Lymphatic system
Lymph
·
Lymph is the clear, nearly colorless, alkaline fluid
that occupies the space between all cells of the body.
·
The term for this is ‘interstitial fluid’, and it is
similar to blood plasma.
·
It is 95% water. It seeps in and out through the
walls of very small vessels called capillaries.
·
Carries
the nutrients, oxygen and hormones to cells
·
Carries
waste back to capillaries
Lymph is mostly fluid from blood plasma.
Lymphatic system
•
The lymphatic system is connected to the circulatory
system.
•
It consists of capillaries, vessels, ducts, and
nodes. This system transports lymph one-way…back to the blood stream.
There is no pump, but the lymph moves via skeletal muscle action, respiratory
movement, and contraction of smooth muscle in vessel walls.
Structures of the lymphatic system
•
Lymph
fluid
•
Lymph
vessels
•
Lymph
nodes
•
Lymph
glands
Lymph vessels
·
Transport
excess lymph fluid back to circulatory system.
·
Located
in almost all tissues and organs
·
Closely
parallel veins
·
Since
the lymphatic system has no pump, skeletal muscle contractions moves lymph
through the vessels
•
Valves
prevent backward flow
•
Only
move in one directions (from body towards heart)
•
Lymph
vessels parallel to blood vessels
•
Lacteals
•
Specialized
lymph vessels in the small intestines that absorbs digested fat
•
Lymph
vessels join together to form larger lymph vessels à
•
Large
lymph vessels join together to form lymphatics à
•
Two
main lymphatics:
1.
Thoracic duct
§
Also
called the left lymphatic duct
§
Receives
lymph from the left side of chest, head, arm and neck, the entire abdominal
area and entire lower body
§
Dumps
back into left subclavian à SVC
2.
Right lymphatic duct
§
Receives
lymph from the right side of the chest, head, arm and neck
§
Dumps
back into right subclavian à SVC
Lymph nodes
·
Tiny,
oval-shaped structures!
·
Range
in size from a pinhead to an almond
·
Site
of lymphocyte formation and filter for screening out harmful substances (ex:
bacteria, cancer)
·
If
substances can’t be destroyed, node becomes inflamed
Tonsils
Masses of
lymphatic tissue that produce lymphocytes and filter bacteria
·
3
pairs
1.
Palatine
tonsils: sides of throat
2.
Adenoids
/ Pharyngeal tonsils: upper throat
3.
Lingual
tonsils: back of tongue
Spleen
·
Sac-like
mass of lymphatic tissue
·
LARGEST
lymphatic structure
·
Located
in the LUQ – just below diaphragm
·
Forms
lymphocytes and monocytes
·
Filters
blood
·
Stores
large amounts of RBCs – contracts during vigorous exercise or loss of blood to
release RBCs
·
Destroys
or removes old or fragile RBCs – preserves hemoglobin
Thymus gland
·
Located
in the upper, anterior thorax (chest), above the heart
·
Produces
T lymphocytes
·
Also
an endocrine gland because also secretes hormones
Functions of the lymphatic system
The lymphatic system has 3 primary functions:
1. Transports proteins and fluids,
lost by capillary seepage, back to the bloodstream.
2. Participates in the body’s immune response.
3. The pathway for the absorption
of fats from the small intestine into the bloodstream.
Lymph nodes are filters, slowing down and cleaning the lymph before
returning it to the blood.
Lymph nodes trap and sometimes become swollen with bacteria that has
invaded the body AND the white blood cells that fight that bacteria.
The lymphatic system and cancer
•
The lymphatic system plays an important role in the development
or spread of cancer.
•
Cancer that starts in the lymph nodes is called a
lymphoma.
•
When cancer cells break off a tumor and spread into
the lymph nodes, it is known as metastatic cancer.
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