The
amount
of
monitoring
and
adjusting
that
goes
on
in
the
human
body
at
any
given
time
is
astounding
.
Thankfully
,
it's
____________________
,
so
you
never
have
to
think
about
it
.
Every
change
in
activity
requires
you
to
make
____________________
in
respiration
,
or
heart
rate
,
or
energy
delivery
,
and
an
adjustment
to
one
system
often
changes
the
balance
in
some
other
system
.
Heart
rate
is
controlled
by
a
____________________
.
This
item
that
controls
your
heart
rate
is
found
within
the
____________________
.
When
you
____________________
and
need
to
pump
more
blood
.
When
you
____________________
you
need
to
pump
less
blood
.
The
pacemaker
within
your
heart
is
told
to
speed
up
or
slow
down
because
of
signals
sent
by
the
____________________
.
____________________
is
the
pressure
that
blood
exerts
on
the
walls
of
the
blood
vessels
.
The
brain
can
alter
the
diameter
of
the
____________________
by
making
them
wider
or
narrower
.
The
____________________
system
exchanges
oxygen
with
carbon
dioxide
between
the
bloodstream
and
the
air
.
This
is
controlled
by
the
brain
.
You
____________________
kill
yourself
by
holding
your
brain
.
There
are
many
ways
that
your
body
controls
temperature
.
Heat
from
within
your
body
is
released
with
each
____________________
out
.
But
,
when
you
get
really
hot
we
____________________
.
During
strenuous
activity
your
body
____________________
release
as
much
as
1
.
5
Liters
of
sweat
every
hour
.
Sugar
is
carried
by
the
____________________
in
our
bodies
to
different
parts
within
us
like
our
hands
and
feet
.
Insulin
lowers
the
amount
of
____________________
in
this
item
that
carries
our
sugar
.
Glucagen
raises
the
amount
of
sugar
.
EXERCISE
____________________
the
amount
of
blood
sugar
levels
.
