The lymphatic system absorbs excess fluid from tissues and returns it to the circulatory system. It also plays a role in immunity. The lymphatic system is made up of lymph, lymphatic tissue including lymph nodes and spleen, and lymphatic vessels. During inflammation, chemical messengers are released that increase blood flow and permeability, causing redness and swelling. Leukocytes migrate to the inflamed area to phagocytose and destroy pathogens and recruit more immune cells.

1. Lecture OverviewLecture Overview
Lymphatic System and Components
– What is lymph and how does it travel?
General Immune Reaction- Inflammation
– What is one function of the cells carried in
lymph?
Selected Topics in Immunity

2. Lymphatic SystemLymphatic System
Absorbs excess fluid from the tissues
Returns this fluid to the circulatory system
or the heart
Additional function in Immunity

3. Components of the LymphaticComponents of the Lymphatic
SystemSystem
Lymph
Lymphatic Tissue
Lymphatic Vessels
Thymus
Bone Marrow
Spleen

4. LymphLymph
Lymph
– The clear fluid
absorbed by
the lymphatic
system
Lymphatic
Tissue
– Clusters of
Lymphocytes
and
macrophages

5. Lymphatic TissueLymphatic Tissue
Malt: (Mucosa Associated Lymphatic Tissue)
– Diffuse array of lymphocytes found along body
passages in mucous membranes.
– Examples of malt: lining of the stomach and
respiratory tract
Lymph nodules:
– Dense clusters of Lymphocytes
– Transient: pop up during infection

6. Lymphatic VesselsLymphatic Vessels
 Carry and Transport
Lymph and proteins
 Similar Structure to
veins
– Tunica Interna:
Thin inner lining
and valves
– Tunica Media:
Elastic fibers and
Smooth Muscle
– Tunica Externa:
Thin Outer Layer

7. Lymphatic FiltersLymphatic Filters
Lymph Nodes- Screen and Filter
Lymph for infectious particles
Spleen- Screen and Filter Blood for
old, dead cells and infectious particles

8. Subclavian
2 collecting Trunks
6 Lymphatic Trunks
More Collecting Vessels
Lymph Nodes
Collecting Vessels
Lymphatic Vessels

9. Lymphatic MovementLymphatic Movement
No pump
Rhythmic contraction of the lymph vessels
Skeletal Muscles
How is backflow prevented?

11. Immune Cell GeneratorsImmune Cell Generators
Bone Marrow- Makes B- Cells
Thymus- Makes T- Cells

12. ThymusThymus

13. Break for
Dynamic Human

14. InflammationInflammation
Non-specific response to tissue trauma or
infection

15. 44 signs of Inflammationsigns of Inflammation

16. 44 signs of Inflammationsigns of Inflammation
Redness
Swelling
Heat
Pain
What’s the purpose of pain?

17. Purpose of InflammationPurpose of Inflammation
Remove Invading Pathogens
Remove Debris of Damaged Tissues
Initiate Tissue Repair

18. Mediators of InflammationMediators of Inflammation
Chemical Messengers
Leukocyte

19. Chemical MessengersChemical Messengers
 Released by mast cells in response to damage
 Bradykinin, Histamine, and Leukotrienes
– Increases Local Blood Flow to distressed area
 Stimulates Vasodilation
 Increases Permeability of Capillaries
 What’s Accomplished?

20. Chemical MessengersChemical Messengers
Bradykinin, Histamine, and Leukotrienes
– Increases Local Blood Flow
 Stimulates Vasodilation
 Increases Permeability of Capillaries
What’s Accomplished?
– Heats area causes redness and swelling
– Dilutes toxins and helps Remove waste
– Supplies oxygen and nutrients for tissue repair

21. Pain ResponsePain Response
Purpose?
Causes?

22. Pain ResponsePain Response
Purpose? Prevents further injury to area.
Causes?
– Direct Nerve Damage
– Pressure from Swelling
– Chemical Stimulation particularly bradykinin

23. Leukocyte DeploymentLeukocyte Deployment
Leukocyte: any white blood cell including
T cells, B cells, granulocytes, platelets,
basophils, mast cells, monocytes and
macrophages
Leukocytes Migrate toward inflammed area
Why? TO KILL and RECRUIT

24. Leukocyte DeploymentLeukocyte Deployment
Leukocytes Migrate to inflammed tissue
How?
1. Margination or pavementing: To
migrate to the wall of a capillary
2. Diapedesis: Passage of blood cells
through vessel wall into tissue
3. Chemotaxis: Movement of a cell
towards or away a chemical source

25. What do the leukocytes planWhat do the leukocytes plan
to do?to do?
Phagocytosis: release of toxic chemicals
Recruit more leukocytes

26. PhagocytosisPhagocytosis
Leukocytes consume and destroy foreign
invaders and dead cells
Ejected as Pus

28. Break forBreak for
Dynamic HumanDynamic Human

29. Selected Topics in ImmunitySelected Topics in Immunity