The lymphatic system consists of lymph and lymphatic vessels that transport lymph throughout the body. Lymph is interstitial fluid that has entered lymphatic capillaries and contains lymphocytes, macrophages, viruses, bacteria, and cellular debris. The main components of the lymphatic system are lymph, lymphatic vessels, lymph nodes, lymphatic trunks and ducts, and lymphatic tissue. Lymph flows from lymphatic capillaries through vessels, nodes, trunks and ducts and eventually returns to the blood circulation via the subclavian veins. The lymphatic system functions to transport fluids and nutrients, support immune responses, and absorb dietary fats.

1. Lymphatic SystemLymphatic System
Dr. Mrs. Deepa K. Ingawale
(Mandlik)
Dept. of Pharmacology
Poona College of Pharmacy, Pune
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2. SyllabusSyllabus
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3. Learning ObjectivesLearning Objectives
 To understand lymph composition & lymph flow
 To study function & components of lymphatic system
 To study different cells of lymphatic system
 To study structure & function of spleen
 To describe the anatomy & physiology of lymph node
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4. Body fluid compositionBody fluid composition
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5. Interstitial fluid (ISF)Interstitial fluid (ISF)
 It fills the narrow spaces between the cells of tissues
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Lymphatic SystemLymphatic System
 It consists of lymph & lymphatic vessels that
transport the lymph.
 After interstitial fluid passes into lymphatic vessels, it
is called lymph
 Difference between interstitial fluid & lymph is
location:
 Interstitial fluid is found between the spaces of the
cells, & lymph is located within lymphatic vessels &
lymphatic tissue.

7. Lymphatic tissueLymphatic tissue
 Lymphatic tissue is a specialized form of reticular
connective tissue that contains large numbers of
lymphocytes.
 Lymphocytes are agranular white blood cells
 Two types of lymphocytes participate in immune
responses:
 B cells
 T cells
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FunctionsFunctions
 Fluid & nutrient transport
 Lymphocyte development
 Immune response
 Reabsorbs excess interstitial fluid
• returns it to the venous circulation
• maintain blood volume levels
 Transport dietary lipids
• Transport lipids & lipid-soluble vitamins (A, D, E, & K)
absorbed by the GI tract.

9. ComponentsComponents
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11. LymphLymph
 Fluid present in lymphatic system.
 When ISF passes through lymph capillaries it is called as
lymph.
 It is then transported through lymph vessels to lymph nodes
 From lymph node it is transported to ducts & trunks which
drain lymph to right or left subclavian vein, where it mixes
back with blood.
 Clear, colorless fluid
 Similar to blood plasma but low protein content
 Contain macrophages, viruses, bacteria & cellular debris
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12. Subclavian veinSubclavian vein
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Flow of LymphFlow of Lymph
 Lymphatic capillaries
 Lymphatic vessels
 Lymph nodes
 Lymphatic trunks
 Collecting ducts
 The flow of lymph is regulated by movements of skeletal
muscles & through breathing movements.
 This movement compress the lymphatic vessels & force
lymph towards the subclavian veins.
 Lymphatic vessels contain one way valve that prevents back
flow of lymph.

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Lymphatic CapillariesLymphatic Capillaries
 Microscopic vessels
 tiny thin-walled vessels
 closed at one end
 main purpose is to drain excess
ISF from around the cell to
venous circulation
 wall made up of endothelium
 larger in diameter
 anchoring filaments hold
endothelial cells to the nearby
tissues

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Lymphatic CapillariesLymphatic Capillaries – Lacteals– Lacteals
 A lacteal is a lymphatic
capillary present in mucosa of
small intestine
 It absorbs dietary fats & lipid-
soluble vitamins from the
small intestine.
 Lymph has a milky color due
to the lipid called as Chyle.

16. Small Intestine histologySmall Intestine histology
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17. Lymphatic VesselsLymphatic Vessels
 Lymphatic capillaries combines together to form
lymphatic vessels.
 Thin walled structures that carry lymph.
 Lymph vessels are lined by endothelial cells
 Lymph vessels pushes lymph from lymph capillaries
to the lymphatic trunk & ducts
 Lymphatic vessels resemble small veins.
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18. Lymphatic VesselsLymphatic Vessels
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19. Lymphatic Trunks & DuctsLymphatic Trunks & Ducts
 From lymph vessels, the lymph is delivered to large
lymphatic trunks & ducts.
 Trunks: Six types of trunks are present
• Jugular
• Subclavian
• Bronchomediastinal
• Intestinal
• Lumbar
• Intercostal
 Ducts: Two ducts are present
 Right lymphatic duct
 Thoracic duct
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20. Lymphatic Trunks and DuctsLymphatic Trunks and Ducts
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Lymphatic CellsLymphatic Cells
 Lymphoid cells
 Present in lymphatic system
 Elicit an immune response
 Types of lymphatic cells are:
Macrophages
Epithelial cells
Dendritic cells
Lymphocytes

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Types & Functions of LymphocytesTypes & Functions of Lymphocytes
 T-lymphocytes (T-cells)
 B-lymphocytes (B-cells) Types of Lymphocytes
 Natural Killer cells (NK-cells)
 Migrate through the lymphatic tissues & engulf the micro-
organism (antigens).
 Identified according to tissue or organ where they mature:
• T-lymphocytes mature in Thymus
• B-lymphocytes mature in Bone marrow

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Lymphoid OrgansLymphoid Organs

24. Lymphoid OrgansLymphoid Organs
 Tonsils
Thymus gland
Spleen
 Payer's patches
 Appendix
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25. SpleenSpleen
 Largest lymphoid organ
 Located on the side of
stomach
 Hilum: Blood vessels enters
& leaves the spleen
 Splenic artery
 Splenic vein
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26. Structure of spleenStructure of spleen
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27. StructureStructure ofof SpleenSpleen
 Capsule - Covering of dense connective tissue
 Hilum - Depression on medial surface
- nerves & arteries enter
- veins & lymphatic vessels exit
 Trabeculae - Extensions of capsule, form partitions
within the spleen
 Pulp - Tissue present inside the spleen
- Red pulp: RBCs, macrophages & lymphocytes
- White pulp: Lymphatic tissue
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28. Histology of spleenHistology of spleen
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Functions of SpleenFunctions of Spleen
 Shows an immune response when antigens are
found in blood (White pulp)
 Reservoir of erythrocytes & platelets (Red pulp)
 Phagocytosis of old, defective RBCs & platelets (Red
pulp)
 Phagocytosis of bacteria & other foreign materials.

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31. Lymph NodesLymph Nodes
 Oval or bean shaped structures
 1 to 15 mm in length
 Grayish pink in color
 Scattered throughout the body
 Present in groups
 Superficial groups
 Deep groups
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32. StructureStructure ofof lymph nodelymph node
 Capsule - Covering of dense connective tissue
 Hilum - Depression on medial surface
- 4 to 5 efferent lymph vessels enters & exit, artery & vein
 Trabeculae - Extensions of capsule, form partitions within the
lymph nodes
 Divided into two parts
 Outer cortex: Lymphocytes are arranged in follicles
 Inner medulla: Lymphocytes are arranged in medullary
strands
 Stroma: Along with capsule & trabeculae, reticular fibers &
fibroblast forms the stroma
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33. FunctionFunction
 Filters foreign substances from lymph & passes back to
blood
 These substance are trapped by the reticular fibers
within the lymph node
 Macrophages destroy the foreign substances by
phagocytosis
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34. Lymph NodesLymph Nodes
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35. DisordersDisorders
 Lymphadenitis:
 It is the inflammation or enlargement of a lymph node.
 Acute infection of lymph nodes called as acute lymphadenitis
caused by microbes in the lymph.
 The nodes become inflamed, enlarged, congested with blood.
 Splenomegaly:
 It is an enlargement of the spleen.
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36. DisordersDisorders
 Lymphomas:
 There are malignant tumours of lymphoid tissue.
 These are classified as either Hodgkins or non-Hodgkins
lymphomas.
 It affects individuals between age group of 15 & 35 and it is
more common in males.
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37. QuestionsQuestions
 SAQs:
 Give the functions of lymphatic tissue. (3 M)
 Give different parts of lymphatic tissue. (3 M)
 Note on lymph (3 M, October 2009)
 Note on lymph node. (3 M, October 2009, May 2010)
 Describe composition and function of lymph. (3 M, October
2009)
 Explain structure and function of lymph node. (5 M, October
2009, 2010, May 2011, 2012)
 Explain structure and function of spleen. (3 M, May 2009,
May 2011, October 2011)
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