1. • Consists of: – Lymph Lymphatic vessels Lymphatic tissue
Lymphatic System
• Consists of: –
Lymph
Lymphatic vessels
Lymphatic tissue
Lymphatic nodules
Lymph nodes
Tonsils
Spleen
thymus

2. Lymphatic System • Lymphatic Vessels • Lymphoid Organs and Tissues
– Functioning in returning interstitial fluid to the
vascular system.
• Lymphoid Organs and Tissues
– House phagocytes and lymphocytes
– Activate the immune response

4. Lymphatic Vessels • Return ISF to the bloodstream
Return leaked plasma proteins to the blood
Fluid within them is called lymph
1-way system flowing toward the heart

6. 1 way system
back towards
the heart

7. How does lymph differ from plasma?
Extracellular
space
Blood
Lymphatic
vessel
PLASMA
INTERSTITIAL FLUID or
TISSUE FLUID
vessel
LYMPH
How does lymph differ from plasma?

8. • 4 types: – Lymphatic capillaries Lymphatic collecting vessels
Lymphatic Vessels
• 4 types: –
Lymphatic capillaries
Lymphatic collecting vessels
Lymphatic trunks
Lymphatic ducts

9. Lymphatic Capillaries
• What do they do?

10. Lymphatic Capillaries
• Blind
• Lined by
endothelium
– Loose
– Overlapping
• Permeability
• Flow

11. Lymphatic Capillaries
• Found just about
everywhere that blood
capillaries are found.
– Exceptions

12. Lymphatic Capillaries
• Lacteals
– Specialized lymphatic
capillaries found in the
villi of the small intestine.
– Absorb fats from the
digestive tract.

14. Lymphatic Capillaries
Collecting Vessels
-Similar to veins (in terms of the 3 tunics)
-Lots of valves
-Both superficial and deep
-Pass thru lymph nodes
* What happens to the lymph there?

16. What feature of lymphatic vessels is visible here? What do they
prevent? Why are they necessary?

17. • Receive lymph from lymphatic collecting • Types:
Lymphatic Trunks
• Receive lymph from lymphatic collecting
vessels.
• Types: –
Jugular
Subclavian
Bronchomediastinal
Intestinal
Lumbar

18. Lymphatic Ducts • Receive lymph from lymphatic trunks.
• Right lymphatic duct
– Receives lymph from the right jugular, right subclavian,
and right bronchomediastinal trunks
– Empties into the right internal jugular vein
• Thoracic duct
– Receives lymph from the left jugular, left subclavian,
left bronchomediastinal, intestinal, and lumbar trunks
– Empties into the left internal jugular vein

21. Lymphatic Vessels Lymphatic Trunks Lymphatic Ducts
Where’s pressure high and
where’s pressure low?
Lymphatic Trunks
What makes lymph flow?
Lymphatic Ducts
Bloodstream

22. Lymph Flow • Lymph flow will be similar to…
• 3 main factors promote lymph flow:
– Skeletal muscle pump
– Respiratory pump
– Lymphatic smooth muscle

23. 1. How does elevating an injured limb affect lymph flow?
2. How would exercise affect lymph flow?
3. How could massage affect lymph flow?
4. In some surgeries for breast cancer, the
lymph nodes along thearm are removed in
order to assess the spread of the disease.
What would be a result of this?

24. What happens when lymph cannot flow?
What could prevent lymph from flowing?
Filaria

25. Lymphoid Cells • Lymphocytes • Phagocytes • Dendritic cells
– T lymphocytes
• Kill virus-infected and cancerous cells
• Coordinate/control immune response
– B lymphocytes
• Become plasma cells which secrete antibodies
• Phagocytes
– Eat and kill and activate the rest of the immune system
• Dendritic cells
– Activate the immune system
• Reticular cells
– Make reticular fibers that support lymphatic tissues and
organs

26. Reticular
connective
tissue forms the
framework of
most lymphoid
tissues and
organs.

27. Lymphoid Tissue • Aggregations of lymphoid cells
Storage/proliferation site for lymphoid cells
Surveillance site
2 main types
– Diffuse lymphatic tissue
– Lymphoid follicles

28. Diffuse Lymphatic Tissue
• What does “diffuse” mean?
• Found in lymph nodes and spleen.
• Especially prominent in the mucous
membranes lining the digestive, respiratory,
urinary, and reproductive tracts.
– Hence the term MALT.

29. Mucosa Associated Lymphatic Tissue
• Where are the
mucosae?
• Why is lymphoid
tissue needed there?
• 2 main types:
– GALT
– BALT

30. Lymphoid Follicles • A.k.a. lymphoid nodules
• Solid, packed spherical clusters of lymphoid
cells and reticular tissues
• Often found as parts of larger lymphoid
organs (e.g., lymph nodes)
• Found in the mucosae
• Large number in the distal ileum and
appendix

31. Lymphoid follicle in the
stomach

32. • Peyer’s Patches – Aggregates of lymphoid follicles found in the
distal small intestine.
• Why there?

33. • Appendix – Blind outpocketing of the cecum.
– Contains aggregates of follicles.

34. Lymphoid Organs • Surrounded by a capsule of dense connective tissue.
• Lymph nodes
• Tonsils, thymus, spleen

35. Lymph Nodes • Filter lymph • Clustered along lymphatic vessels
• Large superficial clusters
in inguinal, axillary, and
cervical regions.

39. Lymph Nodes • Receive lymph from an afferent lymphatic vessel
• Drain lymph into an efferent lymphatic vessel
• Surrounded by dense CT capsule
– Inward extensions (trabeculae) divide it into
compartments
• Reticular fibers support the resident macrophages
and lymphocytes
• Divided into a cortex and a medulla

41. • Cortex contains: – Subcapsular sinus Cortical sinuses Trabeculae
Lymph Nodes
• Cortex contains: –
Subcapsular sinus
Cortical sinuses
Trabeculae
Diffuse lymphatic tissue
Lymphatic follicles

42. Lymph Nodes • Medulla contains:
– Medullary cords (diffuse lymphatic tissue)
– Medullary sinus

44. Flow Through the Node Afferent lymphatic vessel Subcapsular sinus
What happens to the lymph
during this journey?
What does the lymph flow
Cortical sinus
past?
Medullary sinus
Efferent lymphatic vessel

46. Spleen • Largest lymphoid organ • Sits just below the diaphragm,
kind of behind the stomach and
above the kidney and colon.
• What protects it?

48. Spleen • Major function is blood cleansing
– Removal of aged, broken, or malformed RBCs.
• Who does this?
– Removal and destruction of pathogens and foreign
matter.

49. Spleen • Surrounded by a CT capsule w/ inward extending
trabeculae
• Internal framework is provide by reticular fibers.

50. Spleen • Splenic arterioles are surrounded by sheathes
of lymphocytes.
– This is known as the white pulp of the spleen.
– What will happen here?
• The arterioles terminate in splenic capillaries –
which are twisty, sinusoidal, and incomplete.
– The capillaries and the surrounding splenic tissue
is referred to as the red pulp of the spleen.
– Macrophages line the capillary surface.
– Why?

53. Other Spleen Functions
• Storage of RBC breakdown products
• Platelet storage
• Fetal RBC production

54. Which would
contain more
damaged RBCs
and more
pathogens – the
splenic artery or
the splenic vein?

55. Thymus • Largest and most active • Involved in T
in fetus and infancy
• Involved in T
lymphocyte maturation
and selection
– Also, the removal of
those T cells that attack
self tissue
• Growth ceases during
adolescence
• No direct fighting.

59. Tonsils • Form a ring of lymphatic tissue at the
entrance to the pharynx.
• 3 main types:
– Palatine
– Pharyngeal
– Lingual

61. Palatine – located laterally in the posterior oral cavity.
Largest and most often infected.

62. Pharyngeal – located in the
posterior nasopharynx.
A.k.a adenoids.

63. Lingual – located at the
base of the tongue.

65. Not fully encapsulated. Why not?
Contain crypts. What’s their advantage? What’s
their disadvantage?

66. Palatine Tonsil