The Cardiovascular System (I)The Cardiovascular System (I)The HeartThe Heart

MediastinumMediastinum

MediastinumMediastinum

• The space between the 2 lungs

Sup.: FIRST RIB

Inf.: diaphragm

Ant.: sternum

Post.: VERTEBRAL COLUMN

Heart SurfacesHeart Surfaces

1. Anterior (sternocostal):

2. Inferior (diaphragmatic):

3. Base:

mostly Lf. Atrium

Posterior surface of the heart

4. Apex:

tip of Lt ventricle

Inferior Surface

Posterior Surface

Anterior Surface

Site for posterior surface of the heart (Base)

Site for inferior surface of the heart (Diaphragmatic)

Heart Borders

• Right border:

From inferior

surface to base

• Left Border

Pulmonary border

From apex to base

Surface projection• Determined by 4 points- Superior right point

3rd Rt CC- Superior left point

2nd Lt CC- Inferior left point

5th intercostal space- Inferior right point

6th Rt CC

Covering of the Heart

Coverings of the HeartCoverings of the Heart

• Covering fibroserous sac of 2 layers of tissues that encloses the heart

• Outer: fibrous (fibrous pericardium)

• Inner: serous (serous pericardium)

• Fxn.: 1. Protection 2. Lubrication (friction)

Fibrous PericardiumFibrous Pericardium

• Strong single layer of dense CT

• fuse to great vessels

• Prevent overstretching

• Protection and anchorage

Serous PericardiumSerous Pericardium

• 2 layers of mesothelial cells that are continuous with each other

• Outer (Parietal):

lines fibrous pericardium

reflects around the roots of large vessels

to become continuous with

• Inner (Visceral):

closely attached to the heart

Epicardium (outer heart layer)

Layers of the Heart wall• 3 layers:

1. Epicardium: visceral layer of serous pericardium

2. Myocardium: cardiac muscle

3. Endocardium: thin layer of endothelial cells supported by thin layer of CT

Myocarditis: inflammation of myocardium

Endocarditis: inflammation of endocardium

Fibrous Skeleton of the Heart4 rings of dense CTSurround the valvesFuse with one another

Chambers of the heart4 chambers:-2 atria

-2 ventricles

Rt ½ of Heart:Pulmonary pump

Lt ½ of Heart:Systemic pump

Right AtriumRight Atrium

- Receives deO2 bld. From the body

- Forms Rt. Border of the heart

- Composed of:smooth walled chamber &rough out pouch (auricle)

Rough = pectinate muscle

- Border between:crista terminalis

Outside:sulcus terminalis

- Atrial septum (fetal remnants): Fossa ovalis Anulus ovalis

Openings of Rt. AtriumOpenings of Rt. Atrium1. SVC:

bld. from upper body

2. IVC:

bld. From lower body / larger

4. Coronary Sinus:

Between IVC & A-V orifice

Bld form heart wall

3. A-V orifice:

Ant. to IVC

Guarded by tricuspid valve

Rt. VentricleRt. Ventricle

muscular projections:

1. Papillary muscles:

-Cone-shaped projections

-Attach the cusps of A-V valve via Chordae tendineae

2. Trabeculae carneae:

-prominent muscular ridges

OpeningsOpenings

• A-V orifice:guarded by tricuspid valve

• Pulmonary opening:opens into pulmonary trunk

guarded by pulmonary valve

Lf. AtriumLf. Atrium• Most of the base of Heart

• Inner wall:

Smooth anteriorly and posteriorly

Pectinate muscles are confined to Lt auricle

• 4 openings for P. V.: blood from lungs

• 1 opening for mitral valve

Left VentricleLeft Ventricle

• Thickest part of the Heart

• Forms apex of Heart

• papillary m.

• Chordae tendineae

• Opens into Ascending Aorta

** Ductus arteriosus

Heart ValvesHeart Valves

• 4 valves:

- 2 semilunar:

Aortic & Pulmonary

- 2 A-V:

Tricuspid & Mitral

Semilunar ValvesSemilunar Valves

• Pulmonary: 3 Crescent moon-shaped cusps

Cusp: folding of endocardium with C.T. inside

Sinus: space behind each cusp

• Aortic : similar to pulmonary

2 post. & 1 ant. Cusps

Ensures one way blood flow from ventricles into arteries

Atrioventricular ValvesAtrioventricular Valves1. Tricuspid

-Rt. A-V orifice

-3 cusps:

2. Mitral Valve:

-Left A-V orifice

-2 cusps (bicuspid)

• Cusps are Attached to papillary m. through Chordae tendineae

• Valves ensure one way flow of blood from atria to ventricles

Conducting SystemConducting System

Sino-Atrial node (SA node)

Atrio-Ventricular node (AV node)

Atrio-Ventricular Bundle & branches

(bundle of His)

Purkinje fibers

(subendocardial plexus)

Arterial Supply of the HeartArterial Supply of the Heart

• Coronary arteries:

Right Coronary artery

Left Coronary artery

• From ascending aorta

Right Coronary ArteryRight Coronary ArteryBetween pulmonary trunk & Rt. Auricle

Rt. AV groove

(Posteriorly) anastomose with

Lf. Coronary

Branches:

1. Rt. Marginal artery

2. Post. interventricular

Left Coronary ArteryLeft Coronary Artery

• Larger but shorter

• Arises between pulmonary trunk

& Lt Auricle

• Divides to:

1. ant. interventricular a.

2. circumflex a

Venous DrainageVenous Drainage

• 3 main veins Coronary Sinus

1. Great: Ant2. Middle: Post3. Small: Rt. Margin

-Anterior cardiac veinsOpen directly into Rt atrium

Blood circulation

• Pulmonary Circulation:

Rt ventricle

Lungs

Lt atrium

• Systemic Circulation:

Lt ventricle

Entire Body

Rt atrium