Internal Heart

Define the layers of the heart

Pericardium : Serous Layer (parietal pericardium) and Fibrous Layer

Epicardium : (visceral pericardium) outer layer of heart, visceral layer of pericardium, composed of mesothelium , excretes serous fluid so heart can contract without creating friction on pericardial wall

Myocardium: Middle layer , composed of muscle that contracts the heart

Endocardium: Inner layer, continuous with endothelium

Cardiac Skeleton

Dense, fibrous connective tissue

4 rings are connected by the fibrous trigone which is a thickened area of connective tissue: fibrous ring of pulmonary valve, aortic valve, left atrioventricular ring, right atrioventricular ring

Separates atria and ventricles

The rings connect in the same plane between the atria and ventricles

Semilunar Valves

Aortic and Pulmonary

Cusps that prevent blood back flow

Arterial Flow

AV Valves

Venous flow

Function of Cardiac Skeleton

Maintain the integrity of the openings

Provide attachments for the valve cusps

Separates the atria from the ventricles mechanically / structurally as well as electrically

Heart Valves

Fibroelastic CT covered by folds of endocardium that attach to the cardiac skeleton

Function: prevent back flow of blood

4 valves 2 types: Semilunar: pulmonary and aorta. Atrioventricular: Right/Tricuspid and Left/Bicuspid/Mitral

Tricuspid and Mitral valves have - and - cusps

3

2

Cusp

Leaflet of the valve

Chordae Tendineae

Tendinous cords that attaches the valvular cusps to the papillary muscles

Function: Prevent separation and inversion of the cusps into the right atrium when tension increases during ventricular contraction

Papillary Muscles

are conical muscular projections from the ventricular wall

Pull the chordae tendineae towards the myocardium. Contraction adds tension to the chordae tendineae thus preventing inversion (prolaspse) of the valve during ventricular contraction.

Tricuspid has 3 of them: Anterior, Posterior, Septal

Bicuspid has 2: Anterior and Posterior

Semilunar Valves started with — outflow tract and derived from —. During development that got divided and turned into the —- and ——.

one

Truncus arteriosus

Pulmonary Trunk - anterior cusp

Aorta - posterior cusp

Semilunar heart valves each have - pocket like cusps: —-,—-,—-

Aortic has openings in the — and — sinuses to fill the —- arteries

Their function is to

3 ; Left, Right, Posterior/Anterior

Right and Left ; Coronary

Function: Prevent back flow of blood into the ventricles

Valvular Dysfunction

Stenosis (narrowing of valve, prevent from fully opening) or Insufficiency/Regurgitation (nodule develops preventing valve cusps from meeting properly when they close)

Force heart to work harder, lead to murmurs, can be insignificant or deadly

Treatment: valve replacement

Cardiac Cycle

Diastole: Relaxation of chambers - AV Valves open - blood flows in as ventricles expand, NO Sounds should occur, even when atria contract and top off ventricles should still make NO Sound

Systole: When ventricles start to contract and AV Valves slap shut is when you should hear the first S1 heart sound and when Systole begins.

Semilunar valves open up no heart sound

Beginning of diastole, upon closure of aortic and pulmonary valves, is when you hear S2 heart sound

S1 Heart Sound:

S2 Heart Sound:

AV Valves slap shut (LUB)

Semilunar valves slap shut (DUB)

During systole blood is pushed out the —- valves

Semilunar

Left AV Valve Best Sound

5th intercostal space under left nipple

Aortic Valve (left) Best Sound

2nd intercostal space right of sternum

Right AV Valve Best Sound

5th intercostal space left of sternum

Pulmonary Valve (right side) Best Sound

2nd intercostal space left of sternum

Right Atrium has a — and — aspect.

Receives deoxygenated blood from the —-

smooth, rough

SVC, IVC, and Coronary Sinus.

Right Atrium has —- —— —- and —-

SVC, IVC, Coronary Sinus, Crista Terminalis

The Crista terminalis divides atrium into — and — areas

Smooth, Rough

Smooth = Sinus of Vena Cava (aka Sinus Venarum). Posterior, Thin walled, contains openings for the SVC, IVC, and coronary sinus. Origin = right horn of sinus venosus.

Rough = Right Auricle/Atrium. Anterior. Muscular wall composed of pectinate muscles. Origin = embryonic primitive atrium.

Following crista terminalis up to SVC is where you will find the —

SA Nodal Tissue

Interatrial septum seperates the — and — atria.

Marked by the —- which is a remnant of the foramen ovale. Foramen ovale seen in developing fetus but closes shortly after birth.

Right , Left

Fossa Ovalis

— or the — allows blood to flow from the right atrium to the right ventricle

Tricuspid Valve or Right Atrioventricular Valve

Tricuspid Cusps (leaflets) If attaches anterior it is —- and posterior it is —- and third one is —-

anterior cusp

posterior cusp

septal cusp (more superior, attaches to septum)

Interior of right ventricle has irregular muscular elevations called the —

— aka the moderator band extends from the interventricular septum to the anterior papillary muscle. Carries the Purkinje fibers of the cardiac conduction system

—- aka — cone shaped and smooth. Leads to pulmonary trunk and valve.

Trabeculae Carnae

Septomarginal trabecula

Conus Arteriosus, Infundibulum

Poorly oxygenated blood leaves the ventricles through the —

pulmonic valve from right ventricle

Oxygenated blood enters the left atrium via the —-

Pulmonary veins

Left atrium has — and — walled areas

Smooth , Rough

Smooth = posterior half of atrium , origin - embryonic pulmonary veins

Rough = anterior half of atrium with pectinate muscles. origin - embryonic primitive atrium

Oxygenated blood leaves the left atrium via the —- and flows into the left ventricle

Mitral valve (atrioventricular)

Which ventricle is bigger

Left

Walls 2-3 times thicker

Trabeculae carneae are finer and more numerous

Conical cavity is longer

Anterior and posterior papillary muscles are larger

Volume is physiologically same as the right ventricle

Superior and anterior walls of the left ventricle form the —- which is smooth, and non-muscular

Aortic Vestibule

Interventricular septum has 2 parts

Muscular part (thick) and Membranous part (thin, upper part of septum)

Blood is pushed out of the left ventricle through the — to the aorta.

aortic valve (semilunar)

Left Ventricular Hypertrophy

Myocardium of left ventricle becomes thickened

Due to: high blood pressure, valve disease, genetic

As muscles become thicker, becomes less effective. Pumping blood becomes harder.

Heart is a — organ made of muscle

hollow

Skeletal myocytes of heart

have the same fiber orientation w/ in a muscle belly

contractile force is in the same direction

pull on the same bones

timing and coordination is not an imperative for function

Cardiac myocytes of heart

have different fiber orientation w/ in the heart

contractile force is in various directions

pull on neighboring myocytes

timing and coordination is an IMPERATIVE for function

Conduction system

Nodal tissue and highly specialized conducting fibers initiate and transmit action potentials throughout the heart to produce the coordinated contractions of the cardiac cycle

Nodal tissues

Sino-atrial node (SA)

Atrioventricular node (AV)

Specialized Conducting Fibers

Atrioventricular bundle

Right and left bundle branches

Subendocardial plexus (Purkinje fibers)

Distribution of conduction tissue and the insulation of fibrous cardiac skeleton allows for a — pathway of excitation and contraction.

Unidirectional

AV Node is by the

Function

AV bundle is the ONLY electrical connection between the — and — myocardium

Tricuspid valve and opening of coronary sinus

Function: distribute signal through the AV bundle to the ventricles

Atrial and Ventricular

SA node is by the

SVC and right atrium

SA Node is the

Pacemaker of the heart.

Initiates and regulates action potentials for the contractions of the heart.

Impulse is ~70 times per minute.

Excitation signal spreads across both atria causing the muscles to contract

Stimulation rate increases via sympathetics and decreases via parasympathetics

Signal from the SA node travels though the walls of the —- to stimulate the AV node

Right Atrium

AV Bundles passes from AV node through the — skeleton.

Along the membranous part of the —.

Divides into the — and — —, at the junction of the membranous and muscular parts of the interventricular septum.

Branches into the —-. Extend into the walls of the ventricles to stimulate the ventricular musculature. Also stimulates the papillary muscles.

Fibrous

Interventricular Septum

Right and Left Bundles

Subendocardial Plexus (AKA Purkinje Fibers)

Conduction System Summary

SA to AV to AV bundle to L and R Purkinje fibers

Innervation

Sympathetic:

Parasympathetic:

OMM Consideration:

Sympathetic: T1-T5. SA and AV Nodes and cardiac muscle (innervate the heart at large)

Parasympathetic: Vagus Nerve (CN X). SA and AV nodal tissue

OMM Consideration: treat the affected spinal segments

Sudden cardiac death is a pathology related to

Arrhythmias - lack of coordination bw cardiac myocytes’ contraction