HEART I

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HEART I

• Heart is located in the mediastinum
• Area between lungs
• Contains pericardium, great blood vessels,
  oesophagus, trachea

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HEART I

• Heart is a muscular pump
• continuously beating
• 70 beats \minute, 100,000 \ day
• pumps 1.5 million gallons of blood per year
• To prevent friction it is protected by a bursa
• Pericardium
• fibrous pericardium
• serous pericardium
• visceral peri. (epicardium)
• parietal peri.

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HEART I
Pericardial cavity lies between serous and
parietal pericardium. Contains approx. 10-20ml of
serous fluid Fibrous pericardium is continuous
superiorly with the adventitia of the great
vessels and anteriorly is attached to the sternum
by sternopericardial ligaments Base is attached
to central tendon of diaphragm
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HEART I

• Heart has four chambers divided by vertical
  septa.
• Right atrium and right ventricle
• Left atrium and left ventricle
• These terms (right and left) do not conform to
  the conventional right and left sides of the body.

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HEART I
Right atrium and right ventricle lie anterior to
the left atrium and ventricle. Form the anterior
anterior surface Right ventricle and left
ventricle form the inferior surface Left atrium
forms the base
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2 muscular pumps in parallel anatomically and in
series with each other
SVC
LA
PA
A
2
4
RA
3
1
RV
LV
IVC
1 tricuspid valve 2 pulmonary valve
3 bicuspid valve 4 aortic valve
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Tricuspid valve guards right atrioventricular
orifice anterior, septal and posterior
(inferior) cusps bases of cusps attached to
fibrous ring
s
A
P
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Tricuspid valve (cont.) chordae tendineae
connect free margins of cusps to papillary
muscles. papillary muscles are specialised
parts of the trabeculae carneae (cardiac muscle
in wall of ventricle
cusp
Chordae tendineae
Papillary muscle
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Tricuspid valve (cont.) chordae tendineae are
inelastic cords papillary muscles contract when
ventricles contract this holds chordae and
therefore cusps in place preventing ballooning
of cusps into right atrium
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Infundibulum funnel-shaped approach to
pulmonary trunk walls lack trabeculae carneae,
muscle replaced by fibrous and elastic
tissue fibrous ring give site for attachment of
the pulmonary valve pulmonary valve has 3
semilunar cusps
Anterior cusp Right cusp Left cusp
R
A
no chordae tendineae
L
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Pulmonary valve
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Left Side of the Heart atrium and ventricle
Left ventricle muscular wall is 3 times thicker
than right ventricle
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Biscuspid (mitral) valve guards left
atrioventricular orifice 2 cusps, anterior and
posterior cusps are smaller in area and thicker
than tricuspid valve chordae tendineae connect
free margins of cusps to papillary
muscles functions in a similar manner to
tricuspid.
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Biscuspid (mitral) valve
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Aortic valve 3 semilunar cusps, obliquely
oriented left, right and posterior cusps
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Right and left cononary arteries arise from the
aortic sinuses
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• Right Coronary Artery
• Marginal branch
• Posterior interventricular branch
• RCA supplies the right atrium, the right
  ventricle, interatrial septum, sinu-atrial and
  atrioventricular nodes

• Left Coronary Artery
• Circumflex branch
• Anterior interventricular branch
• LCA supplies most of the left atrium, left
  ventricle and interventricular septum (including
  atrioventricular bundle

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Cardiac veins All four major branches drain into
the coronary sinus
GREAT MIDDLE SMALL POSTERIOR
CARDIAC VEIN
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Anterior view
Postero-inferior view
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Conducting system of the heart modified cardiac
muscle cells Organised into nodes and networks
to relay electrophysiological impulses fibrous
skeleton electrically isolates atria from
ventricles Main parts sinu-atrial node (cardiac
pacemaker) atrioventricular node atrioventricula
r bundle and right left bundle branches
(moderator band on right side) purkinje fibres
(subendocardial plexus)
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