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Blood is made up of about
60% liquid (plasma) and
40% formed elements which
consist of erythrocytes (red
blood cells) leukocytes
(white blood cells) and
thrombocytes (platelets)
Blood :
*transports oxygen from the lungs
*collects waste products and
delivers it to the excretory organs
for disposal
*carries hormones from ductles
glands
*maintains fluid content of the
tissue
*regulates temperature
Blood is about 5 times as
viscous as water and the color
varies from bright red to dark
purple depending on the
oxygen content.
Plasma:
This liquid portion of the blood is straw
colored and is approximately 90% water
and 10% solutes. Protein makes up the
majority of the solutes. One of these
proteins is fibrinogen which is important for
blood clotting
If the clotting factors are
removed the resulting liquid is
called serum
Blood cells:
all blood cells begin as stem cells,
which are undifferentiated cells.
In young animals blood cells are
produced in all bone marrow. In
adults blood cells are produced in
red bone marrow
Proerythrocytes=erythrocytes
myeloblasts=granulocytes
lymphoblasts=lymphocytes
monoblasts=monocytes
megakaryoblasts=thrombocytes
Erythrocytes are non-nucleated
biconcave disks that carry hemoglobin.
This iron containing pigment combines
with oxygen and gives blood the red
color. Hemoglobin not only combines
with oxygen in the lungs to carry it
throughout the body but also combines
with carbon dioxide and carries it to the
lungs for disposal
The average life span of
erythrocytes is 120 days but can
vary. If iron is lacking then the
hemoglobin is reduced as well as
the total number of erythrocytes
resulting in a decreased ability to
carry oxygen and waste
Leukocytes:
Everybody say “yeah for
leukocytes!!!!!!”
There are five types of leukocytes
and they are divided into two
groups:
Granulocytes
Agranulocytes
Granulocytes: these originate in
the bone marrow and contain
fine granules. These are further
classified based on staining
characteristics.
Segmented neutrophils:
These cells are the first line of defense and
phagocytize invaders as well as build a wall against
invaders
Eosinophils:
These detoxify foreign proteins from allergens or
parasitic infections.
Basophils:
These have purple to blue staining granules. There
function isn’t clear but they may prevent coagulation
in blood vessels
Agranulocytes:
“yeah agranulocyte, do the wave
for agranulocyte!!
These cells originate in the lymph
system and have a round or
horseshoe shaped nucleus
Lymphocyte:
These have a rounded nucleus and function in
phagocytosis and immune response.
Monocytes:
these have a horseshoe shaped nucleus and function
primarily as phagocytes
Platelets (thrombocytes)
these cells originate in the bone
marrow and function in the
clotting mechanism. Clotting is
a result of a chemical reaction.
Platelets attach to an injured
blood vessel and release
substances that contract blood
vessels.
Blood is grouped into types
named for the antigens found on
the cell membranes. The
purpose of matching is to find a
match before giving blood
transfusions.
Rh factor: a protein on the
surface of red blood cells.
In some animals there is a
reaction of antibodies from the
dam. These animals exhibit
destruction of erythrocytes.
Blood pressure:
this is the force exerted by the heart in
pumping the blood through the blood
vessels.
Systolic pressure is produced by the
blood pressing against the walls of the
arteries during contraction of the
ventricles and diastolic is pressure is
produced against the artery walls during
ventricular relaxation
The difference between the systolic and
diastolic pressure is called the pulse
pressure. Diastolic is considered more
important medically because it shows
the least amount of pressure to the
artery walls. An elevation in blood
pressure is called hypertension and a
low blood pressure is called
hypotension
The pulse:
This is produced by the blood pumping out of
the heart and into the aorta. This increases
and decreases the pressure on the walls of the
aorta which expands as blood enters and
relaxes as it leaves.
Tech tip.. Never take a pulse with your thumb
as it already has a pulse of it’s own.
Circulation:
systemic circulation:
blood circulating from the left
ventricle to aorta, arteries,
arterioles, capillaries, vemules,
veins and returning to the right
atrium
Portal circulation:
The circuit through the
abdominal digestive organs.
Blood from veins and organs is
carried to the liver via the portal
vein. The hepatic veins carry
the blood to the caudle vena
cava, back to the right atrium
Pulmonary circulation:
blood enters the right atrium to
right ventricle to pulmonary
artery which has two branches,
one branch for each lung. Blood
is oxygenated and returned to the
left atrium and ventricle via the
pulmonary vein.
It takes about one minute for the
blood to make a complete cycle.
The aorta is the largest artery in
the body. The aorta branches
into other arteries that supply
blood to all of the systems
Right and left common
carotid arteries.
These supply the right and
left side of the head
The external iliac arteries
branch to the femoral arteries.
These supply blood to the hind
legs and are used for taking an
animal’s pulse
Superficial veins include the
internal and external jugular
veins. The external jugular
vein is commonly used for
venapuncture
The saphenous vein drains into
the femoral vein and returns
blood from the hindlegs. The
saphenous vein is commonly
used for venapuncture in felines
The lymphatic system:
This system is made of fluid called
lymph. Lymph is rich in white
blood cells and is circulated
through the body by the lymphatic
system.
The lymph glands are enclosed fibrous capsules.
They are identified by their location. Superficial
nodes are palpable (submandibular, axillary,
popliteal, inguinal)
The lymph nodes act as filters to
remove bacteria and other foreign
bodies, including malignant cells. They
are seen or felt when they are inflamed
or swollen by ingested bacteria.
If they are swollen and painful: an acute
reaction is indicated
If they swollen, lobulated and not
painful:
a chronic reaction is indicated
Another important function of the lymph glands
is to manufacture lymphocytes and monocytes..
The lymphatic system is very important for the
body’s defense against infection
The Spleen:
The spleen is a large, flattened glandlike organ
located on the left side of the abdominal cavity. It is
the largest structure in the lymphoid system.
It’s functions include:
Hemopoiesis:
The formation of lymphocytes,
monocytes and plasma cells.
Phagocytosis:
The removal and destruction of
microorganisms, faulty platelets,
and old erythrocytes. It also
salvages the contents of
destroyed erythrocytes to reuse.
The Tonsils:
These are three pairs of small round masses of
lymphoid tissue that filter out foreign bacteria and
play a part in forming lymphocytes.
The palatine: located in the back of the throat
The lingual: located at the root of the tongue
The pharyngeal: located at the back of the roof of the
pharynx
The Thymus:
This is a structure of lymph tissue located cranial to the heart.
It plays an important role in the immune system by producing
cells that destroy foreign substances and forming lymphocytes.
It’s maximum development is in young animals. It then begins
to atrophy and has almost disappeared by extreme old age