heart: part a mount royal college system: the ... · copyright © 2010 pearson education, inc....
TRANSCRIPT
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
Copyright © 2010 Pearson Education, Inc.
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
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Pericardium
•Superficial fibrous pericardium•Protects, anchors, and prevents overfilling
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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
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Layers of the Heart Wall
1. Epicardium—visceral layer of the serous pericardium
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Layers of the Heart Wall
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
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Layers of the Heart Wall
3. Endocardium is continuous with endothelial lining of blood vessels
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 18.3
Cardiacmusclebundles
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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
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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
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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
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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
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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
Copyright © 2010 Pearson Education, Inc. Figure 18.5
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
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Pathway of Blood Through the Heart
•Right atrium → tricuspid valve → right ventricle
•Right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs
PLAY Animation: Rotatable heart (sectioned)
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PLAY Animation: Rotatable heart (sectioned)
Pathway of Blood Through the Heart
•Lungs → pulmonary veins → left atrium
•Left atrium → bicuspid valve → left ventricle
•Left ventricle → aortic semilunar valve → aorta
•Aorta → systemic circulation
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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
•Anatomy of the ventricles reflects these differences
Copyright © 2010 Pearson Education, Inc. Figure 18.6
Rightventricle
Leftventricle
Interventricularseptum
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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
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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
Copyright © 2010 Pearson Education, Inc. Figure 18.7b
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
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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
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Happy Monday!
Please have out (or access to, virtually) your Blood Flow Story!! Be ready to share in your small groups.
Copyright © 2010 Pearson Education, Inc.
Pathway of Blood Through the Heart
Start at the lungs!!!
→ Be sure to include ALL major chambers, major arteries/veins and valve names
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Take out your 18B Notes!
Warm Up
What is the difference between pulmonary, systemic and
coronary circulation?
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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
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Heart Valves
•Semilunar (SL) valves• Prevent backflow into the ventricles when
ventricles relax
• Aortic semilunar valve
• Pulmonary semilunar valve
Copyright © 2010 Pearson Education, Inc. Figure 18.8a
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
Copyright © 2010 Pearson Education, Inc. Figure 18.8b
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)
Copyright © 2010 Pearson Education, Inc. Figure 18.9
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)
Copyright © 2010 Pearson Education, Inc. Figure 18.10
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
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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
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Heart Physiology: Sequence of Excitation
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
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Heart Physiology: Sequence of Excitation
3. Atrioventricular (AV) bundle (bundle of His)• Only electrical connection between the atria
and ventricles
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Heart Physiology: Sequence of Excitation
4. Right and left bundle branches• Two pathways in the interventricular septum
that carry the impulses toward the apex of the heart
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Heart Physiology: Sequence of Excitation
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
Copyright © 2010 Pearson Education, Inc. Figure 18.14a
(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
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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
Copyright © 2010 Pearson Education, Inc. Figure 18.15
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
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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
Copyright © 2010 Pearson Education, Inc. Figure 18.16
Sinoatrialnode
Atrioventricularnode
Atrialdepolarization
QRS complex
Ventriculardepolarization Ventricular
repolarization
P-QInterval
S-TSegment
Q-TInterval
Copyright © 2010 Pearson Education, Inc. Figure 18.17
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
Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 2
Atrial depolarization, initiated bythe SA node, causes the P wave.
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
Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 3
Atrial depolarization, initiated bythe SA node, causes the P wave.
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
DepolarizationRepolarization
1
2
3
Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 4
Ventricular depolarization iscomplete.
P
R
T
QS
DepolarizationRepolarization
4
Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 5
Ventricular depolarization iscomplete.
Ventricular repolarization beginsat apex, causing the T wave.
P
R
T
QS
P
R
T
QS
DepolarizationRepolarization
4
5
Copyright © 2010 Pearson Education, Inc. Figure 18.17, step 6
Ventricular depolarization iscomplete.
Ventricular repolarization beginsat apex, causing the T wave.
Ventricular repolarization iscomplete.
P
R
T
QS
P
R
T
QS
P
R
T
QS
DepolarizationRepolarization
4
5
6
Copyright © 2010 Pearson Education, Inc. Figure 18.17
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 18.18
(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.
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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
Copyright © 2010 Pearson Education, Inc. Figure 18.19
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
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Mechanical Events: The Cardiac Cycle
•Cardiac cycle: all events associated with blood flow through the heart during one complete heartbeat• Systole—contraction
• Diastole—relaxation
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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
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Phases of the Cardiac Cycle
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
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Phases of the Cardiac Cycle
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)
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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
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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)
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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)
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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
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Other Factors that Influence Heart Rate
•Age
•Gender
•Exercise
•Body temperature
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Age-Related Changes Affecting the Heart
•Sclerosis and thickening of valve flaps
•Decline in cardiac reserve
•Fibrosis of cardiac muscle
•Atherosclerosis
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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?
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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)