Cardiovascular System-Heart: PPT + Notes

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3. -­‐
the
heart
is
located
in
the
mediasBnum
of
the
thoracic
cavity
-­‐
the
heart
is
approximately
the
size
of
your
fist
and
lies
between
the
lungs
and
superior
to
the
diaphragm
-­‐
the
heart
is
protected
by
the
vertebral
column
posteriorly
and
the
sternum
anteriorly
-­‐
the
heart
is
surrounded
by
the
pericardium,
which
forms
a
protecBve
sac
around
it
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Thoracic
Cavity

4. -­‐
atria
are
the
smaller
superior
chambers
-­‐
ventricles
are
larger
inferior
chambers
-­‐
oxygenated
blood
is
supplied
to
the
heart
muscle
by
coronary
arteries,
which
are
branches
of
the
aorta
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Heart
Chambers
-­‐
the
heart
consists
of
four
chambers
that
are
visible
both
externally
and
internally:
-­‐
right
atrium
-­‐
right
ventricle
-­‐
leJ
atrium
-­‐
leJ
ventricle

5. -­‐
great
vessels
are
associated
with
one
of
the
chambers
of
the
heart
-­‐
they
either
deliver
blood
to
an
atrium
or
receive
blood
pumped
out
of
a
ventricle
-­‐
the
excepBon
is
the
pulmonary
arteries;
they
receive
blood
from
the
pulmonary
trunk
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Great
Vessels
-­‐
great
vessels
(with
the
excepBon
of
the
pulmonary
arteries)
are
aPached
to
the
base
of
the
heart.
They
include:
-­‐
inferior
vena
cava
-­‐
superior
vena
cava
-­‐
pulmonary
trunk
-­‐
pulmonary
arteries
-­‐
pulmonary
veins
-­‐
aorta

6. -­‐
heart
muscle
does
not
receive
its
oxygen
and
nutrients
from
the
blood
passing
through
its
chambers,
but
relies
on
the
coronary
circulaBon
-­‐
right
and
leJ
coronary
arteries
are
branches
of
the
aorta
that
arise
just
above
the
aorBc
valve
-­‐
each
curves
down
to
supply
oxygen
and
nutrients
to
the
heart
muscle.
Deoxygenated
blood
is
collected
by
the
coronary
veins
and
is
returned
directly
to
the
right
atrium
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Coronary
CirculaBon

7. -­‐
atria
have
a
thin
muscular
wall
-­‐
primary
funcBon
is
to
collect
blood
returning
to
the
heart
and
then
contract
to
deliver
it
to
the
ventricles
-­‐
the
ventricles
are
much
larger-­‐volumed
chambers
and
have
a
very
thick
wall
-­‐
they
are
the
primary
pumping
chambers
-­‐
because
the
leJ
ventricle
must
push
blood
a
greater
distance,
it
has
the
thickest,
most
muscular
wall
-­‐
atria
communicate
with
ventricles,
but
the
right
and
leJ
halves
of
the
heart
are
completely
separated
from
each
other
by
a
muscular
wall,
the
septum
-­‐
for
this
reason,
it
is
able
to
funcBon
as
a
double
pump
-­‐
each
half
pumps
blood
into
a
different
circuit.
The
right
side
of
the
heart
receives
deoxygenated
blood
from
the
body
and
pumps
it
to
the
lungs
for
oxygenaBon,
the
pulmonary
circulaBon
-­‐
the
leJ
side
of
the
heart
receives
oxygenated
blood
from
the
lungs
and
pumps
it
to
the
body,
the
systemic
circulaBon
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Heart
Chambers

8. -­‐
lub
is
caused
by
the
closing
of
the
atrioventricular
valves
and
dub
is
caused
by
the
closing
of
the
semilunar
valves
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Heart
Valves
-­‐
the
heart
has
four
valves
composed
of
strong
fibrous
Bssue
flaps
called
cusps,
which
close
to
prevent
regurgitaBon
(backflow)
of
blood
-­‐
this
ensures
that
blood
flows
only
in
a
forward
direcBon
through
the
heart
-­‐
one
pair
of
valves
atrioventricular
valves
(tricuspid
valve
on
the
right
and
mitral
valve
[or
bicuspid
valve]
on
the
leJ),
are
found
between
the
atria
and
ventricles
-­‐
they
prevent
blood
in
the
ventricles
from
flowing
back
into
the
atria
when
the
ventricles
contract
-­‐
the
second
pair
of
valves,
the
semilunar
valves
(pulmonary
valve
on
the
right
side
and
aorBc
valve
on
the
leJ),
are
found
between
the
ventricles
and
the
great
arteries
-­‐
they
prevent
blood
that
has
just
been
ejected
into
the
great
arteries
from
flowing
back
into
the
ventricles
when
the
ventricles
relax
-­‐
the
two
audible
heart
sounds,
“lub”
and
“dub"
(or
"dup"),
occur
as
these
valves
close

9. -­‐
endocardium
-­‐
myocardium
-­‐
epicardium
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Heart
Wall
-­‐
the
wall
of
the
heart
is
composed
of
three
layers:

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The
ConducBon
System
-­‐
in
order
to
pump
blood,
the
chambers
of
the
heart
alternate
between
a
relaxaBon
phase,
called
diastole,
and
a
contracBon
phase,
called
systole
-­‐
one
complete
round
of
diastole
and
systole
is
called
the
cardiac
cycle
(it
is
also
one
heartbeat)
-­‐
when
a
chamber
is
in
diastole,
blood
is
able
to
flow
into
the
chamber
because
it
is
relaxed
-­‐
during
systole,
the
chamber
contracts,
developing
the
force
needed
to
squeeze,
or
eject,
blood
from
the
chambers
-­‐
the
heart
valves
open
and
close
to
ensure
that
blood
only
flows
forward
through
the
heart
and
not
backward
(called
regurgitaBon)
-­‐
in
order
to
work
effecBvely
as
a
pump,
the
heart
muscle
must
contract
the
chambers
in
a
specific
paPern
-­‐
the
heart's
effecBveness
is
reduced
if
the
ventricles
contract
before
the
atria
finish
delivering
blood
to
them
-­‐
to
accomplish
this
task,
the
heart
has
a
network
of
interconnected,
specialized
cardiac
muscle
cells
called
the
conducBon
system
that
is
able
to
sBmulate
a
heartbeat
-­‐
as
the
wave
of
sBmulaBon
spreads
through
the
conducBon
system,
the
chambers
of
the
heart
are
sBmulated
to
contract
in
the
proper
sequence
-­‐
it
is
important
to
note
that
while
the
heart
is
divided
into
leJ
and
right
halves
for
blood
flow,
the
conducBon
system
moves
from
the
top
to
the
boPom;
meaning
that
both
atria
contract
together,
then
both
ventricles
contract
together
-­‐
the
heart
is
unique
in
that
it
does
not
require
the
nervous
system
to
sBmulate
contracBon,
it
is
responsible
for
sBmulaBng
itself
to
contract
-­‐
the
nervous
system
does
play
a
role
in
adjusBng
the
rate
at
which
the
heart
contracts

11. -­‐
because
large
regions
of
the
heart
muscle
are
sBmulated
and
contract
simultaneously,
their
electrical
acBvity
can
be
detected
and
recorded
by
a
machine
called
an
electrocardiograph
-­‐
the
tracing
of
the
electrical
current
is
called
an
electrocardiogram
(ECG)
and
shows
the
changes
in
electrical
voltage
over
Bme.
It
is
interesBng
to
note
that
electrocardiogram
may
also
be
abbreviated
as
EKG
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QRS
Complex