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Interior & Conductive System of the Heart

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The HeartThe walls of the heart are

composed of cardiac muscle.Out inward are:

epicardium,myocardium

endocardium

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The HeartIs slightly larger than a clenched fis t, working

as double self-adjusting muscular pump.

a. Human heart has four chambers

2 Atria

2 Ventriclesb. The atria lie above & are separated from the

ventricles by the atrioventricular

groove/septum

c. The atria are separated from each other byinteratrial groove & ventricles by

interventricular groove septum

Left & Right

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Interior of right atrium

a.Sulcus terminalisa vertical groove on the outer

side of heart at the junction

b/w right atrium & auricle

d.Crista terminalisinside the forms a ridge

c. Smooth posterior part main

part Sinus Vinosus

d. Rough anterior partmuscul i pact inat i or

pect inate muscles

Crista terminalis

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Openings into the Right Atriuma. SVC

b. IVCc. Coronary sinus

d. Right atrioventricular

valve

a. Many small veins

Fetal remnants

a. Fossa ovalisb. Anulus ovalis

c.Rudimentary valve of IVC

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Interior of right ventricle

a. Is a triangular chamberb.Upper part becomes funnel shaped

In fudubulum

C.Trabecu lae carneaeprojecting ridges from the

ventricular wallscomposed of 3 types

i) papillary muscle

attached with ventricular walls

and apices are connected by fibrouschords

(chordae tendineae) to cusps of the

tricuspid valve

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ii) Attached two the

ventricular walls

without the middle

part e.g. moderator

band

iii) Simply the prominentridges.

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Openings/valves in the right ventricle

a.Tricuspid valveAnterior, Septal, & inferior cusps

the bases of cusps are attached to fibrous ring

of the skeleton of the heart

free tips thru Chordae tendineae to thepapillary muscles. During the ventricular

contraction prevent the regurgitation of blood

b. Pulmonary valveGuards the pulmonary orifice

consists of 3 semilunar cusps

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Anterior semilunar cusps

Left semilunar cusps

Right semilunar cusps

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Interior of left atrium

a.The interior of the left atriumis smooth

b.Left auricle possess ridges

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Openings into the Left Atriuma.Four Pulmonary veins

b.Left atrioventricular orificeguarded by bicuspid Mitral valve

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Interior of Left Ventricle

a.The cavity s circularb. Intraventricular BP is 6 times

higher than RV

c.Well-developed trabeculae carneae,

papillary muscles but no moderatebands like right ventricle

d.Walls are 3 times thicker

than right ventricle

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Openings into the Left Ventricle

a.Bicuspid atrioventricular (Mitral) valve

Consists of two cusps (ant & post)

Similar to tricuspid valve

a.Tricuspid Aortic valve

Similar to the pulmonary valvewith right, left & posterior cusps

behind each cusp aortic wall bulges

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Skeleton of the heartConsists of fibrous rings

That surround the atrioventricular, Pulmonary

& aortic orifices

The fibrous rings support the bases of the cusps

& prevent the valves from stretching & becoming

incompetent

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Conductive system of the heart

Sinoatrial (SA) Node

Located in the wall right atrium near the opening of the SVC

Atrioventricular (AV) NodeLocated in the atrial septum near the coronary sinus

Internodal Conduction Paths

Atrioventricular Bundle

Bundle of HIS

Connects the myocardium of atria & ventricles

Left & Right bundle branches

Purkinje fiber

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