|Please note, that most of the
literature about the anatomy of cats is in English.
Some articles are based on experiments done with cats: We are
strictly against all animal experiments, which harm the animal. But,
even it is very tough to read such articles about animal experiments, they provide necessary
information to understand the cat's anatomy better.
The heart of the cat
||Click on the term to get a
What is Diastole and Systole?
The heart is a muscular hollow organ, whose
masculature (myocard) is covered by an outer skin (Epicard,
Pericard) and outlaid with a multi-level inner skin
(Endocard). The heart is separated into two
halves by the cardiac septum, the two halves work like pumps. These
pumps provide the blood circulation in its circulation system by the
automatic change between the contraction of the muscle (systole) and
dilatation of the muscle (diastole).
Contraction of atria
Contraction of chambers
The black arrows show the electrical pathway.
The red, thick arrows show the blood flow.
Sequence of heartbeats
- The sinoatrial node (SA-node) in the
right atrium works like a
small built-in timer. It fires off
an electrical impulse in regular intervals
(About 110-130 per minute when
the cat rests and
faster when the cat runs
fast. This controls the heart rate.)
Each impulse spreads across both atria which causes them to
contract. This pumps blood through the one-way
valves into the ventricles.
- The electrical impulse gets to the atrioventricular node (AV-node)
located at the lower right atrium.
The AV-node acts like a junction box and
the impulse is delayed slightly. Most of the tissue between the
atria and ventricles does not conduct the impulse.
But a thin band of conducting fibers,
called the atrioventricular bundle (AV-bundle),
acts like thin wires and carries the
impulse from the AV-node to the ventricles.
- The AV-bundle is
split into two branches - a right and
a left branch. These
branches then split into many tiny fibers (the Purkinje
system) which carry the electrical impulse throughout the
ventricles. Thus the ventricles contract
and pump blood through the one-way
valves into large arteries.
- The arteries coming from the right
ventricle take the blood to the lungs.
- The arteries coming from the left
ventricle take the blood to the rest of
- After the contraction the heart rests
for a short time (diastole). The blood
coming back to the heart from the large veins fills
the atria during the diastole.
- The veins coming into the left atrium come
from the lungs and their blood is full of
- The veins coming into the right atrium come
from the rest of the body and carry blood
depleted of oxygen.
This sequence is repeated during each heartbeat.
Closing of the valves causes a tone which can be heard by the
veterinary with the stethoscope.
The heartbeats normally match the pulse.
(beats = heart cycles /
||23 - 70
||60 - 70
||58 - 104
||100 - 130
||110 - 140
||123 - 304
||261 - 600
||260 - 400
||300 - 600