Transcript Circulatory system

THE CIRCULATORY
SYSTEM
Circulatory System
•Heart
•Veins
•Capillaries
•Arteries
Circulatory System
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•
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Heart
Veins
Capillaries
Arteries
Functions of the circulatory
system:
• Distribute nutrients
• Transport and exchange oxygen and
carbon dioxide
• Remove waste materials
• Distribute secretions of endocrine
glands
• Prevent excessive bleeding
• Prevent infection
• Regulate body temperature
Anatomy and Physiology
of the Heart
• Heart: funnel-shaped,
hollow, muscular organ that
is responsible for pumping
blood to all parts of the body.
–Pacemaker: special tissue
that controls the heartbeat
• The heart is located
near the center of
the thoracic cavity
between the lungs
and is contained in
the pericardial sac.
• Pericardial Sac:
supports the heart
and contains some
fluid for lubrication.
LAYERS OF THE HEART WALL
• Epicardium – outer
layer of heart wall
• Endocardium – inner
layer that consists of
endothelial cells, which
line the heart, covers the
heart valves, and lines
the blood vessels
• Myocardium – middle
layer composed of
cardiac muscle
Chambers of the heart
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Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
*Left and right sides
are separated by
the septum
Heart Valves
• Opens to allow
blood to go from one
chamber to another
chamber.
• Only lets blood flow
one direction
Heart Valves
• Pulmonary Valve:
from the R. Ventricle
to the lungs
• Aortic Valve: from
the left L. Ventricle
to the aorta
• Mitral/Tricuspid:
from the atria to the
ventricles
Veins & Arteries
• Upper/Lower Vena
Cava: brings blood to
the heart
• Pulmonary Vein:
brings blood from the
lungs to the heart
• Pulmonary Artery:
blood from heart to
lungs
• Aorta: blood from heart
to the body
– Largest vessel in our
body
VASCULAR SYSTEM
• The vascular system is made up of
three types of blood vessels:
– Arteries
– Capillaries
– Veins
Blood Vessels
Photo from U. S. Federal Government courtesy of Wikipedia.
ARTERIES
• BLOOD VESSELS
THAT CARRY BLOOD,
RICH IN OXYGEN,
FROM THE HEART TO
OTHER PARTS OF
THE BODY
– THICK WALLS
– ELASTIC TISSUE
– “A”RTERY = “A”WAY
from heart
– NARROW OPENING
ARTERIES
• Arteries branch
into smaller
vessels called
Arterioles
• Arterioles branch
into smaller
vessels called
Capillaries
CAPILLARIES
• Capillaries
– So small only one
blood cell wide
– This is where O2 ,
water, nutrients
and wastes are
exchanged
– Connects arteries
to veins
VEINS
• Blood vessels that
return blood to the
heart from all parts
of the body.
– Have thin walls
– Are collapsible
Capillary Bed
Interaction of molecules flowing in and out of blood at a capillary bed.
Parts of the
Circulatory System
The total circulatory system is
divided into two main parts:
• Pulmonary circulation, and
• Systemic circulation.
Pulmonary Circulation System
Red portion of heart and red blood vessels carry oxygen-rich blood.
Blue portion of heart and blue blood vessels carry oxygen-poor blood.
PULMONARY CIRCULATION
• Takes the blood from the heart to the
lungs, where it is oxygenated, and it
returns it to the heart.
SYSTEMIC CIRCULATION
• The flow of oxygenated blood from the
heart to the cells in all parts of the body,
and return of unoxygenated blood back
to the heart.
THE END
The Flow of Blood Through the
Systemic Circulatory System
Oxygenated blood
leaves the left
ventricle of the heart
through the aorta,
the largest artery in
the body.
The left and right coronary
arteries immediately branch from
the aorta and carry fresh blood to
the heart muscle itself.
The coronary veins quickly return
that blood back to the heart.
A heart attack often involves a
clot in the coronary arteries or their
branches.
In this illustration, a
clot is shown in the
location of #1. Area
#2 shows the portion
of the damaged heart
that is affected by
the clot.
Image by J. Heuser courtesy of Wikipedia.
The brachiocephalic trunk is the
next branch from the aorta.
The carotid arteries branch off
the brachiocephalic trunk and carry
oxygenated blood to the neck and
head region.
Blood from the neck and head
region returned by the jugular
veins.
The left and right brachial
arteries also branch from the
brachiocephalic trunk to supply
blood to the shoulders and forelegs.
The thoracic aorta refers to the
portion of the aorta that goes from
the heart, through the thoracic
cavity to the diaphragm.
The portion of the aorta that goes
from the diaphragm, through the
abdominal region, to the last
lumbar vertebrae is called the
abdominal aorta.
Branches from the thoracic aorta
supply oxygenated blood to the
lungs (via bronchial arteries),
esophagus, ribs and diaphragm.
The celiac artery branches from
the aorta immediately past the
diaphragm and itself branches into
the gastric, splenic, and hepatic
arteries.
The gastric artery supplies blood
to the stomach.
The splenic artery supplies blood
to the spleen.
The hepatic artery supplies blood
to the liver.
The cranial and caudal mesenteric
arteries branch from the abdominal
aorta and carry blood to the small
and large intestines.
The renal arteries are next to
branch from the abdominal aorta.
The renal arteries have two
important functions:
• supply blood to the kidneys, and
• carry large volumes of blood to
the kidneys for filtration and
purification.
From the renal arteries arise
arteries that supply blood to the
testicles in males (internal
spermatic arteries) and parts of
the reproductive system in females
(uteroovarian arteries).
The abdominal aorta ends where it
branches into the internal and
external iliac arteries.
The internal iliac artery supplies
blood to the pelvic and hip region.
The external iliac artery branches
into the femoral arteries.
The femoral arteries and their
branches supply oxygenated blood
to the hind legs.
Veins normally accompany arteries
and often have similar names.
Veins are always larger than the
arteries and are sometimes more
visible than arteries because they
are closer to the skin surface.
Most veins eventually empty the
un-oxygenated blood into the vena
cavas.
The cranial veins return the blood
from the head, neck, forelegs, and
part of the thoracic cavity to the
right atrium of the heart via the
superior vena cava.
These cranial veins include the
jugular vein, brachial veins,
internal thoracic veins, and the
vertebral veins.
The caudal veins return blood
from the iliac, lumbar, renal,
and adrenal veins to the right
atrium of the heart via the
inferior vena cava.
Before blood is returned to the
heart from the stomach, pancreas,
small intestine, and spleen, it goes
through the liver for filtration.
This portion of the systemic system
is known as the hepatic portal
system.
The gastric vein (stomach),
splenic vein (spleen), pancreatic
vein (pancreas), and mesenteric
veins (small intestines) empty into
the portal vein that carries the
blood to the liver.
In the liver, the portal vein branches
into smaller venules and finally into
capillary beds.
In the capillary beds of the liver,
nutrients are exchanged for storage
and the blood is purified.
The capillaries then join into venules
that empty into the hepatic vein,
which carries blood to the inferior
(caudal) vena cava.
Photo from Wikepedia.
Liver of a sheep: (1) right lobe, (2) left lobe, (3) caudate lobe, (4) quadrate
lobe, (5) hepatic artery and portal vein, (6) hepatic lymph nodes, (7) gall
bladder.
Anatomy and Physiology of
the Lymphatic System
The lymphatic system is part of
the immune system and acts as a
secondary (accessory) circulatory
system.
Functions of the lymphatic system:
• remove excess fluids from body
tissues,
• absorb fatty acid and transport
fat to circulatory system, and
• produce immune cells
(lymphocytes, monocytes,
and plasma cells).
Blood fluid escapes through the
thin-walled capillaries into spaces
between body tissue cells.
Lymph vessels, which have very
thin walls, pick up these fluids
called lymph.
Flow of Blood & Lymph Within Tissue
The lymph vessels join to form
larger ducts that pass through
lymph nodes (or glands).
Each lymph node has a fibrous
outer covering (capsule), a
cortex, and a medulla.
Photo from U. S. Federal Government courtesy of Wikipedia.
Lymph nodes filter foreign
substances, such as bacteria and
cancer cells, from the lymph before
it is re-entered into the blood
system through the larger veins.
Lymph nodes, which are scattered
among the lymph vessels, act as
the body’s first defense against
infection.
Lymph nodes produce the following
cells:
• Lymphocytes – a type of white
blood cell,
• Monocytes – a leukocyte that
protects against blood-borne
pathogens, and
• Plasma cells – produce antibodies.
Each lymph node has its own blood
supply and venous drainage.
The lymph nodes usually have names
that are related to their location in
the body.
When a specific location gets
infected, the lymph nodes in
that area will enlarge to fight
the infection.
If the lymph node closest to an
infected area is unable to
eliminate the infection, other
lymph nodes in the system will
attempt to fight the infection.
This is particularly critical in the
case of cancer, which can be
spread from its point of origin to
all parts of the body through the
lymphatic system.
Anatomy and Physiology
of the Blood
Blood is an important component
of the circulatory system.
Anatomically and functionally,
blood is a connective tissue.
The amount of blood that a
domestic animal has is expressed in
terms of percentage of body weight.
EXPECTED VOLUME OF BLOOD IN
DOMESTIC ANIMALS
Domestic Animal
% of Body Weight
Cattle
7.7 %
Sheep
8.0%
Horses
9.7%
Components of Blood
Plasma, which makes up 50 –
65% of the total volume of blood, is
a straw-colored liquid containing
water (90%) and solids (10%).
The solids in plasma include
inorganic salts and organic
substances such as antibodies,
hormones, vitamins, enzymes,
proteins, and glucose (blood sugar).
The non-plasma, or cellular, portion
of blood is composed of red blood
cells, white blood cells, and platelets.
From left to right:
Red blood cell
(erythrocyte);
Platelet
(thrombocyte);
White blood
cell (leukocyte).
Photo from U. S. Federal Government courtesy of Wikipedia.
Red blood cells, called erythrocytes,
are responsible for carrying oxygen
from the lungs to various body
tissues.
Red blood cells contain hemoglobin,
which gives them their characteristic
red color and helps them carry the
oxygen.
Red blood cells are biconcave discs, a
shape that provides a large area for
oxygen exchange.
Red blood cells are produced in the
red marrow of bones.
Most domestic animals have a red
blood cell count of seven million
cells per cubic millimeter of blood.
Red blood cells will last from 90 to
120 days and are removed from
the blood by the spleen, liver, bone
marrow, or lymph nodes when
they are worn out.
Anemia is a condition caused by low
levels of red blood cells and
hemoglobin.
Anemia can be caused by the following:
• Loss of blood due to injury,
• Infestations of blood-sucking
parasites, or
• Low levels of red cell production due
to poor nutrition.
Hemoconcentration is a
condition in which there is an above
normal level of red blood cells.
Hemoconcentration is normally
caused by dehydration (loss of body
fluid), which can be the result of
vomiting, diarrhea, or any chronic
disease characterized by high body
temperatures.
Blood platelets, or thrombocytes,
are oval-shaped discs that are
formed in the bone marrow.
Blood platelets help prevent blood
loss from injuries to blood vessels
by forming clots (white thrombus).
Platelets may secrete a substance
that causes the clot to contract
and solidify.
Platelets may also secrete a
substance that causes an injured
vessel to constrict at the injury.
White blood cells, or leukocytes, are
divided into two general categories:
• Granulocytes, and
• Agranulocytes.
Granulocytes are the category of
leukocytes that contain granules
within the cytoplasm.
Granulocytes include:
• Neutrophils,
• Eosinophils, and
• Basophils.
Neutrophils – produced by bone
marrow, neutrophils fight disease by
migrating to the point of infection,
absorbing bacteria, and destroying
them.
Neutrophil (purple) migrating through tissue
to engulf bacteria through phagocytosis.
Neutrophils dissolve
dead tissue resulting
in a semi-liquid
material called pus.
Courtesy of Wikipedia.
Abscess – a concentrated area of pus.
Eosinophils - a type of granulocyte
that plays a role in combating
infection by parasites, as well as,
impacting allergies and asthma.
They contain most
of the histamine
protein in the blood,
which is an
indication of allergic
reaction when elevated.
Images courtesy of Wikipedia.
Basophils – rare granulocytes that
are responsible for the symptoms
of allergies, including inflammation.
Basophils
Image courtesy of Wikipedia.
Agranulocytes are the category
of leukocytes that contain very
little, if any, granules.
Agranulocytes are produced by
the lymph nodes, spleen, thymus,
and other lymphoid tissue.
There are two types of agranulocytes:
• Lymphocytes, and
• Monocytes.
Lymphocytes – agranulocytes that
produce and release antibodies at
site of infections to fight disease.
Lymphocytes also
produce antibodies
that allow an animal
to build up immunities
to a particular disease.
Image from U. S. Federal Government courtesy of Wikipedia.
Monocytes are agranulocytes that
absorb disease-producing materials,
such as bacteria that cause
tuberculosis, through phagocytosis.
Unlike neutrophils,
monocytes do not
produce pus.
Image courtesy of Wikipedia.
Monocytes join body tissue to form
larger, disease-absorbing masses
called macrophages.
In domestic animals, approximately
85% to 90% of the leukocytes in
domestic mammals are neutrophils
and lymphocytes.
The total number of neutrophils and
lymphocytes are about equal, but
temporary stress increases the ratio
of neutrophils to lymphocytes until
that stress is removed.
When bacterial infections occur,
the number of white blood cells
normally increases.
When viral infections occur, the
number of white blood cells
normally decreases.
Therefore, the concentration of
white blood cells can help
diagnose disease.
Blood clotting is called
coagulation and is important in
reducing blood loss caused by
injury and in healing the injury.
Fibrin is a thread-like mass
produced by fibrinogen (fibrous
protein in blood) and thrombin.
Fibrin holds the red blood cells,
white blood cells, and platelets
together to form a blood clot.
White Cell Counts and Coagulation
Times for Domestic Animals
Species
Normal White Cell Count
Coagulation Time
( Per Cubic Millimeter)
Cattle
9,000
6 ½ Minutes
Swine
15,000
3 ½ Minutes
Sheep
8,000
2 ½ Minutes
Horses
9,000
11 ½ Minutes
Vitamin K helps maintain
Antithromboplastin and
antithrombin, which are two
substances that prevent blood
from clotting within the
circulatory system.
Blood types are classified based on
certain antigens and antibodies
found on surface of red blood cells.
For example, in humans there are a
total of 29 blood group systems based
on antigens on the surface of the red
blood cells, but the ABO and Rhesus
factor (positive or negative) are the
commonly used groups to determine
blood type.
Human ABO Blood Types
Image courtesy of Wikipedia.
Young animals can receive certain
antibodies from their mothers.
These antibodies must be passed
on to the young animal through
the colostrum milk because the
placental membrane is fairly
impermeable.
When two different blood types, an
antigen and its antibody, combine
as a result of mating, the reaction
would cause agglutination or the
clumping together of red blood
cells.
This may cause some deaths
during the early embryonic
development in animals.
Many blood types and groups have
been identified in domestic animals.
• Cattle have 9 recognized blood
groups;
• Horses have 8 recognized blood
groups; and
• Canine have 13 described groups,
but only 8 recognized groups.
Some blood types can cause disease
in the offspring of animals.
Individual animals and their parents
can be identified using blood-typing.
Bulls used for commercial artificial
insemination must be blood-typed.
Certain blood types may be
connected to superior production
and/or performance in animals.
For example, egg production and
hatchability can be improved in
chickens and Pork Stress Syndrome
(PSS) can be identified in swine.
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Texas A&M University
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2007