ANATOMY & PHYSIOLOGY OF LYMPHATIC SYSTEM-LYMPHATIC ORGANS,LYMPH,LYMPHNODE,LYMPHATIC VESSELS,SPLEEN

1. THE LYMPHATIC SYSTEM
By Ms. Sementha Gabrila Senapati

2. INTRODUCTION
• The body cells are bathed in interstitial ( tissue)
fluid, which leaks constantly out of the blood
stream through the permeable walls of blood
capillaries.
• Some tissue fluid diffuses through the more
permeable walls of lymph capillaries, forming
lymph.
• Lymph passes through vessels of increasing size & a
varying number of lymph nodes before returning to
the blood.

3. The lymphatic system consist of:-
• Lymph
• Lymph vessels
• Lymph nodes
• Lymph organs(e.g.spleen & thymus)
• Diffuse lymphoid tissue, e.g.tonsils
• Bone marrow

5. FUNCTIONS OF LYMPHATIC
SYSTEM:-
• 1.TISSUE DRAINAGE:-
• About 3-4 litres of fluid, is drained away by the lymphatic vessels.
• 2.ABSORPTION IN THE SMALL INTESTINE:-
• fat & fat soluble materials, e. g. the fat soluble vitamins, are
absorbed into the central lacteals( lymphatic vessels) of the villi.
• 3.IMMUNITY:-
• The lymphatic organs helps in the production & maturation of
lymphocytes, the WBC responsible for immunity.
• Bone marrow is considered to be lymphatic tissue, since
lymphocytes are produced there.

6. LYMPH & LYMPH VESSELS:-
• Lymph is a clear watery fluid.
• Lymph transports the plasma proteins that seep out of
the capillary beds back to the blood stream.
• It also carries away larger particles, eg. Bacteria & cell
debris from damaged tissues, which can then be
filtered out & destroyed by the lymph nodes.
• Lymph contains lymphocytes(defence cells)
• In the lacteals of the small intestine, fats absorbed into
the lymphatic give the lymph(chyle), a milky
appearance.

9. LYMPH CAPILLARIES
• These originate as blind-end tubes in the interstitial
spaces.
• Nearly all tissues have a network of lymphatic
vessels, except in the central nervous system, the
cornea of the eye, the bones & the most superficial
layers of the skin.

11. LARGER LYMPH VESSELS
• Lymph vessels are found running alongside the arteries
& veins serving the area.
• Has a fibrous covering, a middle layer of smooth
muscle & elastic tissue & an inner lining of
endothelium.
• Lymph vessels have numerous cup-shaped valves to
ensure that lymph flows in a one way system towards
the thorax.
• The lymphatic pump:-the muscle layer in the walls of
the large lymph vessels has an ability to contract
rhythmically.

12. • Lymph vessels become larger as they join together,
forming two large ducts:-
• 1) thoracic duct
• 2) right lymphatic duct, empty the lymph into the
subclavian veins.

14. 1) THORACIC DUCT
• Begins at the cisterna chyli, a dilated lymph channel
situated in front of the first two lumbar vertebrae.
• 40cm long, opens into the left subclavian vein in
the root of the neck.
• It drains lymph from both legs, the pelvic &
abdominal cavities, the left half of the thorax, head
& neck & the left arm.

16. RIGHT LYMPHATIC DUCT
• Dilated lymph vessel about 1 cm long.
• Lies in the root of the neck & opens into the right
subclavian vein.
• It drains lymph from the right half of the thorax,
head & neck & the right arm.

18. LYMPHATIC ORGANS AND
TISSUES
• LYMPH NODES:-
• oval or bean-shaped organs that lie often in groups.
The lymph drains, usually 8-10 before returning to
the venous circulation.
• These nodes are as small as a pin head & some are
the largest about the size of an almond.

20. STRUCTURE
• Lymph nodes have an outer capsule of fibrous
tissue that dips down into the node substance
forming partition, or trabeculae.
• The main substance of the node consists of
reticular & lymphatic tissue containing many
lymphocytes & macrophages.
• Each node has a concave surface called the hilum
where an artery enters & a vein and the efferent
lymph vessel leave.

21. • Lymph from the head & neck passes through deep &
superficial cervical nodes.
• Lymph from the upper limbs passes through nodes
situated in the elbow region then through the deep &
superficial axillary nodes.
• Lymph from organs & tissues in the thoracic cavity
drains through groups of nodes situated close to the
mediastinum, large airways, oesophagus & chest wall.
• Most of the lymph from the breast passes through the
axillary nodes.

22. • Lymph from the pelvic & abdominal cavity passes
through many lymph nodes before entering the
cisterna chyli.
• The lymph from the lower limbs drains through the
deep & superficial nodes including behind the knee
& the groin.(inguinal nodes)

24. FUNCTIONS
• 1) FILTERING & PHAGOCYTOSIS:-
• Lymph is filtered by the reticular & lymphatic tissue.
• Particulates include bacteria, dead and live phagocytes
containing ingested microbes, cells from malignant tumors,
worn out & damaged tissue cells & inhaled particles.
• Organic material is destroyed in lymph nodes by macrophages
& antibodies.
• Some inorganic inhaled particles cannot be destroyed by
phagocytosis.
• These inorganic materials remain inside the macrophage,
either causing no damage or killing the cell.

25. • Materials not filtered out & dealt with one lymph
node passes onto successive nodes& by the time
lymph enters the blood it is usually been cleared of
foreign matter & cell debris.
• In some cases where phagocytosis of bacteria is
incomplete they may stimulate inflammation &
enlargement of the node. (Lymphadenopathy)
•

26. 2) PROLIFERATION OF
LYMPHOCYTES
• Activated T & B lymphocytes multiply in lymph
nodes.
• Antibodies produced by sensitized B lymphocytes
enter lymph & blood draining the node.

28. SPLEEN
• The spleen contains reticular & lymphatic tissue &
is the largest lymph organ.
• Position:-left hypochondriac region of the
abdominal cavity between the fundus of the
stomach & the diaphragm.
• Purplish in colour, varies in size.
• 12 cm long, 7cm wide & 2.5 cm thick.
• It weighs about 200gm.

30. ORGANS ASSOCIATED WITH THE
SPLEEN

31. STRUCTURE
• Slightly oval in shape with the hilum on the lower medial
border.
• Anterior surface is covered with peritoneum.
• Enclosed in a fibroelastic capsule that dips into the organ,
forming trabeculae.
• The cellular material consisting of lymphocytes &
macrophages is called splenic pulp, & lies between the
trabeculae.
• Red pulp is the part suffused with blood & white pulp
consist of areas of lymphatic tissue where there are sleeves
of lymphocytes & macrophages around blood vessels.

33. • The structures entering & leaving the spleen at the hilum are:-
• Splenic artery( branch of the coeliac artery)
• Splenic vein( branch of the portal vein)
• Lymph vessels ( efferent only)
• Nerves.
• Blood passing through the spleen flows in sinusoids( distinct
pores between the endothelial cells,in close association with
splenic pulp.
• ThisThis is essential for the spleens function in removing
ageing or damaged cells from the blood stream.

35. FUNCTIONS
• 1) PHAHOCYTOSIS:-old & abnormal erythrocytes are
mainly destroyed in the spleen, and the breakdown
products, bilirubin and iron, are transported to the
liver via the splenic & portal veins. Other cellular
material eg. Leukocyte, platelets & bacteria are
phagocysed in the spleen.
• 2)STORAGE OF BLOOD:-the spleen contains up to
350 ml of blood, & in response to sympathetic
stimulation can rapidly return most of this volume to
the circulation. Eg. In hemorrhage.

36. • 3) IMMUNE RESPONSE:-The spleen contains T- &
B- lymphocytes, which are activated by the
presence of antigens. Eg. In infection. Lymphocytes
proliferation during serious infection can cause
enlargement of the spleen ( spleenomegaly)
• 4) ERYTHROPOIESIS:-The spleen & liver are
important sites of fetal cell production, & the
spleen can also fulfil this function in adults in times
of great need.

37. THYMUS GLAND
• Position:- upper part of the mediastinum behind
the sternum & extends upwards into the root of
the neck.
• Weight:-10-15 g at birth & grows until puberty,
when it begins to atrophy.
• It's maximum weight at puberty is between 30-40 g
& at middle age it has returned to approx. It's
weight at birth.

40. ORGANS ASSOCIATED WITH
THYMUS

41. STRUCTURE
• The thymus consist of two lobes joined by areolar
tissue. The lobes are enclosed by a fibrous capsule
which dips into their substance, dividing them into
lobules that consist of an irregular branching
framework of epithelial cells & lymphocytes.

42. FUNCTION
• Lymphocytes originates from stem cells in red bone
marrow.
• Those that enter the thymus develop into activated
T- lymphocytes.
• Thymic processing produces mature T-
lymphocytes that can distinguish self tissue from
foreign tissue, and also provides each T-
lymphocytes with the ability to react to only one
specific antigen from the millions it encounter.

43. • T- lymphocytes then leave the thymus & enter the
blood.
• Some enter lymphoid tissues & other circulate in
the blood stream.
• The maturation of thethe thymus & other lymphoid
tissue is stimulated by thymosin, a hormone
secreted by the epithelial cells of the thymus gland.

44. MUCOSA ASSOCIATED LYMPHOID
TISSUE (MALT)
• MALT is found throughout the gastrointestinal tract, in
the respiratory tract & in the genitourinary tract.
• The main groups of MALT are the tonsils & aggregated
lymphoid follicles( Peyers patch)
• Tonsils:-these are located in the mouth & throat, &
therefore destroy swallowed & inhaled antigens.
• Aggregated lymphoid follicles(Peyers patches) these
large collections of lymphoid tissue are found in the
small intestine.

46. LYMPHATIC DISEASES
• Lymphangitis
• Lymphatic obstruction
• Lymphadenitis
• Lymphomas( Hodgkin's & hona hodgkins)
• DISORDERS OF SPLEEN:-
• spleenomegaly

47. ASSIGNMENT
• 1.The lymphatic system consist of?
• 2.List the function of lymphatic system.
• 3. What is the shape of lymphnode?
• 4.Lymph from head & neck drains in_________nodes.
• 5.Write the function of lymphatic organs & tissues.
• 6.Which is the largest lymph organ?
• 7.What is the weight of the spleen.?
• 8.What is the shape of a spleen?
• 9.List the function of spleen.
• 10.Write the position of thymus gland.
• 11.The maturation of thymus is stimulated by which hormone?
• 12.Write the fullform of MALT.

48. Thankyou