 The




CVS includes
Heart
Blood vessels
Blood
Blood circulation
 The
heart is a hollow, cone shaped muscular
organ.

Pump that circulates the blood throughout the
body to nourish and to remove waste products
from the tissues.
 The
heart is divided into 4 chambers
 The size of the heart depends upon species
and the overall size of the animal.

Blue whale has a heart that weighs 1,000 pounds

Whale weighs 120 tons
 The
heart is covered by a saclike membrane,
consists of three layers

Pericardium


Parietal


Tough, fibrous external layer
Lines the pericardium
Epicardium

Covers the surface of the heart
 The
heart is divided into a left and a right
side. The hollow of the heart is divided into
four chambers.
 Each cranial chamber is called an atrium.

A wall called the interatrial septum divides the
atria into the right and left sides
 Each

ventral chamber is called a ventricle.
A wall called the interventricular septum divides
the ventricles into right and left sides
 The
atria have thin walls and are the
receiving chambers.
 The right side of the heart receives blood
from body tissues and sends it to the lungs to
be oxygenated.
 The left side of the heart receives
oxygenated blood from the lungs and sends it
to the tissues.
 Blood
flow animation
 The
ventricles have thicker walls than the
atria.

They are responsible for the pumping
 The
left ventricles wall is thicker than the
right however.


Left – pumps blood to all the blood vessels of the
body
Right – lungs only
 Between
the atria and
the ventricles are
valves.

Atrioventricular valves

Close to ensure that the
blood flows in one direct
and to prevent backflow of
blood into the atria.

The heart is a double
pump - and both sides
are doing much the
same thing, it's just
that their targets are
different - the left
side of the heart, full
of oxygenated blood,
is sending blood out to
the body; the right
side of the heart has
just received its blood
from the body, and is
sending it out to the
lungs.
 The
cardiac cycle includes the contraction
(systole) and relaxation (diastole) of the
atria and the ventricles.

The four heart chambers do not contract all at
on time.

The two atria contract in unison, and as they
relax, the two ventricles contract.
 Animals
have three major types of blood
vessels

Arteries


Capillaries


Elastic tubes with thick walls
Minute, very thin-walled vessels that distribute blood
to the tissues
Veins

Hollow tubes, similar to the arteries, with thinner and
less elastic walls.

Arteries are pipelines that
generally carry blood away
from the heart. They carry
oxygen-rich blood. They are
usually designated by the
color red because oxygenrich blood is red.
 Veins
generally carry
oxygen-poor blood back to
the heart from the rest of
the body. They are usually
designated by the color blue
because oxygen-poor blood
is a darker color.

Capillaries are
microscopic blood vessels
that connect arteries to
veins.

They are where oxygen &
waste exchange occur.

They are only big enough
for one blood cell to pass
at a time.
Click here for a video of blood flowing
in the blood vessels
The Capillaries are in between the artery
on the left and the vein on the right
The little donut-shaped red blood cell
(scientific name erythrocyte) squeezes
through the capillary and drops off its
cargo of nutrients and oxygen
 This
is the path of the blood through the heart,
lungs, and body.
Click here for a silly
circulation song!
Follow the arrows in the
pictures to trace the flow of
blood through the heart,
lungs and body.
 The
tough, fibrous external layer of
membrane covering the heart is called
__________. The outer surface of the heart
itself is covered with a layer called the
__________.
 The two thin walled receiving chambers of
the heart are _________. The thicker walled
chambers into which they feed are called
_________.
 Pericardium
 Epicardium
 Atria
 Ventricles
 Blood
is made up of about 60% plasma
(liquid), and 40% formed elements, which
consist of erythrocytes (red cells), leukocytes
(white cells) and thrombocytes (platelets).
 Blood







Transports oxygen
Collects carbon dioxide
Distributes nutrients
Collects waste products of metabolism
Carries hormones
Maintains fluid contents of the tissues
Serves as a temperature regulator
 The
average amount of blood contained in a
adult animal varies by species.


Typically denoted as a % of body weight
Depending on the species, blood makes up 6% 8% of total body weight.
 Plasma

is 90% water and 10% solutes.
Solutes





Most are proteins (albumin, fibrinogen, globulins)
Nutrients
End products of metabolism
Gases
Hormones
 Blood
proteins can be divided up into 3
categories.

Albumin


Globulins


Maintains water in the bloodstream. Draws water into
the blood vessel through osmosis. Albumin is produced
by the liver.
Antibodies produced to fight disease. Globulins are
produced by the immune system.
Fibrinogen

Aids in clotting blood. When a blood vessel is
damaged, the fibrinogen is converted to fibrin.
 Erythrocytes






(red blood cells)
At maturity, erythrocytes are extremely small,
nonnucleated disks.
Contain hemoglobin – an iron containing pigment
Carry oxygen to body cells
Lack or reduction of iron – anemia
Produced in the bone marrow (erythropoiesis)
Average life span is 120 days in dogs
 Leukocytes




(white blood cells)
Much less numerous than erythrocytes
Colorless
Have nuclei
5 major types of leukocytes





Neutrophils- function as phagocytosis (ingest through
endocytosis) to destroy invading microorganisms
Lymphocytes- function in phagocytosis and antibody
formation
Eosinophils- detoxify foreign proteins from allergens
or parasitic infections
Monocytes- have a horseshoe shaped nucleus and
function mainly in phagocytosis
Basophils – fight allergic reactions
 Thrombocytes
(platelets) originate in red
bone marrow. They function in the clotting
mechanism.
 Fibrinogen and prothrombin convert to fibrin
and thrombin. The two work together to
form a mesh for the blood to form a clot on.
If clotting factors are not present, the
resulting liquid is called serum.
 The
liquid portion of blood is called ______.
If the clotting elements are removed it is
called __________.
 Blood makes up ______% to ______% of an
animals total body weight.
 The scientific name for red blood cells is
__________, and for white blood cells it is
__________.
 Blood platelets are also called ________.
 The
liquid portion of blood is called PLASMA.
If the clotting elements are removed it is
called SERUM.
 Blood makes up 6% to 8% of an animals total
body weight.
 The scientific name for red blood cells is
ERYTHROCYTES, and for white blood cells it
is LEUKOCYTES.
 Blood platelets are also called
THROMBOCYTES.
 The
aorta, the largest artery in the body,
originates from the left ventricle of the
heart. The aorta arches dorsally then travels
caudally. It branches into other arteries that
supply the head, neck, thoracic limbs, chest,
and abdomen, finally dividing into arteries
that supply the pelvic limbs.
 Coronary
arteries – supply blood to the heart
 Brachiocephalic artery – 3 large branches



Right subclavian artery – supplying the right
thoracic limb
Right common carotid – supplying the right side
of the head
Left common carotid – supplying the left side of
the head
 Left
subclavian artery – supplying the left
thoracic limb.
 Celiac
artery – supplying the liver, stomach,
and spleen
 Cranial mesenteric artery – supplying the
small intestine
 Renal arteries – supplying the kidneys
 Ovarian (or testicular) arteries – supplying
the structures for which they are named
 Caudal mesenteric artery – supplying the
large intestine
A
rhythm is the recurrence of an action or
function at regular intervals.

For the heart, the rhythm it keeps is called
heartbeat
 The
heartbeat is modified by electrical
impulses from nerves that stimulate the
myocardium.

Sinoatrial node (SA)
 The
SA is located in the wall of the right
atrium near the entrance of the superior
vena cava.
 The
SA node works with Purkinje fibers to
establish the basic rhythm of the heart.


Purkinje fibers are less developed in the atria
and are usually associated with the ventricles.
The Purkinje fibers connect the SA with the
atrioventricular node (AV)
 The
AV node is found close to the junction
between the atrium and the ventricle. It
sends the electrical impulse to the
ventricles.
 An
electrocardiograph can pick up the
electrical impulses and provide a print out of
the heart rhythm.

electrocardiogram
 Cardiac
Cycle
Normal rhythm, but
heartbeat is faster than
normal.
Normal rhythm, but
heartbeat is slower
than normal.
Heart rate increases with
inspiration and decreases
with expiration
SA node is not working.
Heartbeat is irregular
and rapid
No regular rhythm,
ventricles quiver
uncontrollably.
Cardiac arrest. The
heart is not beating.
 Veterinarians
evaluate many things when
listening to the heart.

Heart rate

Heart rhythm

Listen for murmurs or abnormal flow of blood



The rate and regularity of the heart rhythm is termed
the heartbeat
The heartbeat is influenced by the electrical impulses
from nerves that stimulate the myocardium
Cardiac output is the volume of blood pumped by the
heart per unit time
Copyright © 2006 Thomson Delmar Learning
Auscultation is listening
to body sounds with a
stethoscope
 When auscultating the
heart, a lubb/dubb sound
is heard




lubb = closing of the
atrioventricular valves
dubb = closing of the
semilunar valves
murmur = abnormal sound
associated with turbulent
blood flow
Copyright © 2006 Thomson Delmar Learning
 Blood
pressure is the tension exerted by
blood on the arterial walls

The combining form for pressure or tension is
tensi/o
A
pulse is the rhythmic expansion and
contraction of an artery produced by
pressure
 Blood pressure is measured by a
sphygmomanometer
Copyright © 2006 Thomson
Delmar Learning