Chapter 6
The Lymphatic and Immune Systems
The Lymphatic System
Works closely with the immune system to
protect and maintain the health of the body
Functions (3 primary)
1. Absorbing fats and fat soluble vitamins from the
small intestine
2. Removes waste from the tissues
3. Provides assistance to the immune system
Absorption of Fats and Fat-soluble
Vitamins
• Food is digested in the small
intestine where nutrients, fats
and fat-soluble vitamins are
absorbed
• The villi are small finger-like projections that line the
small intestine, which contain blood vessels and
lacteals
• Blood vessels in the villi absorb most of the nutrients
from the digested food directly into the bloodstream
• Fats and fat-soluble vitamins (Vitamins A,D,K, &
E)that cannot be absorbed into the bloodstream are
absorbed by the lacteals of the lymphatic system
Waste Removal from the Tissues
• The lymphatic system removes waste products and
excess fluids created by the cells. It also destroys
pathogens and takes away foreign substances that
are present in the tissues
Cooperating with the Immune System
The lymph nodes work closely with the immune
system to protect the body against invading
microorganisms and diseases.
Major Structures of the Lymphatic System
• Lymph
• Lymphatic vessels and ducts
• Lymph nodes
Lymphatic Circulation
(the secondary circulatory system)
• Transports lymph from tissues throughout the body
and eventually returns this fluid to the veins
So…what is lymph? Are you otterly confused?
Lymph
• Clear, watery fluid that transports waste
products and proteins out of the spaces
between the cells of the body tissues
(interstitial fluid)
• Also destroys bacteria or other pathogens that
are present in the tissues
Interstitial Fluid and the
Creation of Lymph…
• Plasma from arterial blood that flows
out of the capillaries into the spaces
between the cells.
• Transports nutrients, oxygen, and hormones to the cells
• 90% of this fluid is reabsorbed by the capillaries and
returned to venous circulation
• The remaining 10% not reabsorbed becomes lymph,
which is transported by the lymphatic vessels and is
filtered by lymph nodes located along those vessels
Mary, Mary, quite contrary
How does your lymph fluid flow?
• Lymph flows from the lymphatic capillaries into the
progressively larger lymphatic vessels
– Lymphatic vessels have valves to prevent the
backflow of lymph just like veins
• These vessels eventually joint together to form 2
ducts
• Each duct is responsible for draining a specific region
of the body
Right Lymphatic duct
• Collects lymph from the right side of
the head and neck, and the upper right
quadrant of the body and right arm
• empties into the right subclavian vein
Thoracic duct
• The largest lymphatic vessel
• Collects lymph from the left side of the
head and neck, the upper left quadrant
of the trunk, the left arm, and the
entire lower portion of the trunk and
both legs
• Empties into the left subclavian vein
Keep in mind…unlike
the cardiovascular
system, this is a
closed circuit!
Lymph Nodes
• Small bean shaped structures that contain
specialized cells called lymphocytes that are
capable of destroying pathogens
• Unfiltered lymph flows into the nodes, where
the lymphocytes destroy harmful substances
such as bacteria, viruses, and malignant cells
• 400-700 lymph nodes are
scattered throughout the
entire body along the larger
lymphatic vessels
• Approximately half of the
nodes are in the abdomen
3 major groups of nodes:
• Cervical lymph nodes – located on the sides of the (?)
• Axillary lymph nodes – located in the (?)
• Inguinal lymph nodes – located in the (?) area
Additional lymphatic structures
•
•
•
•
•
•
•
Tonsils
Thymus
Spleen
Lacteals (where are these again? What are they for?)
Peyer’s patches
The Vermiform appendix (AKA…the appendix)
Lymphocytes (Specialized white blood cells)
While these structures are made up of lymphoid tissue,
their primary roles are in conjunction with the immune
system!
Tonsils...
• 3 masses of lymphoid tissue
• form a protective ring
around the back of the nose
and upper throat
• Play an important role in
the immune system by
preventing pathogens from
entering the body
(especially the lungs) from
the nose and mouth
Adenoids – located in the
nasopharynx
Palatine tonsils – locate on the
right and left sides of the throat
(these are the ones you typically
see)
Lingual tonsils- located at the
base of the tongue
Thymus
• Located superior to the heart
• While made largely of lymphoid tissue, it is an
endocrine gland that assists the immune system.
Produces hormones that “mature” T lymphocytes
(we will revisit the thymus in Chapter 13)
Peyer’s Patches & the Vermiform
Appendix
• Consist of lymphoid tissue and work with the immune
system to protect against the entry of pathogens through
the digestive tract
Peyer’s patches – located on the walls of the ileum (last
section of the small intestine) generate lymphocytes to help
protect from infection due to pathogens
Vermiform appendix – hangs from the lower portion of the
cecum (1st section of the large intestine). Thought to be a
vestigial organ and while once believed to be useless, recent
research indicates it may play an important role in the
immune system
Another use for the Appendix…
The appendix can be detached from the cecum and
surgically secured to the bladder. The free end is then
brought to the surface of the skin to create an opening for
catheterization. This Mitrofanoff procedure is often times
used for patients with neurogenic bladder.
The Spleen
“Lemme’ spleen..no,
there is to much.
Lemme’ sum up.”
• Located in the (LUQ) of the abdomen, inferior to the
diaphragm and posterior to the stomach
• Filters microorganisms and other foreign material from the
blood
• Forms lymphocytes and monocytes
• Has hemolytic function of destroying worn-out RBC’s and
releasing hemoglobin for reuse
• Also stores extra erythrocytes (?) and keeps the balance
between these cells and the plasma of the blood
Pathology and Diagnostic Procedures of the
Lymphatic System
• The surgical removal of the spleen, also known as a
(?) is most often performed to treat a ruptured
spleen (?). Often caused by abdominal trauma,
spleen injury can cause excessive bleeding from the
spleen (?)
• This procedure may also be used to treat other
conditions, including an enlarged spleen (?), which
can be caused by injury, infectious diseases such as
mononucleosis, or an abnormally functioning
immune system.
Pathology and Diagnostic Procedures of the
Lymphatic System
• Any disease process affecting a lymph node or
lymph nodes is known as (?).
• Swollen glands are an inflammation of the lymph
nodes, also known as (?) and is frequently an
indication of the presence of an infection.
• A benign tumor formed by an abnormal
collection of lymphatic vessels due to a
congenital malformation of the lymphatic system
is called a (?).
Pathology and Diagnostic Procedures of the
Lymphatic System
This condition is swelling due to an
abnormal accumulation of lymph fluid
within the tissues and is known as (?)
There are 2 classifications of this condition…
• Primary lymphedema - a hereditary disorder due to a malformation
of the lymphatic system which most commonly causes swelling in
the feet and legs.
• Secondary lymphedema – caused by damage to the lymphatic
system that most commonly causes swelling in the limb nearest to
the damaged lymphatic vessels. Cancer treatments (surgery, chemo,
and/or radiation) and trauma (burns, injury, and scarring) are the
most frequent cause of this condition. Ex. Elephantitis, due to the
parasitic filarial worms blocking the lymph vessels.