Transcript The heart is protected by rib cage

The mammalian heart
Heart
• locate between two
lungs
• made of cardiac
muscle
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• protected by
pericardium and rib
cage
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Heart – External View
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Coronary
artery
and vein
CardiacMuscle
Vertical section of the Heart
Semi-lunar valves
Pulmonary artery
Arteries
To lungs
Aorta
To body
Pulmonary
Veinsveins
Vena Veins
cava
Left
auricle
bicuspid
valve
Right
auricle
tricuspid valve
septum
Left
Right
ventricle
ventricle
Valve – deoxygenated
prevent back flow of
blood from
blood
……………… toblood
……………..
oxygenated
Oxygenated
blood
Higher oxygen
concentration
Full of Oxygen 
Lower carbon
dioxide
concentration
Deoxygenated
blood
Lower oxygen
concentration
Full of carbon dioxide 
Higher carbon
dioxide
concentration
The cardiac cycle (the sequence of events
that takes place in one
heart beat)
The heart beats as the cardiac
muscles in its wall contracts
(systole) and relaxes (diastole).
Auricle
Ventricle
0
0.2
0.4
0.6
0.8s
Auricle
Ventricle
0
0.2
0.4
0.6
0.8s
 Auricular systole (0 –0.1s)
contraction of the two auricles,
squeezing blood into the ventricles
AV valves (open), semi-lunar valves (close)
Auricle
Ventricle
0
0.2
0.4
0.6
0.8s
 Ventricular systole (0.1 –0.4s)
contraction of the two ventricles,
forcing blood out of the ventricles into the
arteries
AV valves (close), semi-lunar valves (open)
Auricle
Ventricle
0
0.2
0.4
0.6
0.8s
 Diastole ( 0.4 - 0.8s )
all four chambers relax, allowing
blood to flow into the auricles again.
AV valves (open), semi-lunar valves (close)
Changes in blood pressure in the heart during
one cardiac cycle.
Heart beat rate
=
P(V) > P (A)
60 / 0.8 = 75 beats / min
P(V) < P (A)
bicuspid
valve
close
bicuspid
valve open
1st heat
sound
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