Download Vasculature and Lymphatics

Vasculature and Lymphatics
Student Learning Objectives:
•
•
•
Identify the primary blood vessels of the body.
Follow the blood through the path of the circulation.
Identify the major structures of the lymphatic system.
Structures to be studied:
Vessels:
Aorta
Pulmonary artery
Superior vena cava
Inferior vena cava
Pulmonary veins
Brachiocephalic artery
and vein
Common carotid artery
Internal carotid artery
Eternal carotid artery
Facial artery and vein
Maxillary artery and vein
Jugular veins
Subclavian artery and vein
Axillary artery and vein
Brachial artery and vein
Radial artery and vein
Ulnar artery and vein
Basilic vein
Cephalic vein
Accessory cephalic vein
Median cubital vein
Celiac artery (trunk)
Superior mesenteric artery
Renal artery and vein
Gonadal artery and vein
Inferior mesenteric artery
Hepatic-portal vein
Common iliac artery and vein
Internal iliac artery and vein
External iliac artery and vein
Femoral artery and vein
Popliteal artery and vein
Anterior tibial artery and vein
Posterior tibial artery and vein
Great saphenous vein
Lymphatic Structures:
Lymphatic vessels
Lymph nodes
Tonsils
Pharyngeal
Palatine
Lingual
Spleen
Thymus
Introduction
The vasculature consists of numerous blood vessels that provide the tubing through
which the blood travels around the body. Arteries are the vessels that transport blood
away from the heart. Such vessels typically transport highly oxygenated blood. The
pulmonary arteries, however, carry blood with a low level of oxygen. Arterioles branch
off of the arteries and help distribute the blood within an organ. Tiny capillaries serve as
the exchange sites between blood and tissues. The venules connect the capillaries to the
veins that transport blood back to the heart. Veins typically carry low oxygen blood (i.e.
deoxygenated blood), again with the exception of the pulmonary veins.
The arteries and arterioles have a very thick muscular wall. They help ensure that the
blood will arrive at the tissues with enough energy to be able to return to the heart after
they journey through the tissues. Capillaries have no muscle at all in the walls. Their
very thin-walled design allows them to have efficient exchange with the tissue cells. The
venules and veins have a thin muscular wall that helps them accommodate extra volumes
of blood as the blood is being returned to the heart.
In this exercise, you will be looking at the main arteries and veins of the body. The
names of vessels in the body are often associated with terms that refer to a body region
and the directional terms that you have learned earlier in the semester.
In addition, we will examine the structure of the major lymphatic organs. The lymphatic
system plays important roles in protecting the body from disease as well as helping to
ensure that tissue fluids are recirculated back into the blood supply.
Arteries of Upper Body
In the last exercise, you became familiar with some of the major vessels associated with
the heart. The pulmonary artery emerges from the right ventricle and transports blood
to the lungs. This vessel carries
deoxygenated blood (only artery
in the body to do so) because the
blood has just returned from the
body organs and is on its way to
the lungs to pick up oxygen.
Most arteries of the body are
branches off of the aorta, the
artery associated with the left
ventricle.
The aorta emerges
superiorly from the heart and after
a short distance, makes a large Uturn and begins heading inferiorly
towards the abdomen. The first
part of the aorta is called the
ascending aorta; the U-turn
portion is known as the aortic
arch; and the remainder is called
the descending aorta.
After
passing through the diaphragm,
the aorta enters the abdominal
cavity and is often referred to as
the abdominal aorta.
The first branches off of the aorta provide blood to the myocardial cells of the heart.
These vessels, coronary arteries, can be seen running over the outer surface of the heart.
Three main vessels emerge from the aortic arch. The first major branch off of the aortic
arch is the brachiocephalic artery. This very short artery quickly splits into two other
vessels: the right common carotid artery and the right subclavian artery. The left
subclavian and left common carotid arteries come off separately from the aortic arch
as the next two main branches.
The common carotid arteries travel superiorly through the neck region on either side of
the airway (i.e. the trachea). The pulse can be taken in the neck by placing your fingers
into the groove between the muscles just inferior to the mandible. At about the level of
the ear, the common carotid arteries split into the internal and external carotid arteries.
The internal carotid artery (which cannot be seen on the pictures) enters the skull and
provides most of the nutrients to the tissues of the brain. The vertebral and basilar
arteries provide the remaining blood flow to the brain tissue.
The external carotid artery supplies nutrients to the surface areas of the skull and face.
The facial artery, supplying the skin and some muscles of the face, and the maxillary
artery (this vessel is internal and cannot be seen on the picture), supplying deeper
muscles and the oral cavity, are important branches of the external carotid artery. The
facial artery is an important pressure point used to stop bleeding from the face. Pressure
is applied to the vessel where it curves around the mandible.
The subclavian arteries travel
towards the arms. In the region of the
armpit, the vessel receives a new
name – not because of any branching,
but merely due to the change of
location. The vessel will now be
known as the axillary artery. As
the vessel moves into the upper arm,
the name is once again changed – due
to a new location – to the brachial
artery. These names are similar to
terms you learned for the body
regions earlier in the semester
associated with the armpit and upper
arm areas. The brachial artery is an
important
pressure
point
for
controlling bleeding from the hand or
arm. Pressure is applied to the midbrachial region, in the crevice
between the biceps and triceps
muscles.
In the area of the elbow, the vessel
finally has its first major branches.
The branch that runs down the medial aspect of the lower arm is the ulnar artery. The
branch that runs laterally in the lower arm is the radial artery. These names refer to the
bones that are located in the same area. The radial artery is the vessel used for taking the
pulse in the wrist region.
Arteries of Lower Body
As the aorta enters the abdominal cavity, a number of additional major vessels emerge.
The celiac artery (trunk) is
the first abdominal branch
off of the aorta. This very
short vessel splits almost
immediately into the gastric
artery
(supplying
the
stomach), the splenic artery
(supplying the spleen), the
hepatic artery (supplying the
liver), and the pancreatic
artery
(supplying
the
pancreas).
The superior mesenteric
artery is the next branch to
emerge from the abdominal
aorta. This can only be seen
as a small “stump” on the
picture because the vessel
travels out of the aorta and
into the tissues that are
associated with the small
intestine. That tissue has
been cut away on this model
to allow you to visualize the
vessels underneath.
This
normally fans out with many
branches to the intestine.
A short distance inferior to the superior mesenteric artery, the renal arteries emerge
from the sides of the aorta. One renal artery supplies blood to each kidney. The gonadal
arteries branch off of the aorta just below the renal arteries. These vessels supply the
reproductive organs of the male and female. These vessels are usually called ovarian
arteries in the female and the testicular arteries in the male.
The inferior mesenteric artery is the last branch off of the abdominal aorta. This vessel
supplies blood to the large intestine.
The aorta ends by splitting into the two common iliac arteries which lead to the lower
portion of the body. Like the common carotid arteries in the head/neck region, the
common iliac arteries have internal and external branches. The internal iliac artery
supplies the pelvic cavity organs. The external iliac artery transports blood to the leg.
As soon as the external iliac artery exits the pelvic cavity, the name is changed to the
femoral artery. This vessel supplies blood to the thigh region. Below the knee, the
femoral artery splits into the anterior tibial artery and the posterior tibial artery which
run down the front and back of the lower leg, respectively.
Veins of Lower Body
The return of blood to the heart from various
body structures follows a path similar to the
flow of blood out to the various body areas.
You will find that many of the veins bear the
same names as the arteries that travel to the
same body region. Blood often has difficulty
returning to the heart through the veins,
however, due to the low blood pressures within
the vessels so there will be a number of
“alternative” routes through which the blood can
make the journey.
Blood is collected from the lower leg by the
anterior tibial vein and posterior tibial vein.
These run next to the arteries of the same name
and cannot be seen on the picture. The tibial
veins flow into the femoral vein which runs
through the thigh region and feeds into the
external iliac vein once inside the pelvic cavity.
Blood from the leg can also be routed through the great saphenous vein, a long vessel
that spans the area from the ankle to the groin. This vessel is often removed due to the
development of varicose veins, a condition in which the vein valves become damaged.
This vessel is also used for cardiac bypass surgeries, providing the “new” blood vessel
segments that will be used to bridge over the blocked areas of the coronary arteries in the
heart.
In the pelvis, the external iliac vein
joins with the internal iliac vein
returning blood from the pelvis, to
form the common iliac vein. The
short common iliac veins fuse
forming the inferior vena cava.
As the inferior vena cava makes its
way through the abdomen, blood
returning from the abdominal
organs will be routed to this vessel.
The renal veins return blood from
the kidneys directly into the inferior
vena cava. Blood from most of the
other abdominal organs, however,
will be making a detour prior to
entering the vena cava.
Blood collected from the stomach,
small intestine, most of the large
intestine, pancreas, and spleen
travels through veins that join to
form the hepatic-portal vein which
makes a stop at the liver before traveling back to the heart. This unusual path allows the
liver to modify the composition of the blood and remove harmful materials before the
blood returns to the heart and circulates back around to the body organs. Blood leaving
the liver enters the inferior vena cava via the hepatic veins.
The inferior vena cava then enters the thoracic cavity and drains into the right atrium of
the heart.
Veins of Upper Body
Blood returning from the arm travels through the radial vein and ulnar vein of the lower
arm. These vessels run along side the arteries of the same name. These vessels cannot be
seen on the pictures because the vessels were removed so that you could view the
arteries.
The radial and ulnar veins join to
form the brachial vein which
becomes the axillary vein when
the vessel reaches the area of the
armpit.
In the area of the
shoulder the name of the vessel
changes to the subclavian vein.
There are several “alternative”
routes for the blood returning
from the arms. The basilic vein
runs medially up the arm from
the wrist to the axilla where it
joins with the brachial vein.
The accessory cephalic vein and
the cephalic vein run laterally up
the forearm and upper arm,
respectively. The cephalic vein
joins the axillary vein in the
shoulder.
The median cubital vein cuts
diagonally
across
the
antebrachial region, connecting
the cephalic and basilic veins.
Blood returning from the head
travels through the jugular veins.
These vessels form from the
joining of veins from areas that
were served by the branches of the
common carotid arteries. There
are no carotid veins and there are
no jugular arteries! The arteries in
the head/neck are the carotids and
the veins in the head/neck are the
jugulars.
The jugular veins from the head
join with the subclavian veins
from the arm to form the
brachiocephalic veins. The left
and right brachiocephalic veins
fuse to from the superior vena
cava which enters the right atrium
of the heart.
Lymphatic System
The lymphatic system is structured somewhat like
the vasculature of the circulation. Tiny lymphatic
capillaries collect up excess tissue fluid and send
it to the larger, vein-like lymphatic vessels. These
lymphatic vessels travel to various parts of the
body, often along side the circulatory vessels. The
fluid, known as lymph, eventually is returned to
the blood circulation when the largest lymphatic
vessels (the right lymphatic duct and the thoracic
duct) join into the subclavian veins.
Before returning the lymph to the blood
circulation, the fluid is filtered by lymph nodes.
Lymph nodes are responsible for filtering the fluid
that was retrieved from the local area near the
lymph node.
Lymph nodes are not evenly
distributed over the entire body. They tend to
congregate near portals of entry, the places where
it is likely that environmental materials would enter
the body. As a result, there are numerous lymph
nodes in the head, neck, thorax, and abdomen, but
few in the region of the arms and legs except where
the limb attaches to the trunk of the body.
Because there are so many surfaces that are exposed
to the environment up in the head region, the tonsils
have been placed into the throat region. This
additional set of special lymph nodes provides a
second filtering of the lymph before it returns to the
blood supply. The pharyngeal tonsils lie posterior
to the nasal area and are more commonly known as
the adenoids. The palatine tonsils are found in the
posterior oral cavity and are referred to as the tonsils.
The lingual tonsils lie at the base of the tongue.
The spleen is located in the upper left abdomen and filters
blood much the same way that the lymph nodes filtered the
lymph. Anything that was missed by the lymph nodes or
that was placed directly into the blood could be captured by
the spleen.
The final organ, the thymus, is found in the thorax, just
anterior to the large vessels associated with the heart. This
organ is very large in children, but atrophies (i.e. shrinks)
after puberty. The thymus is involved in the maturation of
the T-lymphocytes that are important for immunity.