The lymphatic system is a crucial component of both the circulatory and immune systems, responsible for transporting lymph fluid towards the heart and filtering it through various structures, including lymph nodes and the spleen. Key organs involved include the thymus, which activates T-lymphocytes, and Peyer's patches in the intestine that capture bacteria. Disorders affecting the lymphatic system, such as Hodgkin's lymphoma and lymphedema, can result in significant health complications.

3. LYMPHATIC SYSTEM

4. LYMPHATIC SYSTEM
• DEFINITION:
• The lymphatic system is part of
the circulatory system and an
important part of the immune
system,
• comprising a network of
lymphatic vessels that carry a
clear fluid called lymph (from
Latin, lympha meaning
"water”)directionally towards
the heart.

5. LYMPH
• The interstitial fluid picked up by lymphatic capillaries is known as
lymph.
• Lymph very closely resembles the plasma found in the veins: it is a
mixture of about 90% water and 10% solutes such as proteins,
cellular waste products, dissolved gases, and hormones.
• Lymph may also contain bacterial cells that are picked up from
diseased tissues and the white blood cells that fight these
pathogens.
• In late-stage cancer patients, lymph often contains cancerous cells
that have metastasized from tumors and may form new tumors
within the lymphatic system.

6. COMPOSITION OF LYMPH
• The composition of lymph is
similar to that of plasma but
the constituents have some
additional substances that are
too large to pass through
blood capillary walls
• Ex. macroparticles from
damaged area Damaged cells
by disease and bacteria.

7. LYMPH VESSELS
• These originate as blind end tubes in the interstitial spaces.
Structurally, they are same as blood capillaries.
• Their walls are more permeable to all interstitial fluid including
proteins and cell debris.
• The capillaries joint to form larger lymph vessels.
• Lymph vessels have numerous cup shaped valves that prevent back
flow of movements of lymph in vessels.
• Lymph vessels join together to form two larger ducts:
• (i) The Thoracic duct
• (ii) The right Lymphatic duct

8. LYMPH VESSELS

9. THE THORACIC DUCT
• What is duct?
• A duct is a circumscribed channel leading from an organ.
• Length-40cm
• Ascends through the diaphragm and passes upwards in the thoracic
cavity.
• It drains Lymph from :
• a. Both legs
• b. The pelvic abdominal cavities
• c. Left half of the Thorax
• d. Head & Neck
• e. The Left upper Limbs (Limbs mean hand (upper limbs) and legs
(lower limbs).

10. The right Lymphatic duct
• It lies in the root of the neck
and open into right subclavian
vein
• IT DRAINS LYMPH FROM:
• a. RIGHT HALF OF THE
THORAX (means chest;
thoracic cavity)
• b. NECK
• c. RIGHT UPPER LIMB

11. LYMPH NODES
• A normal young adult body
contains some 400-450
• lymph nodes.
• a. Head and neck -- 60-70
• b. Arms/superficial thorax – 40
• c. Legs/superficial buttocks –
30
• d. Thorax – 100 e.
Abdomen/pelvis – 230

12. LYMPH NODES
• Small oval or bean shaped body
Range from 10 to 20 mm in
diameter.
• Positioned along the course lymph
vessel.
• Slight depression called HILUS
(blood vessels enter & leave
through it)

13. Structure of the lymph node

14. Microscopic Structure of lymph node
• Each lymph node is enclosed by a
fibrous capsule It consist of
Capsule, Cortex, Medulla.
• Fibrous septa or trabeculae
extend from covering capsule
toward centre of node.
• Cortical nodule packed by
lymphocytes surrounded by less
dense area Germinal Center
Cortical nodules within cortex are
separated from each other by
trabeculae
• MEDULLA is composed of
Sinuses & Medullary Cords

15. CELL ZONES IN LYMPH NODES
• ZONE 1- is a region of loosely packed cells, predominantly small
lymphocytes, macrophages and occasional plasma cells.
• ZONE 2 - is a denser region internal to zone 1,composed mainly of small
lymphocytes and macrophages
• ZONE 3- comprises the germinal centers of follicles, its cells include large
lymphoblast, dendritic cells and macrophages.

16. FUNCTIONS OF LYMPH NODES
• DEFENSE:
• As lymph passes through lymph Node reticulo endothelial cells remove
microorganisms & other injurious particles
• HEMATOPOIESIS: Site for final stage of maturation of lymphocytes &
monocytes (Monocytes are a type of leukocyte, or white blood cell. They are
the largest type of leukocyte and can differentiate into macrophages and
myeloid lineage dendritic cells.) that have migrated from bone marrow
• Phagocytic action.
• Production of antibodies.
• Enlargement of lymph nodes, when the area of drainage is infected.
• Activate T and B lymphocytes.
• Filtration of lymph.

18. LYMPHATIC TISSUE OR LYMPHOID ORGAN

19. TONSILS
• Small masses of lymphoid
tissue around the pharynx
• Trap and remove bacteria and
other foreign materials
• Tonsillitis is caused by
congestion with bacteria

20. SPLEEN
• The Spleen is formed partly by
lymphatic system.
• Location-left hypochondriac
region
• Length-12 cm
• Width-7 cm
• Thick-2.5 cm
• Shape-oval
• Relations-
• Posteriorly & Superiorly-
Diaphragm
• Inferiorly-Left colic flexure of
large intestine
• Anteriorly-Fundus of the
stomach

21. STRUCTURE OF SPLEEN
• Reddish, brown organ .
• Looks like a loose fist .
• Enclosed in peritoneum.
• Covered by a capsule.
• The trabaculae subdivides the
structure into lobules.
• The spleen has no afferent
lymphatic vessels.
• It has only efferent lymphatic
vessel.
• Spleen consists red and white
pulp.
• Blood supply:
 Splenic artery
 Splenic vein
 Lymphatic vessels

22. FUNCTIONS OF SPLEEN
• Phagocytosis of Bacteria
• Break down of RBC.
• Production of Antibodies.

23. BONE MARROW
• The Red Bone Marrow is a key
element of the lymphatic system,
• Being one of the primary lymphoid
organs that
• generate lymphocytes from
immature hematopoietic
progenitor cells.
• The bone marrow and Thymus
constitute the primary lymphoid
tissues involved in the production
and early selection of lymphocytes.
• Furthermore, bone marrow
performs a valve-like function to
prevent the backflow of lymphatic
fluid in the lymphatic system.

24. THYMUS GLAND
• Weight-15 gms
• Relations-
• Anteriorly-Sternum.
• Posteriorly –Aortic arch.
• Superiorly- Root of neck.
• Inferiorly-Heart.
• Laterally-Lungs.
• Lobes- two
• Each lobule has aggregation of lymphocytes.
• The cortex is composed of aggregation of lymphocytes. Medulla contains
less lymphocytes. The Thymus gland develops mature T lymphocytes.

25. Thymus gland

26. Structure of thymus gland

27. BLOOD SUPPLY TO THE THYMUS
GLAND
• Inferior thyroid artery.
• Internal thoracic artery.
• Nerves derived from vagus nerve.
Functions :
• Activation of T-lymphocytes
• Production of antibodies.
• Production of Thymosin hormone.
[Thymosins are small proteins present in many animal tissues. they
are named thymosins because they were originally isolated from the
thymus]

28. Peyer’s patches “Tonsils of the
intestine”
• Found in the wall of the
small intestine
• Capture and destroy
bacteria in the intestine

29. Lymphatic nodles

30. Lymphatic nodles
• A group of lymphocytes arranged in a round cluster is called a
lymphatic nodule.
• Many organs contain lymphatic nodules.
• They contribute to defense against microorganisms entering the
body.
• The lymphatic nodules cannot filter lymph.
• Location:
in the walls of alimentary canal (tonsils, appendix and cecum,
Peyer's patches), respiratory passages, and genitourinary tract, as well
as in the other parts of the body.

31. Function: guard the body from and respond to entry of infectious
organisms and toxins.
Primary nodule
Composition: oval concentrations of lymphocytes contained in
meshwork of reticular cells.
Secondary nodule
Composition: Germinal center - a central region that contains large
lymphocytes, mitotic figures, macrophages, and plasma cells.
Function:
• Morphologic indication of lymphatic tissue response to antigen that
represents a cascade of events that includes proliferation (rapid
increase in the number or amount) of lymphocytes, differentiation of
plasma cell, and antibody production.
• outer ring of small lymphocytes.

32. • It is the diffuse system of small concentration of lymphoid tissue found in mucosa of
various organs of our body e.g. lung, gastrointestinal tract.
 It regulates mucosal immunity.
 T-cells, B-cells, Plasma cells and macrophages populate it.
 It contains a light staining region in the center (germinal center) and dark staining
region at the periphery.
 Stimulation of its B-lymphocytes lead to production of Ig A and Ig M (antibodies)
which prevent the adherence of bacteria and viruses to the epithelium, thus blocking
the entry of these micro-organisms to the subepithelial layers of the intestine.
 MALTs are called as :
1. GALT: Gut associated lymphoid tissue.
2. BALT: Bronchus associated lymphoid tissue
3. NALT: Nose associated lymphoid tissue.
4. LALT: Larynx associated lymphoid tissue.
5. CALT: Conjunctiva associated lymphoid tissue

33. Lymphatic disease
• Lymphatic disease is a class of disorders which directly affect the components of the
lymphatic system.
• Diseases and disorders:
• Hodgkin's Disease/Hodgkin's Lymphoma
• This is a type of cancer of the lymphatic system. It can start almost anywhere in the
body.
• It is believed to be caused by HIV, Epstein-Barr Syndrome, age and family history.
Symptoms include weight loss, fever, swollen lymph nodes, night sweats, itchy skin,
fatigue, chest pain, coughing or trouble swallowing.
• Non-Hodgkin's Lymphoma
• Lymphoma is a usually malignant cancer. It is caused by the body producing too
many abnormal white blood cells. It is not the same as Hodgkin's Disease. Symptoms
usually include painless, enlarged lymph node or nodes in the neck, weakness, fever,
weight loss, and anemia.

34. Hodgkin's Disease/Hodgkin's Lymphoma
Non-Hodgkin's Lymphoma

35. Non Hodgkin's
Disease/Hodgkin's
Lymphoma
Hodgkin's
Disease/Hodgkin's
Lymphoma

36. Lymphatic disease
• Lymphadenitis : is an infection of the lymph nodes usually caused
by a virus, bacteria or fungi. Symptoms include redness or swelling
around the lymph node.
• Lymphangitis : Lymphangitis is an inflammation of the lymph
vessels. Symptoms usually include swelling, redness, warmth, pain
or red streaking around the affected area.
• Lymphedema : Lymphedema is the chronic pooling of lymph fluid
in the tissue. It usually starts in the feet or lower legs. It's also a side-
effect of some surgical procedures.
• Lymphocytosis : Lymphocytosis is a high lymphocyte count. It can
be caused by an infection, blood cancer, lymphoma, or autoimmune
disorders that are accompanied by chronic swelling.