heart: part a mount royal college system: the ... · copyright © 2010 pearson education, inc....

PowerPoint® Lecture Slides prepared by Janice Meeking, Mount Royal College

C H A P T E R

Copyright © 2010 Pearson Education, Inc.

18 The Cardiovascular System: The Heart: Part A


Heart Anatomy

• Approximately the size of a fist

• Location• In the mediastinum between second rib and fifth

intercostal space

• On the superior surface of diaphragm

• Two-thirds to the left of the midsternal line

• Anterior to the vertebral column, posterior to the sternum

• Enclosed in pericardium, a double-walled sac

Copyright © 2010 Pearson Education, Inc. Figure 18.1c

(c)

Superiorvena cava

Left lung

AortaParietalpleura (cut)

Pericardium(cut)

Pulmonarytrunk

DiaphragmApex ofheart


Pericardium

•Superficial fibrous pericardium•Protects, anchors, and prevents overfilling


Pericardium

•Deep two-layered serous pericardium• Parietal layer lines the internal surface of the

fibrous pericardium

• Visceral layer (epicardium) on external surface of the heart

• Separated by fluid-filled pericardial cavity (decreases friction)

Copyright © 2010 Pearson Education, Inc. Figure 18.2

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

Pulmonarytrunk

Heart chamber

Heartwall

PericardiumMyocardium


Layers of the Heart Wall

1. Epicardium—visceral layer of the serous pericardium



2. Myocardium • Spiral bundles of cardiac muscle cells

• Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue

• Anchors cardiac muscle fibers

• Supports great vessels and valves

• Limits spread of action potentials to specific paths



3. Endocardium is continuous with endothelial lining of blood vessels


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

Pulmonarytrunk

Heart chamber

Heartwall

PericardiumMyocardium


Cardiacmusclebundles


Chambers

•Four chambers• Two atria

•Separated internally by the interatrial septum

•Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles

•Auricles increase atrial volume


Chambers

•Two ventricles• Separated by the interventricular septum

• Anterior and posterior interventricular sulci mark the position of the septum externally

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 ventricleRight 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

Aorta

Left pulmonaryarteryLeft atriumLeft pulmonaryveins

Mitral (bicuspid)valve

Aortic valvePulmonary valveLeft ventriclePapillary muscleInterventricularseptumEpicardiumMyocardiumEndocardium

(e) Frontal section

Superior vena cavaRight pulmonaryarteryPulmonary trunkRight atrium

Right pulmonaryveinsFossa ovalisPectinate musclesTricuspid valveRight ventricleChordae 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

Heart

Left ventricleRight atrium

Right ventricle

Venae cavae



•Right atrium → tricuspid valve → right ventricle

•Right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs

PLAY Animation: Rotatable heart (sectioned)

http://rotatable_heart_sectioned.mov


PLAY Animation: Rotatable heart (sectioned)


•Lungs → pulmonary veins → left atrium

•Left atrium → bicuspid valve → left ventricle

•Left ventricle → aortic semilunar valve → aorta

•Aorta → systemic circulation

http://rotatable_heart_sectioned.mov



•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

•Anatomy of the ventricles reflects these differences


Rightventricle

Leftventricle

Interventricularseptum


Coronary Circulation

•The functional blood supply to the heart muscle itself

•Arterial supply varies considerably and contains many anastomoses (junctions) among branches

•Collateral routes provide additional routes for blood delivery


Coronary Circulation

•Arteries • Right and left coronary (in atrioventricular

groove), marginal, circumflex, and anterior interventricular arteries

•Veins • Small cardiac, anterior cardiac, and great

cardiac veins

Copyright © 2010 Pearson Education, Inc. Figure 18.7a

Rightventricle

Rightcoronaryartery

Rightatrium

Rightmarginalartery

Posteriorinterventricularartery

Anteriorinterventricularartery

Circumflexartery

Leftcoronaryartery

Aorta

Anastomosis(junction ofvessels)

Leftventricle

Superiorvena cava

(a) The major coronary arteries

Left atrium

Pulmonarytrunk


Superiorvena cava

Anteriorcardiacveins

Small cardiac vein

Middle cardiac vein

Greatcardiacvein

Coronarysinus

(b) The major cardiac veins

Copyright © 2010 Pearson Education, Inc. Figure 18.4d

(d) Posterior surface view

AortaLeft pulmonaryarteryLeft pulmonaryveinsAuricle of leftatriumLeft atrium

Great 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


What to be working on… → Sheep Heart Dissection Pre Lab

→ Genetics Practice: Blood Type

→ Blood Transfusion Game (link on my website!)

→ Blood Cell Flashcards (checking these on Thursday/Friday!)

→ Blood Flow Story (due Monday 5/8)

→ Column 3 terms (check on Mon 5/8)

→ Any other packet work →

Running Checklist…→ Blood Introduction→ Dive Case Study→ 17A Notes→ Blood Pressure Practice→ Blood Flow Notes→ Cardiovascular Fitness Lab→ Human Heart Anatomy and Circulation Wksht→ 17B Notes→ Blood Cell Flashcards→ Unit Guide


Happy Monday!

Please have out (or access to, virtually) your Blood Flow Story!! Be ready to share in your small groups.



Start at the lungs!!!

→ Be sure to include ALL major chambers, major arteries/veins and valve names


Take out your 18B Notes!

Warm Up

What is the difference between pulmonary, systemic and

coronary circulation?


Heart Valves

• Ensure unidirectional blood flow through the heart

• Atrioventricular (AV) valves• Prevent backflow into the atria when ventricles

contract

• Tricuspid valve (right)

• Mitral valve (left)

•Chordae tendineae anchor AV valve cusps to papillary muscles


Heart Valves

•Semilunar (SL) valves• Prevent backflow into the ventricles when

ventricles relax

• Aortic semilunar valve

• Pulmonary semilunar valve


Pulmonary valveAortic valveArea of cutawayMitral valveTricuspid valve

MyocardiumTricuspid(right atrioventricular)valveMitral(left atrioventricular)valveAorticvalvePulmonaryvalve

(b)

Pulmonary valveAortic valveArea of cutawayMitral valveTricuspid valve Myocardium

Tricuspid(right atrioventricular)valve

(a)

Mitral valve(left atrioventricular)

Aortic valvePulmonaryvalveFibrous

skeletonAnterior


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 flow

Atrium

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


Heart Physiology: Sequence of Excitation

1. Sinoatrial (SA) node (pacemaker)• Generates impulses about 75 times/minute

(sinus rhythm)

• Depolarizes faster than any other part of the myocardium



2. Atrioventricular (AV) node• Smaller diameter fibers; fewer gap junctions

• Delays impulses approximately 0.1 second

• Depolarizes 50 times per minute in absence of SA node input



3. Atrioventricular (AV) bundle (bundle of His)• Only electrical connection between the atria

and ventricles



4. Right and left bundle branches• Two pathways in the interventricular septum

that carry the impulses toward the apex of the heart



5. Purkinje fibers• Complete the pathway into the apex and

ventricular walls

• AV bundle and Purkinje fibers depolarize only 30 times per minute in absence of AV node input


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

Internodal pathway

Superior vena cava Right 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


Extrinsic Innervation of the Heart

•Heartbeat is modified by the ANS

•Cardiac centers are located in the medulla oblongata• Cardioacceleratory center innervates SA and

AV nodes, heart muscle, and coronary arteries through sympathetic neurons

• Cardioinhibitory center inhibits SA and AV nodes through parasympathetic fibers in the vagus nerves


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 the action potentials generated by nodal and contractile cells at a given time

• Three waves1. P wave: depolarization of SA node

2. QRS complex: ventricular depolarization

3. T wave: ventricular repolarization


Sinoatrialnode

Atrioventricularnode

Atrialdepolarization

QRS complex

Ventriculardepolarization Ventricular

repolarization

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



P

R

T

QS

SA node

AV node

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

P

R

T

QS


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 mid-to-late diastole• AV valves are open • 80% of blood passively flows into ventricles• Atrial systole occurs, delivering the remaining

20%• End diastolic volume (EDV): volume of blood

in each ventricle at the end of ventricular diastole



2. Ventricular systole• Atria relax and ventricles begin to contract • Rising ventricular pressure results in closing of AV

valves• Isovolumetric contraction phase (all valves are

closed)• In ejection phase, ventricular pressure exceeds

pressure in the large arteries, forcing the SL valves open

• End systolic volume (ESV): volume of blood remaining in each ventricle



3. Isovolumetric relaxation occurs in early diastole• Ventricles relax

• Backflow of blood in aorta and pulmonary trunk closes SL valves and causes dicrotic notch (brief rise in aortic pressure)


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


Autonomic Nervous System Regulation

•Sympathetic nervous system is activated by emotional or physical stressors• Norepinephrine causes the pacemaker to fire

more rapidly (and at the same time increases contractility)


Autonomic Nervous System Regulation

•Parasympathetic nervous system opposes sympathetic effects • Acetylcholine hyperpolarizes pacemaker cells

by opening K+ channels

•The heart at rest exhibits vagal tone (parasympathetic)


Chemical Regulation of Heart Rate

1. Hormones• Epinephrine from adrenal medulla enhances

heart rate and contractility

• Thyroxine increases heart rate and enhances the effects of norepinephrine and epinephrine

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


Age-Related Changes Affecting the Heart

•Sclerosis and thickening of valve flaps

•Decline in cardiac reserve

•Fibrosis of cardiac muscle

•Atherosclerosis


Warm Up

1) Which valve is responsible for preventing blood flow back into the right ventricle?

2) Which valve is responsible for preventing blood flow back into the left ventricle?

3) Which valve is responsible for allowing blood into the right ventricle?

4) Which valve is responsible for allowing blood into the left ventricle?


Heart Contraction Jigsaw

→ Assign each group member a role

→ Feel free to use textbook and/or notes!

→ Teach each other for review!!! (don’t just let your partners copy your paper)

heart: part a mount royal college system: the ... · copyright © 2010 pearson education, inc....

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