c hapter 18 the cardiovascular system: the heart: part a
TRANSCRIPT
CHAPTER 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 diaphragmTwo-thirds to the left of the midsternal lineAnterior to the vertebral column, posterior
to the sternum Enclosed in pericardium, a double-walled
sac
PLAYPLAY Animation: Rotatable heart
Copyright © 2010 Pearson Education, Inc. Figure 18.1a
Point ofmaximalintensity(PMI)
Diaphragm
(a)
Sternum
2nd rib
Midsternal line
Copyright © 2010 Pearson Education, Inc. Figure 18.1c
(c)
Superiorvena cava
Left lung
AortaParietalpleura (cut)
Pericardium(cut)
Pulmonarytrunk
Diaphragm
Apex ofheart
PERICARDIUMSuperficial 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 pericardium
Parietal layer ofserous pericardiumPericardial cavity
Epicardium(visceral layerof serouspericardium)Myocardium
Endocardium
Pulmonarytrunk
Heart chamber
Heartwall
Pericardium
Myocardium
LAYERS OF THE HEART WALL1. Epicardium—visceral layer of the serous
pericardium
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
LAYERS OF THE HEART WALL
3. Endocardium is continuous with endothelial lining of blood vessels
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
CHAMBERS
Four chambersTwo 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 ventriclesSeparated by the
interventricular septumAnterior 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 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
ATRIA: THE RECEIVING CHAMBERS
Walls are ridged by pectinate muscles
Vessels entering right atriumSuperior vena cava Inferior vena cavaCoronary sinus
Vessels entering left atriumRight 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 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
PATHWAY OF BLOOD THROUGH THE HEART
The heart is two side-by-side pumpsRight side is the pump for the
pulmonary circuitVessels that carry blood to and from the lungs
Left side is the pump for the systemic circuitVessels 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
PATHWAY OF BLOOD THROUGH THE HEART
Right atrium tricuspid valve right ventricle
Right ventricle pulmonary semilunar valve pulmonary trunk pulmonary arteries lungs
Lungs pulmonary veins left atrium Left atrium bicuspid valve left ventricle Left ventricle aortic semilunar valve
aorta systemic circulation Systemic circulation vena cavae Right atrium
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
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
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
HOMEOSTATIC IMBALANCES
Angina pectorisThoracic pain caused by a fleeting
deficiency in blood delivery to the myocardium
Cells are weakened Myocardial infarction (heart attack)
Prolonged coronary blockageAreas of cell death are repaired with
noncontractile scar tissue
HEART VALVES
Ensure unidirectional blood flow through the heart
Atrioventricular (AV) valvesPrevent backflow into the atria when
ventricles contractTricuspid valve (right)Mitral valve (left)
Chordae tendineae anchor AV valve cusps to papillary muscles
HEART VALVESSemilunar (SL) valves
Prevent backflow into the ventricles when ventricles relax
Aortic semilunar valvePulmonary semilunar valve
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. 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 valve
Chordaetendineae
Interventricularseptum
Myocardiumof left ventricle
Opening of inferiorvena cava
Tricuspid 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
Aorta
Pulmonarytrunk
MICROSCOPIC ANATOMY OF CARDIAC MUSCLE
Cardiac muscle cells are striated, short, fat, branched, and interconnected
Numerous large mitochondria (25–35% of cell volume)
Intercalated discs: junctions between cells anchor cardiac cells
Heart muscle behaves as a functional syncytium
Copyright © 2010 Pearson Education, Inc. Figure 18.11a
Nucleus
DesmosomesGap junctions
Intercalated discs Cardiac muscle cell
(a)