulation

• Systemic circuit blood encounters much resistance in the long pathways


Rightventricle

Leftventricle

Interventricularseptum


Coronary Circulation

• The blood supply to heart muscle


Rightventricle

Rightcoronaryartery

Rightatrium

Rightmarginalartery Posterior

interventricularartery

Anteriorinterventricularartery

Circumflexartery

Leftcoronaryartery

Aorta

Anastomosis(junction ofvessels)

Leftventricle

Superiorvena cava

(a) The major coronary arteries

Left atrium

Pulmonarytrunk


Superiorvena cava

Anteriorcardiacveins

Small cardiac veinMiddle cardiac vein

GreatcardiacveinCoronarysinus

(b) The major cardiac veins

Copyright © 2010 Pearson Education, Inc. Figure 18.4d

(d) Posterior surface view

AortaLeft pulmonaryarteryLeft pulmonaryveinsAuricle of leftatriumLeft atriumGreat cardiacveinPosterior veinof left ventricleLeft ventricle

Apex

Superior vena cavaRight pulmonary arteryRight pulmonary veins

Right atrium

Inferior vena cava

Right coronary artery(in coronary sulcus)

Coronary sinus

Posteriorinterventricularartery (in posteriorinterventricular sulcus)Middle cardiac veinRight ventricle


Homeostatic Imbalances

• Angina pectoris• Thoracic pain caused by deficiency in blood

delivery to the myocardium

• Cells are weakened

• Myocardial infarction (heart attack)• Prolonged coronary blockage

• Cell die & are repaired with scar tissue


Heart Valves

•What purpose do valves serve?

•Where are they located?

•What would you call them?


Pulmonary valveAortic valveArea of cutaway

Mitral valveTricuspid valve

Myocardium

Tricuspid(right atrioventricular)valveMitral(left atrioventricular)valveAorticvalve

Pulmonaryvalve

(b)

Copyright © 2010 Pearson Education, Inc. Figure 18.8c

Pulmonaryvalve

AorticvalveArea ofcutawayMitralvalve

Tricuspidvalve

Chordae tendineaeattached to tricuspid valve flap

Papillarymuscle

(c)

Copyright © 2010 Pearson Education, Inc. Figure 18.8d

PulmonaryvalveAortic valveArea of cutawayMitral valveTricuspidvalve

Mitral valveChordaetendineae

Interventricularseptum

Myocardiumof left ventricle

Opening of inferiorvena cavaTricuspid valve

Papillarymuscles

Myocardiumof rightventricle

(d)


1 Blood returning to theheart fills atria, puttingpressure againstatrioventricular valves;atrioventricular valves areforced open.

1 Ventricles contract, forcingblood against atrioventricularvalve cusps.

2 As ventricles fill,atrioventricular valve flapshang limply into ventricles.

2 Atrioventricular valvesclose.

3 Atria contract, forcingadditional blood into ventricles.

3 Papillary musclescontract and chordaetendineae tighten,preventing valve flapsfrom everting into atria.

(a) AV valves open; atrial pressure greater than ventricular pressure

(b) AV valves closed; atrial pressure less than ventricular pressure

Direction ofblood flowAtrium

Ventricle

Cusp ofatrioventricularvalve (open)

Chordaetendineae

Papillarymuscle

Atrium

Blood inventricle

Cusps ofatrioventricularvalve (closed)


As ventriclescontract andintraventricularpressure rises,blood is pushed upagainst semilunarvalves, forcing themopen.

As ventricles relaxand intraventricularpressure falls, bloodflows back fromarteries, filling thecusps of semilunarvalves and forcingthem to close.

(a) Semilunar valves open

(b) Semilunar valves closed

AortaPulmonarytrunk


Nucleus

DesmosomesGap junctions

Intercalated discs Cardiac muscle cell

(a)


(a) Anatomy of the intrinsic conduction system showing the sequence of electrical excitation

Internodal pathway

Superior vena cavaRight atrium

Left atrium

Purkinje fibers

Inter-ventricularseptum

1 The sinoatrial (SA) node (pacemaker)generates impulses.

2 The impulsespause (0.1 s) at theatrioventricular(AV) node. The atrioventricular(AV) bundleconnects the atriato the ventricles.4 The bundle branches conduct the impulses through the interventricular septum.

3

The Purkinje fibersdepolarize the contractilecells of both ventricles.

5



• Defects in conduction system may result in

1. Arrhythmias: irregular heart rhythms

2. Uncoordinated atrial and ventricular contractions

3. Fibrillation: rapid, irregular contractions; useless for pumping blood



• Defective SA node may result in• Ectopic focus: abnormal pacemaker takes over

• If AV node takes over, there will be a junctional rhythm (40–60 bpm)

• Defective AV node may result in• Partial or total heart block

• Few or no impulses from SA node reach the ventricles


Thoracic spinal cord

The vagus nerve (parasympathetic) decreases heart rate.

Cardioinhibitory center

Cardio-acceleratorycenter

Sympathetic cardiacnerves increase heart rateand force of contraction.

Medulla oblongata

Sympathetic trunk ganglion

Dorsal motor nucleus of vagus

Sympathetic trunk

AV nodeSA node

Parasympathetic fibersSympathetic fibersInterneurons


Electrocardiography

• Electrocardiogram (ECG or EKG): a composite of all contractile cells

• Three waves

1. P wave: depolarization of SA node

2. QRS complex: ventricular depolarization

3. T wave: ventricular repolarization


Sinoatrialnode

Atrioventricularnode

Atrialdepolarization

QRS complex

Ventriculardepolarization

Ventricularrepolarization

P-QInterval

S-TSegment

Q-TInterval


Atrial depolarization, initiatedby the SA node, causes theP wave.

P

R

T

QS

SA node

AV node

With atrial depolarizationcomplete, the impulse isdelayed at the AV node.

Ventricular depolarizationbegins at apex, causing theQRS complex. Atrialrepolarization occurs.

P

R

T

QS

P

R

T

QS

Ventricular depolarizationis complete.

Ventricular repolarizationbegins at apex, causing theT wave.

Ventricular repolarizationis complete.

P

R

T

QS

P

R

T

QS

P

R

T

QS

Depolarization Repolarization

1

2

3

4

5

6

Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 1

Atrial depolarization, initiated bythe SA node, causes the P wave.

P

R

T

QS

SA node DepolarizationRepolarization

1



P

R

T

QS

SA node

AV node

With atrial depolarization complete,the impulse is delayed at the AV node.

P

R

T

QS

DepolarizationRepolarization

1

2



P

R

T

QS

SA node

AV node

With atrial depolarization complete,the impulse is delayed at the AV node.

Ventricular depolarization beginsat apex, causing the QRS complex.Atrial repolarization occurs.

P

R

T

QS

P

R

T

QS


1

2

3


Ventricular depolarization iscomplete.

P

R

T

QS


4



Ventricular repolarization beginsat apex, causing the T wave.

P

R

T

QS

P

R

T

QS


4

5



Ventricular repolarization beginsat apex, causing the T wave.

Ventricular repolarization iscomplete.

P

R

T

QS

P

R

T

QS

P

R

T

QS


4

5

6


Atrial depolarization, initiatedby the SA node, causes theP wave.

P

R

T

QS

SA node

AV node

With atrial depolarizationcomplete, the impulse isdelayed at the AV node.

Ventricular depolarizationbegins at apex, causing theQRS complex. Atrialrepolarization occurs.

P

R

T

QS

P

R

T

QS

Ventricular depolarizationis complete.

Ventricular repolarizationbegins at apex, causing theT wave.

Ventricular repolarizationis complete.

P

R

T

QS

P

R

T

QS

P

R

T

QS

Depolarization Repolarization

1

2

3

4

5

6


(a) Normal sinus rhythm.

(c) Second-degree heart block. Some P waves are not conducted through the AV node; hence more P than QRS waves are seen. In this tracing, the ratio of P waves to QRS waves is mostly 2:1.

(d) Ventricular fibrillation. These chaotic, grossly irregular ECG deflections are seen in acute heart attack and electrical shock.

(b) Junctional rhythm. The SA node is nonfunctional, P waves are absent, and heart is paced by the AV node at 40 - 60 beats/min.


Heart Sounds

• Two sounds (lub-dup) associated with closing of heart valves• First sound occurs as AV valves close and

signifies beginning of systole

• Second sound occurs when SL valves close at the beginning of ventricular diastole

• Heart murmurs: abnormal heart sounds most often indicative of valve problems


Tricuspid valve sounds typically heard in right sternal margin of 5th intercostal space

Aortic valve sounds heard in 2nd intercostal space atright sternal margin

Pulmonary valvesounds heard in 2ndintercostal space at leftsternal margin

Mitral valve soundsheard over heart apex(in 5th intercostal space)in line with middle ofclavicle


Mechanical Events: The Cardiac Cycle

• Cardiac cycle: all events associated with blood flow through the heart during one complete heartbeat• Systole—contraction

• Diastole—relaxation


Phases of the Cardiac Cycle

1. Ventricular filling—takes place in diastole• AV valves are open • 80% of blood passively flows into ventricles• Atrial systole occurs, delivering the remaining

20%


Phases of the Cardiac Cycle

2. Ventricular systole• Atria relax and ventricles begin to contract • Rising ventricular pressure closes AV valves• All valves are closed• In ejection phase, ventricular pressure exceeds

pressure in the large arteries, forcing the SL valves open


1 2a 2b 3

Atrioventricular valvesAortic and pulmonary valves

Open OpenClosed

Closed ClosedOpenPhase

ESV

Left atriumRight atriumLeft ventricleRight ventricle

Ventricularfilling

Atrialcontraction

Ventricular filling(mid-to-late diastole)

Ventricular systole(atria in diastole)

Isovolumetriccontraction phase

Ventricularejection phase

Early diastole

Isovolumetricrelaxation

Ventricularfilling

11 2a 2b 3

Electrocardiogram

Left heart

P

1st 2nd

QRSP

Heart sounds

Atrial systole

Dicrotic notch

Left ventricle

Left atrium

EDV

SV

Aorta

T

Vent

ricul

arvo

lum

e (m

l)Pr

essu

re (m

m H

g)


Cardiac Output (CO)

• Volume of blood pumped by each ventricle in one minute

• CO = heart rate (HR) x stroke volume (SV)• HR = number of beats per minute

• SV = volume of blood pumped out by a ventricle with each beat


Venousreturn Contractility Sympathetic

activityParasympathetic

activity

EDV(preload)

Strokevolume

Heartrate

Cardiacoutput

ESV

Exercise (byskeletal muscle andrespiratory pumps;

see Chapter 19)

Heart rate(allows more

time forventricular

filling)

Bloodborneepinephrine,

thyroxine,excess Ca2+

Exercise,fright, anxiety

Initial stimulus

ResultPhysiological response


Chemical Regulation of Heart Rate

1. Hormones• Epinephrine and thyroxine enhance heart

rate and contractility

2. Intra- and extracellular ion concentrations (e.g., Ca2+ and K+) must be maintained for normal heart function


Other Factors that Influence Heart Rate

• Age

• Gender

• Exercise

• Body temperature



• Tachycardia: abnormally fast heart rate (>100 bpm)• If persistent, may lead to fibrillation

• Bradycardia: heart rate slower than 60 bpm• May result in grossly inadequate blood

circulation

• May be desirable result of endurance training

Figure 18.1a

Documents

Transcript of Figure 18.1a