Download LYMPHOID SYSTEM,LYMPHATIC VESSELS,LYMPH NODES

LYMPHOID SYSTEM,LYMPHATIC VESSELS,LYMPH
NODES,LYMPHOID ORGANS,RIGHT LYMPHATIC DUCT
AND THORACIC DUCT,FUNCTIONS,SPREAD OF
CANCER
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LEARNING OBJECTIVE
At the end of lecture student must be able to know,
Define lymphoid/lymphatic system.
Define lymphatics and lymph nodes.
Describe briefly the structure of lymph node.
Enlist various lymphoid tissues and lymphoid organs.
Identify large lymphatic channels:right lymphatic duct and
thoracic duct.
Identify the role of lymphatic system ininfections.
Identify the role of lymphatics in the spread of cancer.
Lymphoid System
 consists of all of the tissue aggregates
and organs composed of lymphoid
tissue which function together to
produce our specific resistance to
disease (immunity).
lymphatic system
 The lymphatic system can be broadly
divided into the conducting system and
the lymphoid tissue.
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 The conducting system carries the lymph and consists
of tubular vessels that include the lymph capillaries, the
lymph vessels, and the right and left thoracic ducts.
 The lymphoid tissue is primarily involved in immune
responses and consists of lymphocytes and other white
blood cells enmeshed in connective tissue through
which the lymph passes.
 Regions of the lymphoid tissue that are densely packed
with lymphocytes are known as lymphoid follicles.
 Lymphoid tissue can either be structurally well
organized as lymph nodes or may consist of loosely
organized lymphoid follicles known as the mucosaassociated lymphoid tissue (MALT)
 Lymphoid System
 The lymphatic vessels are arranged into a superficial
and a deep set.
 On the surface of the body the superficial lymphatic
vessels are placed immediately beneath the integument,
accompanying the superficial veins; they join the deep
lymphatic vessels in certain situations by perforating
the deep fascia.
 In the interior of the body they lie in the submucous
areolar tissue, throughout the whole length of the
digestive, respiratory, and genito-urinary tracts; and in
the subserous tissue of the thoracic and abdominal
walls
lymphatic system
Lymph
• Lymph is the fluid that is formed when interstitial
fluid enters the initial lymphatic vessels of the
lymphatic system.
• The lymph is then moved along the lymphatic vessel
network by either intrinsic contractions of the
lymphatic vessels or by extrinsic compression of the
lymphatic vessels via external tissue forces (e.g. the
contractions of skeletal muscles).
LYMPHATIC CHANNELS
 Tubular vessels transport back lymph to
the blood ultimately replacing the volume
lost from the blood during the formation
of the interstitial fluid.
 These channels are the lymphatic
channels or simply called lymphatics
Lymphoid tissue
 Lymphoid tissue associated with the lymphatic system
is concerned with immune functions in defending the
body against the infections and spread of tumors.
 It consists of connective tissue with various types of
white blood cells enmeshed in it, most numerous being
the lymphocytes.
 The lymphoid tissue may be primary, secondary, or
tertiary depending upon the stage of
lymphocyte development and maturation
it is involved in.
 The tertiary lymphoid tissue typically
contains far fewer lymphocytes, and
assumes an immune role only when
challenged with antigens that result in
inflammation.
 It achieves this by importing the
lymphocytes from blood and lymph.
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functions
It is responsible for the removal of interstitial fluid from
tissues
It absorbs and transports fatty acids and fats as chyle to
the circulatory system
It transports immune cells to and from the lymph nodes
in to the bone
The lymph transports antigen-presenting cells (APCs),
such as dendritic cells, to the lymph nodes where an
immune response is stimulated.
The lymph also carries lymphocytes from the efferent
lymphatics exiting the lymph nodes.
Lymphoid tissue
 Found in many organs, particularly the lymph nodes,
and in the lymphoid follicles associated with the
digestive system such as the tonsils.
 Also includes all the structures dedicated to the
circulation and production of lymphocytes, which
includes the spleen, thymus, bone marrow and the
lymphoid tissue associated with the digestive system.
 consists of all of the tissue aggregates and organs
composed of lymphoid tissue which function together to
produce our specific resistance to disease (immunity).
Lymphoid Tissue
 Consists primarily of two tissue
components:
 Reticular tissue which forms the
structural matrix supporting the
functional tissue. It is chiefly reticular
connective tissue.
 2. Lymphatic tissue which is
composed of lymphocytes and
macrophages.
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Lymphoid Tissue
These two components will form a diffuse, simple
aggregate in many tissues of the body, for example:
An infiltration of the lamina propria of mucous
membranes in the alimentary canal (Peyer's patches)
and respiratory tract (tonsils)
2. In regions subjected to chronic inflammatory
reactions.
3. In loose connective tissue.
4. In the walls of viscera.
lymphoid organ
 When these two tissues
(lymphatic and reticular) are the
predominant components in an
organ, it is referred to as a
lymphoid organ.
 Examples of lymphoid organs
would be the lymph nodes,
spleen and thymus.
The Lymph Node
 An oval structure, 1 to 25mm in
diameter.
 Enclosed by a capsule with an
internal framework of trabeculae
consisting of collagenous and
reticular fibers.
 Found primarily in the proximal
area of the limbs, i.e., axilla,
inguinal and cervical nodes, as well
as, the retroperitoneal area of the
pelvis and abdomen and the
surface of thoracic and abdominal organs.
 Contains two regions. outer:CORTEX AND inner
MEDULLA.
 A cortex consisting of densely packed nodules of
lymphocytes found just below the subscapular sinus.
 The nodules are called primary nodules(lymph
follicles).
 Each one contains lymphocytes, plasma cells and
macrophages.
MEDULLA OF LYMPH NODE
 A medulla containing cords or rows of lymphocytes
separated from one another by sinuses.
 Medullary sinuses communicate with efferent
lymphatics and contain reticular cells and macrophages.
Path of lymph through the node
 Path of lymph through the node:
 a. multiple afferent lymphatic empties lymph into the
subcapsular sinus.
 b. lymph flows through sinuses around germinal
centers, along side trabeculae and through the medulla.
Cells of the RES line these sinuses and will phagocytize
foreign material.
 c. lymph leaves the node through the single efferent
lymphatic.
 d. lymphocytes move readily with the lymph. The B and
T lymphocytes can leave the circulating blood through
venule walls and enter lymphatic sinuses and germinal
centers. Lymphocytes can also pass into the blood from
lymph sinuses or travel with the lymph for reentry via
the right lymphatic and thoracic ducts.
 e. sinusoids of the node are lymphatic not blood
vascular.
 Path of lymph through the node
Mucosa-Associated Lymphoid Tissues
 Lymphoid tissue located beneath the mucosal
epithelial lining of the respiratory and digestive systems
protects the body against pathogens that may enter the
body via the mucosa.
 The Tonsils- The tonsils are accumulations of lymphoid
tissue surrounding the openings of the digestive and
respiratory tracts.
Mucosa-Associated Lymphoid Tissues
 Palatine tonsils - are located in the
lateral wall of the oropharynx and
covered by a stratified squamous
epithelium.
 Lingual tonsils - are situated in the
lamina propria at the root of the tongue
and also covered by a stratified
squamous epithelium.
 Pharyngeal tonsils - are located in the
upper posterior part of the throat
nasopharyngnx and covered by a
pseudostratified ciliated epithelium with
goblet cells.
PEYER’S PATCHES
- Small accumulations of lymphocytes or solitary
lymph follicles are found scattered beneath the
mucosa throughout the gastrointestinal tract.
- The most prominent accumulations occur in the
ileum and appendix in the form of Peyer's patches.
- In the ileum, they form dome-shaped protrusions
into the lumen.
- Beneath the epithelial lining of the
domes, Peyer's patches extend from
the lamina propria to the submucosa.
Within Peyer's patches.
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spleen
located in the upper left abdominal quadrant.
Unlike the lymph node, the spleen is inserted in the
blood stream.
The spleen clears the blood of aged blood cells and
foreign material.
It is the site of an immune response to blood-borne
antigens, especially in children.
thymus
 The thymus is
composed of two
identical lobes and is
located anatomically in
the anterior superior
mediastinum, in front of
the heart and behind the
sternum. The thymus is
a specialized organ in
the immune system.
 The functions of the thymus are the "schooling" of Tlymphocytes (T cells), which are critical cells of the
adaptive immune system, and the production and
secretion of thymosins, hormones which control Tlymphocyte activities and various other aspects of the
immune system.
thoracic duct
 It is the largest lymphatic vessel
in the body.
 It collects most of the lymph in
the body (except that from the
right arm and the right side of the
chest, neck and head, which is
collected by the right lymphatic
duct) and drains into the systemic
(blood) circulation at the left
brachiocephalic vein between the
left subclavian and left internal
jugular veins.
 SPREAD OF CANCER
 The study of lymphatic drainage of various organs is
important in diagnosis, prognosis, and treatment of
cancer.
 The lymphatic system, because of its physical
proximity to many tissues of the body, is responsible for
carrying cancerous cells between the various parts of
the body in a process called metastasis.
 The intervening lymph nodes can trap the cancer cells.
If they are not successful in destroying the cancer cells
the nodes may become sites of secondary tumors.
 Diseases and other problems of the lymphatic system
can cause swelling and other symptoms.
 Problems with the system can impair the body's ability
to fight infections.
 REFERENCES
 Internet.different sources.
 Grays anatomy(Henry Gray Anatomy of the Human
Body)
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