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 blood

TRICUSPID 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

LALV

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

Heart: posterior view

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

Systemic & Pulmonary Circuits

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.

(systole) (diastole)

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

anterior

posterior

posterior