1. Human Anatomy and Physiology II Unit IV Circulation and Body Defense Part 4 The Lymphatic System

2. Body Defense Us Them Self Your normal cells and tissues Nonself
Pathogens, abnormal cells (cancer cells)

3. Body Defense
Defense against non-self requires the combined actions of two body systems:
Immune system
Lymphatic system

4. Body Defense Lymphatic system Immune System
Network of lymphoid vessels and organs
Houses the immune system
Immune System
The body’s cellular defense system
Key players are the white blood cells

5. Immunity
Resistance
Susceptibility
2 types of immunity
Innate
Adaptive

6. Immunity Innate Nonspecific Birth Early warning system
1st & 2nd lines of defense
Adaptive
Specific
Adapts
Detects & destroys
Lymphocytes

7. Lymphatic System Topics
Components of the lymphatic system
Functions of the lymphatic system
Organization of lymphatic vessels
Formation and flow of lymph
Lymphatic organs

8. Lymphatic System Components
Clear fluid
Interstitium  lymphatic vessels
Returned to blood by way of lymph ducts
Resembles blood plasma
Contains WBCs (especially lymphocytes) but few red blood cells and no platelets

9. Lymphatic System Components
Lymphatic vessels
Transport lymph
Thin walled, many-valved structures
Lined by endothelial cells, with a thin layer of smooth muscle and adventitia
Skin vs. visceral vessels
Drain into subclavian veins

10. Lymphatic System Components
Lymphatic tissue
Specialized form of reticular connective tissue containing large numbers of lymphocytes
Filtering
Makes up the spleen, thymus, tonsils, lymph nodes, and mucosa associated lymphatic tissue

11. Lymphatic System Components
Lymphatic organs
Discrete collections of lymphatic tissue; often encapsulated
Includes the thymus, spleen, tonsils, and lymph nodes

12. Lymphatic System Components
Bone Marrow
RBM
Works with thymus
Site of lymphocyte production
Hematopoietic progenitor cells

13. Figure 22.1

14. Lymphatic System Topics
Components of the lymphatic system
Functions of the lymphatic system
Organization of lymphatic vessels
Formation and flow of lymph
Lymphatic organs

15. Functions of the Lymphatic System
Drain interstitial fluid
Return leaked plasma proteins to blood
Transport dietary fats and lipid-soluble vitamins
Protect against pathogen invasion

16. Lymphatic System Topics
Components of the lymphatic system
Functions of the lymphatic system
Organization of lymphatic vessels
Formation and flow of lymph
Lymphatic organs

17. Organization of Lymphatic Vessels
Organized from smallest to largest:
Lymphatic capillaries
Lymphatic vessels
Afferent and efferent
Lymph nodes
Lymph trunks
Lymph ducts

18. Lymphatic Vessels Locations Structure Functions
Alongside small blood veins
Structure
Similar to small blood veins
Functions
Receive lymph from lymphatic capillaries
Convey lymph into and out of lymph nodes
Drain lymph into lymph trunks

19. Lymphatic Capillaries
Locations
Everywhere you find blood capillaries
Structure
Blind-ended
Greater permeability
Slightly larger diameter than blood capillaries
Have one-way valves + overlapping endothelial cells
Functions
Collect interstitial fluid; form lymph

20. Figure 22.2

21. Lacteals – Specialized Lymphatic Capillaries
Location
Small intestinal villi
Structure
Same as typical lymphatic capillaries
Functions
Collect interstitial fluid rich in digested fats
Drain lymph into lymphatic vessels
Chyle

22. Lymph Trunks Locations Structure Functions Alongside large blood veins
Similar to large blood veins
Functions
Receive lymph from lymphatic vessels
Drain lymph into lymph ducts

23. Lymph Trunks Lumbar Trunk Intestinal Trunk Bronchomediastinal Trunk
Subclavian Trunk
Jugular Trunk

24. Figure 22.3

25. Figure 22.3

26. Lymph Ducts Location Structure Function
Thoracic duct (left lymphatic duct)
Right lymphatic duct
Structure
Similar to large blood veins
Function
Receive lymph from lymph trunks
Drain lymph into subclavian veins

27. Lymphatic System Topics
Components of the lymphatic system
Functions of the lymphatic system
Organization of lymphatic vessels
Formation and flow of lymph
Lymphatic organs

28. Formation of Lymph
Lymph is formed when interstitial fluid drains into lymph capillaries

29. Brings back the 1 mmHg different between filtration / reabsorption
Fig 21.07

30. Figure 22.4

31. Lymphatic Capillaries
Arteries
Blood Capillaries
Interstitium
Lymphatic Capillaries
Lymphatic Vessels
Lymph Nodes
Lymph Trunks
Lymphatic Ducts
Subclavian Veins
Lymph Flow

32. Lymph Flow
Lymph flow aided by similar mechanisms as in the circulatory system:
Milking action of skeletal muscle contractions
Respiratory movements (pump)
Valves that prevent backflow of lymph
Vessel smooth muscle contraction

33. Lymph Drainage (Figure 22.1)

34. Lymphatic System Topics
Components of the lymphatic system
Functions of the lymphatic system
Organization of lymphatic vessels
Formation and flow of lymph
Lymphatic organs

35. Lymphatic Organ Classification
Primary Lymphatic Organs
Immunocompetency
Red bone marrow
Thymus
Secondary Lymphatic Organs
Lymph nodes
Spleen
Lymphatic nodules ***

36. Thymus Gland Location Structure Function Mediastinum
Bilobed; encapsulated; trabeculae (lobules)
Cortex and medulla
Contain T cells, dendritic and epithelial cells, macrophages
Function
Site of T cell maturation (positive selection)

37. Figure 22.5

38. Lymph Nodes Location Structure Functions Along lymphatic vessels
Encapsulated; oval; trabeculae (compartments)
Stroma and parenchyma (cortex + medulla)
Contain lymphocytes and other immune cells
Functions
Receive lymph from afferent lymphatic vessels
Filter foreign substances out of lymph
Drain lymph into efferent lymphatic vessels

39. Figure 22.6

41. Spleen Location Structure Functions
Left hypochondriac region between stomach’s fundus and diaphragm
Structure
Encapsulated (Stroma)
Parenchyma: White pulp and Red pulp
Functions
Next slide

42. Figure 22.7

43. Spleen Functions Receives blood from splenic artery
Phagocytoses pathogens
Mounts immune response against pathogens
Phagocytoses old blood cells
Stores blood platelets
Produces blood cells during fetal life

44. Lymphatic Nodules (Tissue)
Locations
GI tract, respiratory airways, urinary tract, and reproductive tract
MALT (Peyer’s patches, tonsils, appendix)
Structure
Unencapsulated; oval
Function
“Sentinels”
Mount immune response against foreign substances