The lymphatic system helps remove excess fluid and proteins from tissues and returns them to the bloodstream. Lymph vessels drain interstitial fluid from most tissues into the thoracic duct or right lymphatic duct, which empty into subclavian veins. Along with monocytes and macrophages, lymph nodes filter the lymph and phagocytose pathogens and cellular debris. The monocyte-macrophage system, also called the reticuloendothelial system, is comprised of tissue-resident macrophages that protect against infection by phagocytosing invading microbes in tissues like the lungs, liver, spleen, and bone marrow.

1. LYMPHATIC SYSTEM

2. INTRODUCTION
•Lymphatic system is an accessory route
through which fluid can flow from interstitial
spaces into the blood.
•Lymphatics can carry proteins and large
particles away from the tissue which are not
removed by absorption directly into the blood
capillaries.

3. Lymph channels of the body
• Almost all tissues of the body have special lymph channels
• that drains excess fluid from interstitial spaces.
• Exceptions
• superficial portions of the skin, CNS, endomysium of the muscle.
• These have pre-lymphatics
• empties into lymphatic vessels
• In brain empties into CSF Blood

4. • Lower part of the body & left side of head, arm and
chest drains into Thoracic duct venous system at
the junction of Lt. Subclavian vein & Lt. Internal
jugular vein
• Right side of head, neck, arm chest Right lymphatic
duct venous system at the junction of Rt subclavian vein
& Right internal jugular vein

6. Formation of lymph
• Lymph - derived from interstitial fluid
• Protein concentration of lymph -
• Formed in Tissues- 2gm/dl
• Formed in liver - 6gm/dl
• Formed in intestines - 3-4gm/dl
• Thoracic duct lymph - 3-5 gm/dl

7. Flow of lymph
• Rate of lymph flow
• 120ml/hr or 2-3 L/day
• Special structures
• Anchoring filaments
• Valve system
• Capillary endothelial cells
• have contractile actomyosin filaments

8. Factors determine lymph flow
• 1) Interstitial fluid pressure
• 2) Activity of the lymphatic pump
• Increased Interstitial fluid pressure Increases lymph flow
• Factors increasing Interstitial fluid pressure
• Elevated capillary hydrostatic pressure
• Decreased plasma colloid osmotic pressure
• Increased interstitial fluid colloid osmotic pressure
• Increased permeability of the capillaries

10. Activity of lymphatic pump
• Lymphatic pump increases lymph flow
• Lymphatic pumping caused by
• intrinsic factor
• external factor

11. Intrinsic factor
Lymph vessel stretched with fluid
Smooth muscle in the vessel wall contracts
Each segment of lymph vessel between successive valves functions as
separate automatic pump
Filling of segment
Contraction of smooth muscle
Pushing fluid to next segment through the valve

12. External factors
• Contraction of surrounding skeletal muscles
• Movement of the body parts
• Pulsations of arteries adjacent to lymphatics
• Compression of tissues by objects outside the body
• Exercise Lymph flow - 10-30 fold
• Rest Lymph flow

13. Importance of lymphatic system
• Carry large molecules like protein into circulation
• One of the major route of absorption of nutrients from GIT
• carry bacteria to lymph nodes and destroy them
• Control interstitial fluid protein concentration, volume and
pressure

14. RETICULO ENDOTHELIAL SYSTEM
MONOCYTE-MACROPHAGE CELL SYSTEM

15. Introduction
• Our bodies have a special system for Combating the different infections
and toxic agents.
• This system composed of blood leukocytes (WBC’s) and tissue cells
derived from leukocytes.
• WBC’s are the mobile unit of body's protective system.
• Granulocytes & monocytes protect the body against invading organism
by phagocytosis

16. WBC formation, storage and life span:
• . Granulocytes and monocytes are formed in Bone marrow.
• Lymphocytes & plasma cells produced in Lymphogenous tissues
• WBCs formed in BM are stored in marrow until they are needed in the
circulatory system
• Life span of granulocytes in Bloods 4-8 hrs
• in tissues 4-5 days
• for monocytes 10-20hrs in blood
• for tissue macrophages - months.

17. Monocyte macrophage cell system (RES)
•Total Combinations of monocytes, mobile
macrophages, fixed tissue macrophages and few
specialized endothelial cells in the BM, Spleen &
Lymph nodes is called the Reticulo Endothelial
system.
•It is a generalized phagocytic system located in all
tissues - especially in tissues where large quantities of
particles & toxins must be destroyed.

18. Tissue macrophages in skin and subcutaneous
tissues- histiocytes.
• The skin is impregnable to infectious agents.
• Infection of subcutaneous tissue.
Local inflammation gets started
Local tissue macrophages can divide to more in number and
attack & destroy the infectious agents

19. Macrophages in Lymph nodes
• The infectious agents enters the tissues cannot be absorbed
directly into the circulation
They destroyed locally
If it fails enter lymph and flows through the lymph nodes.
Macrophages lining the lymph sinuses phagocytize these
organisms and prevent general dissemination throughout the
body

21. Alveolar macrophages in lungs
• Located in the alveolar walls
• -They phagocytize the particles.
• If the particles are digestible digest them
release digestive products into lymph
• If not digestible form a giant capsule around the particle
slowly dissolve it
• Such capsules formed around tuberculosis bacilli, silica dust, carbon
particles.

22. Macrophages in Liver Sinusoids (Kupffer
cells)
Invading organism through Gastro intestinal tract
enters portal blood
Liver (Kupffer cells)
form effective particulate filtration
None of the organism enters into the general systemic
circulation

23. Macrophages of spleen and Bone marrow
If the invading organism succeeds in entering the
general circulation
defense by tissue macrophages of spleen & Bone
marrow- by phagocytize them

24. In spleen small artery penetrates into the splenic pulp and terminates in small
capillaries.
Whole blood pass through the cords of Red pulp
Blood gradually squeezes through the trabecular meshwork.
enters into circulation through Venous sinuses
• The trabeculae of the Red pulp & venous sinuses lined with macrophages
• They phagocytize unwanted debris in the blood

26. Phagocytosis
• Cellular ingestion of offending agent.
• Surface of the particle
• protective protein coats
• Antibodies adhere to the bacterial membranes
susceptible to phagocytosis
• lysosomes of macrophages contain lipases digest
thick lipid membranes possessed by some bacteria

28. •Macrophages also contain bactericidal agents that kill
most bacteria.
•Oxidizing agents having killing effect are
• superoxide (O2
-), hydrogen peroxide (H₂O₂), and hydroxyl
ions (OH-)
•Lysosomal enzyme -myeloperoxidase, catalize the
reaction between H202 and chloride ions form
hypochlorite → extremely bactericidal.

29. THANK YOU