*230,24
The three-chambered heart of the frog
sits between the left and right lobes
of the liver.
>S(11),236,231
*231,24
It's connected to three veins and one
large artery.
>S(11),236,232
*232,24
The heart muscle is the pump for the
frog's circulatory system.
>S(11),236,233
*233,24
The beating heart sends blood out
through the arteries and brings it back
through the veins.
>B(10),236,0
>E(11),236,234
*234,24
A frog's circulatory system is much
like that of more complex vertebrates.
>E(11),236,235
*235,24
But there are significant differences,
such as the structure of the heart.
>E(10),236,0
*236,34
Human hearts (four chambers) are more
complex than a frog's (three chambers).
>S(21),240,237
*237,34
With only three chambers, a frog's
heart must mix oxygenated and
non-oxygenated blood.
>B(20),240,0
>E(21),240,238
*238,34
Frogs are cold-blooded, humans are
warm-blooded.
>E(21),240,239
*239,34
As a result, the rate of a frog's
heartbeat is much more dependent on the
outside temperature.
>E(20),240,0
*240,44
Blood without oxygen pours into the
right atrium. Blood with oxygen--from
the lungs--flows into the left atrium.
>S(01),0,241
*241,44
Both bloods mix in the ventricle,
which pumps the blood out.
>S(00),0,0
*1000