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Chapter 18: Anatomy of the Cardiovascular SystemSummary:
Anatomy of the Heart is:
4 chambers4 valves
4 great vessels
3 layered covering3 layered wall
3 circuits
The Heart is a muscular PUMP
(size and shape of a
fist) with 4 Chambers
The upper chambers ( R atrium, L atrium ) are for receiving Blood
The lower chambers (R Ventricle, L Ventricle) are for pumping blood
Right Atrium Left AtriumRight Ventricle Left Ventricle
RA
RV
LA
LV
Right and Left Atria separated by the membranous ATRIAL SEPTUM
(valves separate RA/RV,
LA/LV)
Ventricles separated by the muscular INTERVENTRICULAR SEPTUM
RA LA
RV LV
--- -- --- -- -- - --- --- ---
• Located in the MEDIASTINUM of the THORACIC CAVITY,
between the Right and Left Lungs, posterior to the body of STERNUM, Anterior to Thoracic Vertebrae 5-8.
Sits atop the diaphragm
4 CARDIAC VALVES
The Heart has 4 valves,
important in regulating the
filling &
flowing of the chambers of the
bloodTRICUSPID VALVE (Right Atrium / Right Ventricle)
MITRAL VALVE (Left Atrium / Left Ventricle) PULMONIC VALVE (right Ventricle / Pulmonary trunk {artery} ) AORTIC VALVE (Left Ventricle / Aorta)
RA
RV
LA
LV
The Atrioventricular valves (tricuspid and mitral)are composed of flat flaps (cusps), are connected to the interior ventricular walls viaConnective tissue chords -- (CHORDAE TENDONAE), andPAPILLARY MUSCLES.
The Pulmonic and the Aortic Valves are semilunar valves,Each with three billowy, pocket-like leaflets
Mitral valve
Chordaetendonae
Papillarymuscle
Tricuspid valve
Chordae tendonae
Pulmonic valve
Aortic valve
Auricles of Right and Left Atria On both the Right & the Left Atrium,
there is an ear-like extension called the Auricle these are visible on the external surface of the heart:
Auricle of right atrium
Auricle of right atrium
Left ventricle
RA
RV
Apex of the heart
The HEART and GREAT VESSELS
Each of the 4 cardiac chambers is associated with Major Blood vessel/s: (entering or exiting)
Right Atrium : (in) Superior & Inferior Vena Cavae
Right ventricle: Pulmonary Trunk (R & L pulm. arteries)
(out)
Left Atrium: (in) Pulmonary veins Left Ventricle: Aorta (out)
Inferior Vena Cava
Superior Vena Cava Aorta
Pulmonary Trunk:R & L Pulmonary arteries
Pulmonary veins
(more on these to follow)
(Anterior view)
Note: red oxygenated, blue unoxygenated blood
vena cavae, aortic arch, pulmonary trunk, pulmonary veins
To remember great vessels: in order
VC, AA, PT, PV
Triple layered Covering of the heart: PERICARDIAL SACHeart coverings protect against friction
Fibrous Pericardium: the thick, tough outer sac, which is lined
By the Serous Pericardium: a thin, moist
double membrane, the parietal layer, which lines the
fibrous pericardium, and the visceral layer, which adheres to &
covers the heart, it is also known as THE EPICARDIUM
Coverings of the Heart Fibrous pericardium Serous pericardium (two-layered)
Parietal layer lines fibrous pericardium Visceral layer (epicardium) forms
outermost part of heart wall
3 Layers of the heart wall Epicardium: thin , moist - is the visceral
pericardial membrane
MYOCARDIUM - the Heart Muscle, the left ventricular wall is three times as
thick as the right ventricle
ENDOCARDIUM - the inner lining, made up of single layer of ENDOTHELIUM,
( endothelium also lines the blood vessels of the entire CVS)
Ventricles ( FYI ) Two lower chambers known as pumping chambers because, upon contraction, they push blood into the large network of vessels
Ventricular myocardium is thicker than the atrial myocardium because great force must be generated to pump the blood a large distance, against systemic resistance. Myocardium of left ventricle is thicker than the right for same reasons – distance and increased resistance.
2 3 CIRCUITS A. PULMONARY CIRCUIT: Right heart: unoxygenated blood from SVC & IVC Right Atrium >>> Right Ventricle>>> Pulmonary Trunk Right and left Pulmonary arteries, into the LUNGS, for gases exchange; then to Heart via Pulm veins B. SYSTEMIC CIRCUIT: Left heart: oxygenated blood from PULM VeinsLeft atrium >>> Left Ventricle >>> Aorta , and the systemic arterial, capillary, venous network
C. CORONARY CIRCULATION: blood flow to the heart
***Flow of Blood Through Heart*** Right side of heart is pulmonary
circuit pump Left side of heart is systemic
circuit pumpright atrium (tricuspid valve) -> right
ventricle (pulmonary SL valve) -> lungs -> left atrium (bicuspid (mitral) valve) -> left ventricle (aortic SL valve) -> body tissues
Lung Bypasses in Fetal Heart Foramen ovale – opening between right
&left atria; after birth closes to form fossa ovalis.
Ductus arteriosus – connection between pulmonary trunk & aorta; closes to form ligamentum arteriosum.
CORONARY ARTERIES:BLOOD SUPPLY TO THE HEART
THE FIRST BRANCHES off the AORTA, immediately superior to the Aortic
valve: RIGHT CORONARY ARTERY, LEFT MAINSTEM CORONARY ARTERY, with its 2 quick branches: LEFT
CIRCUMFLEX, LEFT ANTERIOR
DESCENDING. Coronary blood flow actually occurs when
the aortic valve cusps are closed, during back-flow; not during the powerful “systolic” pulsation of blood out of the ventricle during contraction.
CORONARY VEINS
Veins of the coronary circulation As a rule, veins follow a course that closely parallels that of coronary arteries.
After going through cardiac veins, blood enters the CORONARY SINUS to drain into the right atrium
Several veins drain directly into the right atrium