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Copyright © 2010 Pearson Education, Inc.
Marieb Chapter 18 Part A: The Heart
CABG
Copyright © 2010 Pearson Education, Inc.
How Hard Does Our Heart Work?
Copyright © 2010 Pearson Education, Inc. Figure 18.2
Fibrous pericardium
Parietal layer ofserous pericardiumPericardial cavity
Epicardium(visceral layerof serouspericardium)Myocardium
Endocardium
Pulmonarytrunk
Heart chamber
Heartwall
Pericardium
Myocardium
Copyright © 2010 Pearson Education, Inc.
Layers of the Heart Wall
1. Epicardium — visceral layer of the serous pericardium
2. Myocardium - contractile muscle and conduction system
• 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 (non-conductive)
• Provides a framework so muscles don’t affect each other when they contract
3. Endocardium is continuous with blood vessel endothelium
Copyright © 2010 Pearson Education, Inc. Figure 18.4b
(b) Anterior view
Brachiocephalic trunk
Superior vena cava
Right pulmonaryarteryAscending aortaPulmonary trunk
Right pulmonaryveins
Right atrium
Right coronary artery(in coronary sulcus)Anterior cardiac vein
Right ventricle
Right marginal artery
Small cardiac vein
Inferior vena cava
Left common carotidarteryLeft subclavian artery
Ligamentum arteriosum
Left pulmonary artery
Left pulmonary veins
Circumflex artery
Left coronary artery(in coronary sulcus)
Left ventricle
Great cardiac vein
Anterior interventricularartery (in anteriorinterventricular sulcus)
Apex
Aortic arch
Auricle ofleft atrium
Copyright © 2010 Pearson Education, Inc. Figure 18.4e
Aorta
Left pulmonaryarteryLeft atriumLeft pulmonaryveins
Mitral (bicuspid)valve
Aortic valve
Pulmonary valveLeft ventricle
Papillary muscleInterventricularseptumEpicardiumMyocardiumEndocardium
(e) Frontal section
Superior vena cava
Right pulmonaryarteryPulmonary trunk
Right atrium
Right pulmonaryveinsFossa ovalisPectinate muscles
Tricuspid valveRight ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
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
Two Circuits
Copyright © 2010 Pearson Education, Inc.
Pathway of Blood Through Circuits
• 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 (LV size >>> RV size)
• Coronary circuit is a part of the
Copyright © 2010 Pearson Education, Inc. Figure 18.6
Rightventricle
Leftventricle
Interventricularseptum
Copyright © 2010 Pearson Education, Inc.
Coronary Circuit
• The functional blood supply to the heart muscle itself
• Arteries connect to other arteries via anastomoses (junctions) (ex: R and L coronary circulations)
• On surface:
• In the muscle:
• RT coronary artery serves:
• L coronary artery serves:
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
Aorta
Left pulmonaryartery
Left pulmonaryveinsAuricle of leftatriumLeft atrium
Great cardiacvein
Posterior veinof left ventricle
Left ventricle
Apex
Superior vena cava
Right pulmonary artery
Right pulmonary veins
Right atrium
Inferior vena cava
Right coronary artery(in coronary sulcus)
Coronary sinus
Posteriorinterventricularartery (in posteriorinterventricular sulcus)Middle cardiac veinRight ventricle
Copyright © 2010 Pearson Education, Inc.
Homeostatic Imbalances• Angina pectoris
• Occurs because of atherosclerosis in coronary arteries
• Emotion, physical stress, etc. cause HR and contractility to increase
• Clogged arteries can’t meet the demand for oxygen and nutrients
• Thoracic pain results
• Stop activity, take a vasodilator; pain subsides
• No cell death because it is a temporary situation
• Sign of CAD
Copyright © 2010 Pearson Education, Inc.
Homeostatic Imbalances• Myocardial infarction (heart attack)
• Prolonged coronary blockage
• Plaque alone
• Plaque + clot
• Plaque embolizes
• Vessel spasm
• Areas of cell death are repaired with non-contractile scar tissue
Copyright © 2010 Pearson Education, Inc.
What Happens After A MI?
• Dead cells are replaced by non-contractile scar tissue (collagen)
•Non-contractile
•Non-conductive
•Stiffens the heart
• If the heart attack is severe, the heart might go into ventricular fibrillation or not pump well enough to maintain the perfusion of tissues and BP
Copyright © 2010 Pearson Education, Inc.
What Does a MI Look Like?
Copyright © 2010 Pearson Education, Inc.
Heart Valves• Ensure unidirectional blood flow through the heart
• Valves can be damaged by
• Types of damage
• Incompetence/insufficiency
• Stenosis
Copyright © 2010 Pearson Education, Inc.
Heart Valves
Copyright © 2010 Pearson Education, Inc. Figure 18.8a
Pulmonary valveAortic valveArea of cutaway
Mitral valveTricuspid valve
Myocardium
Tricuspid(right atrioventricular)valveMitral(left atrioventricular)valveAorticvalve
Pulmonaryvalve
(b)
Pulmonary valveAortic valveArea of cutaway
Mitral valveTricuspid valve
Myocardium
Tricuspid(right atrioventricular)valve
(a)
Mitral(left atrioventricular)valveAortic valve
Pulmonaryvalve
Fibrousskeleton
Anterior
Copyright © 2010 Pearson Education, Inc.
Nucleus
DesmosomesGap junctions
Intercalated discs Cardiac muscle cell
(a)
Microscopic Anatomy of Cardiac Muscle
Copyright © 2010 Pearson Education, Inc.
Microscopic Anatomy of Cardiac Muscle
• Intercalated discs: junctions between cells anchor cardiac cells
• Desmosomes prevent cells from separating during contraction
• Gap junctions allow ions to pass; electrically couple adjacent cells
• Heart muscle behaves as a functional syncytium ( )