Download Lymphatic System and Immunity



Fluid Balance, Fat Absorption, Defense
Fluid Balance:
 30L of fluid exits capillaries only 27L will return to
vascular system 3L enters the lymphatic
capillaries as lymph
 Water, plasma, hormones, enzymes & waste

Fat Absorption:
 Absorbs fats from digestive tract through lacteals
making lymph appear milky-chyle

Defense:
 Destroy microorganisms and foreign substances.
Lymphocytes act as part of the immune system &
microorganisms are filtered by lymph nodes and
by blood in the spleen







Lymph-fluid
Lymphocytes
Lymphatic vessels
Lymph nodes
Tonsils
Spleen
Thymus gland




Does not circulate fluid to
and from tissues
Carries fluid from tissue
capillaries to circulatory
system
Lymphatic Capillaries are
closed ended vessels made
of simple squamous
epithelium
More permeable than
blood capillaries


Found in most all tissues of
the body except CNS, bone
marrow, epidermis and
cartilage
Lymphatic capillaries join
together to form lymph
vessels with a beaded
appearance due to
overlapping valves


Lymph moves from small
vessels to larger vessels
Empty into blood in two
locations
 Right lymphatic duct empties
into the right subclavian vein
¼ of body
 Thoracic duct empties into
the left subclavian vein ¾ of

Three factors that assist
Transport of lymph
 Contraction of skeletal
muscle during activity
 Contraction of smooth
muscle in lymph vessels
 Respiration pressure changes

Lymphatic Organs: Tonsils, Lymph nodes, spleen
& Thymus
 When blood and lymph filters through organs, fiber
network traps microorganisms and other material
 Fine reticular fiber network that holds lymphocytes in
place and traps microorganisms

Lymphatic Tissues: Lymphocytes and other cells
 Lymphocytes originate in red bone marrow & carried
to lymphatic organs by blood
 Lymphocytes divide and increase in number when in
the presence of a foreign material causing an immune
response




Palatine Tonsils- “Tonsils”
Pharyngeal Tonsils“Adenoids”
Lingual Tonsils- “Posterior
to tongue”
All provide protection
against pathogens and
other potentially harmful
material entering from the
nose and the mouth.
 Soar throat when sick


Can become chronically
infected and may require
being removed.
In adults, can decrease in
size and may eventually
disappear.



The size of a small seed to
an almond
Most lymph passes
through at least one lymph
node before entering the
blood
Surrounded by a dense
connective tissue capsule
 Lymphatic tissue
 Lymphatic sinuses-spaces
between lymphatic tissue
which contains macrophages
network of fibers


Lymph enters nodes
through afferent vessels
Lymph leaves nodes
through efferent vessel

Superficial Locations:
 Inguinal –nodes in the groin
Activation of the immune
system includes:
 Axillary- nodes in armpit
 Germinal centers-rapidly
 Cervical- nodes in the neck
 When swollen, signs of
infection!

Two Functions:
 Removal of microorganism
and foreign substances from
the lymph as macrophages
 Activation of the immune
system

dividing lymphocytes.

Two Specialized types of
lymph tissues

Major functions of the
spleen:
 White pulp: Lymphatic tissue
 Filters blood instead of lymph
surrounding arteries
 Red pulp: Consists of fibrous
network filled with RBC’s &
macrophages associated with
veins
 Destroys old RBCs
 Removes foreign substances
in the blood through
phagocytosis


The spleen serves as a
reservoir for blood that can
be released in case of
emergencies
A second function of the
spleen is to filter red and
white blood cells from the
blood.



A third job of the spleen is
to store platelets
Most important role of the
spleen is to bring blood
into contact with the
spleen’s lymphocytes
Finally, the spleen
manufactures red blood
cells for the fetuses





Bi-lobed triangular gland
Located in the
mediastinum
Increases in size until 1
years old, then remains the
same
After 60 years, decreases
in size
By 40 year, most of thymus
is replaced with adipose
tissue



Functions as a site for the
production and maturation
of lymphocytes
Lymphocytes do not
respond to foreign
substances while in the
thymus
After maturation,
lymphocytes enter blood
and travel to other
lymphatic tissues.