Download Heart 3: Valves

Heart 3: Valves
Heart 2. Chambers of the Heart
Blood flows through the heart in one direction: from atria to ventricles and out the great arteries
leaving the superior aspect of the heart. This one-way traffic is enforced by four valves that
open and close in response to differences in the blood pressure on their two sides.
Atrioventricular (AV) Valves
These valves prevent the backflow of blood into the atria during ventricular contraction/ systolic
phase of cardiac cycle.
The right atrioventricular (AV) valve has three cusps/flaps, therefore known as ‘tricuspid valve’,
while, the left AV valve has two cusps and known as Bicuspid valve or the Mitral valve.
The cusps/flaps of the valves are anchored to the papillary muscles with the help of fine
string-like structures, the chordae tendineae. This arrangement prevents the valves from being
everted or blown inside out into the atrium during contraction of ventricles.
This parasternal ultrasound shows a healthy mitral valve (bottom) and aortic valve (top) at
work. Can you figure out which is the atrium and which is the ventricle?
{mgmediabot2}path=http://anatomy2.mcmaster.ca/ultrasound_videos/normal_mitral_valve_son
ograph.flv|width=300|height=250{/mgmediabot2}
Aortic & Pulmonary (Semilunar) Valves
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Heart 3: Valves
The
two
entring
bases
the
of
aorta
the
also
and
two
have
pulmonary
great
valves.Blood
distributing
trunk.
from
vessels
(Pulmonary
has
tothe
trunk
pass
and
through
Aorta)
these
issuing
valves
from
before
the
Both
ofventricular
these pulmonary
like
aventricles
crescent
moon,
hence,
and
aortic
name
valves
semiventricles
have
lunar.
three
pocket-like
cusps,
each
shaped
roughly
during
These
semi
lunar
relaxation
valves
prevent
orthe
the
backflow
diastolic
of
filling
blood
phase
from
ofthe
great
cardiac
vessels
cycle.
into
the
ventricles
proceed to Heart 4. Fibrous Skeleton of the Heart
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